text:
\section{Introduction}
The localization of energy for gravitating systems remains an
outstanding problem. Unlike all other source and interaction fields,
the standard techniques for identifying an energy-momentum density
for the gravitational field have only yielded various expressions
which are inherently reference frame dependent; these non-covariant
expressions are often referred to as pseudotensors. This
non-covariant feature can be understood as an inevitable consequence
of the equivalence principle, which precludes the detection of the
gravitational field at a point---so one cannot have a point-wise
well-defined energy-momentum density for gravitating systems (for a
good discussion of this point see Ch.~20 in \cite{MTW}).

The energy-momentum pseudotensor approach has largely been displaced
by the more modern perspective of quasi-local: energy-momentum is to
be associated with a closed 2-surface (for a review of the
quasi-local idea see \cite{Sza04}).
 One quasi-local formulation is in terms of the Hamiltonian.
 The Hamiltonian for evolving a (generally finite) spacetime region
includes a boundary term.
 Quasi-local quantities are associated with this Hamiltonian
boundary term.
 There are many possible quasi-local expressions simply because
there are many possible boundary terms.  They are all physically
meaningful, for each distinct boundary term is associated with a
distinct physical boundary condition (which is given by what must be
held fixed in the Hamiltonian variation).
 We note that this Hamiltonian quasi-local approach includes all the traditional
 pseudotensors, since
each is generated by a superpotential which serves as a special type
of Hamiltonian boundary term \cite{CN99,CNC99,CN00,beij,Nes04}. Via
the Hamiltonian formulation the ambiguities of the traditional
pseudotensors (which expression? which coordinate system?) are
clarified.  Hence, from the perspective of this Hamiltonian boundary
term approach to quasi-local energy-momentum the traditional
pseudotensors are still of interest.

For pseudotensor expressions the physical energy-momentum of the
gravitational field is inextricably bound up with the choice of
reference frame. This problem has long been recognized. Indeed soon
after Einstein had proposed his expression for gravitational energy
it was noted that with certain choices of coordinates it could give
both a nonzero energy for Minkowski space and a vanishing energy for
the Schwarzschild solution \cite{bauer,schr}. Notwithstanding this,
in many cases the reference frame ambiguity is not a
problem---simply because there is an obvious natural choice of
reference frame.

In particular in evaluating the energy-momentum for an
asymptotically flat gravitating system, the asymptotic Minkowski
space provides a natural and unambiguous reference for the
coordinate system. For this case almost all the classic
pseudotensors (except for M{\o}ller's 1958 expression \cite{Mol58})
give the standard value for the total energy-momentum. Now there is
another case where there is a natural and unambiguous reference:
namely in a small region, where one can use the flat tangent space
at some interior point to determine a Minkowski coordinate system.
Here we shall test the classical pseudotensors in this limit.

Specifically we will be concerned with the famous pseudotensors due
to Einstein \cite{Tra62}, Papapetrou \cite{Papa48,Gupta,Jackiw},
Landau-Lifshitz \cite{LL}, Bergmann-Thompson \cite{BT53},  Goldberg
\cite{Gol58},  M{\o}ller \cite{Mol58},  and Weinberg
\cite{Wein72,MTW}.
 Although in some interesting cases many of the pseudotensors
 give identical answers (see \cite{ACV96}), in the small vacuum region
limit considered here that will not be the case.

 Note that a good energy-momentum  expression for gravitating
systems should satisfy a variety of requirements (see, e.g.,
\cite{LY03,Sza04}), including giving the standard values for the
total quantities for asymptotically flat space and reducing to the
material energy momentum in the appropriate limit (equivalence
principle). No entirely satisfactory expression has yet been
identified.  One of the most restrictive requirements is positivity.

 It is generally accepted that gravitational energy should be
positive; indeed positive energy proofs have been heralded (e.g.,
\cite{SY79,Wit81,LY03}).  Positivity is difficult to prove in
general. One can regard positivity as an important test for
quasi-local energy expressions.
  One limit that is
not so difficult, and which has not been systematically investigated
for all the classical pseudotensor expressions, is the small region
limit. The small region requirements have not yet been applied to
many energy-momentum expressions. We found that they afford both
interesting restrictions and unexpected freedom.

For a small region within matter the equivalence principle requires
that the energy-momentum expression should be dominated by the
material energy-momentum tensor.  On the other hand the positivity
of gravitational energy in a small vacuum region is assured if its
Taylor series expansion in Riemann normal coordinates is at the
second order a positive multiple of the Bel-Robinson tensor.

Some time ago Deser, Franklin and Seminara \cite{DFS99} presented a
discussion of pseudotensors in a small region, which has been a
major sources of inspiration for us. In that work the main
techniques that we will use here were developed. They examined the
Taylor expansion of a pseudotensor around a preselected (vacuum)
point using Riemann normal coordinates (RNC). Considering
pseudotensors derived from superpotentials, it was  noted that the
leading order non-vanishing vacuum expansion was at second order and
would be quadratic in the Riemann tensor. They then identified four
basis expressions for such terms and related them to the famous
Bel-Robinson tensor.

They argued that it is desired that one get the Bel-Robinson tensor,
$B_{\alpha\beta\mu\nu}$. They found exactly one such expression from
a certain linear combination, $B_{\alpha\beta\mu\nu}
=\partial^2{}_{\mu\nu}(L_{\alpha\beta}+\frac{1}{2}E_{\alpha\beta})$,
of the Landau-Lifshitz and Einstein pseudotensors, a combination
which they argued was unique.

We have reexamined the issue, considering all the aforementioned
pseudotensors.   Here we report in detail on our results, which were
first obtained in \cite{So06} and briefly announced in
\cite{icga7so}. We found that  no classical holonomic pseudotensor
gives the required second order vacuum result (surely this
contributed to the difficulty in finding a positive gravitational
energy proof). However, using similar methods to the work just
mentioned, we found another independent combination of the
Bergmann-Thompson, Papapetrou and Weinberg pseudotensors, and thus a
one parameter set of pseudotensors, with the same desired
Bel-Robinson property. (This was overlooked in the earlier work
because they had not allowed for pseudotensors which require the
explicit use of the Minkowski metric as a reference).

\section{The classical pseudotensors}

The classical pseudotensors can be obtained by suitably rearranging
Einstein's equation:
\begin{equation}
G_{\mu\nu}=\kappa T_{\mu\nu},\label{einfeq}\end{equation}
(where $\kappa:=8\pi G/c^4$). One specific way is to choose a
suitable {\em superpotential} $U^{\mu\lambda}{}_\nu\equiv
U^{[\mu\lambda]}{}_\nu$ and {\em define} the associated
gravitational energy-momentum density pseudotensor by
\begin{equation}
2\kappa t^\mu{}_\nu:=\partial_\lambda
U^{\mu\lambda}{}_\nu-2|g|^{\frac12}G^\mu{}_\nu. \label{paradigm}
\end{equation}
Einstein's equation now takes the form
\begin{equation}
2\kappa {\cal T}^\mu{}_\nu:=2\kappa(|g|^{\frac12}T^\mu{}_\nu
+t^\mu{}_\nu)=\partial_\lambda U^{\lambda\mu}{}_\nu.
\end{equation}
Because of the antisymmetry of the superpotential the total
energy-momentum density complex is automatically conserved:
$\partial_\mu {\cal T}^\mu{}_\nu\equiv0$.

 There are some variations on the idea, the classical pseudotensorial total energy-momentum density
complexes all follow from associated superpotentials according to
one of the patterns
\begin{equation}
2\kappa {\cal T}^\mu{}_\nu=\partial_\lambda
U^{\mu\lambda}{}_\nu,\quad
2\kappa {\cal T}^{\mu\nu}=\partial_\lambda U^{\mu\lambda\nu},%
\quad 2\kappa {\cal
T}^{\mu\nu}=\partial_{\alpha\beta}H^{\alpha\mu\beta\nu},
\end{equation}
where the superpotentials have certain symmetries which
automatically guarantee conservation: specifically
$U^{\mu\lambda}{}_\nu\equiv U^{[\mu\lambda]}{}_\nu$,
 $U^{\mu\lambda\nu}\equiv
U^{[\mu\lambda]\nu}$, while $H^{\alpha\mu\beta\nu}$ has the
symmetries of the Riemann tensor. In particular the Einstein total
energy-momentum density follows from the Freud superpotential
\cite{Freud}
\begin{equation}
U_{\rm F}^{\mu\lambda}{}_\nu:=-|g|^{\frac12}g^{\beta\sigma}
\Gamma^\alpha{}_{\beta\gamma}\delta^{\mu\lambda\gamma}_{\alpha\sigma\nu};\label{UF}
\end{equation}
 while the Bergmann-Thompson \cite{BT53}, Landau-Lifshitz \cite{LL}, Papapetrou \cite{Papa48}, Weinberg \cite{Wein72} and
 M{\o}ller \cite{Mol58}
 expressions can be obtained from the respective superpotentials
\begin{eqnarray}
U_{\rm BT}^{\mu\lambda\nu}&:=&g^{\nu\delta}U_{\rm
F}^{\mu\lambda}{}_\delta,\label{UBT}\\
U_{\rm LL}^{\mu\lambda\nu}&:=&|g|^{\frac12}U_{\rm
BT}^{\mu\lambda\nu},\quad {\mathrm{equivalently}} \quad H_{\rm
LL}^{\alpha\mu\beta\nu}:=|g|\delta^{\mu\alpha}_{ma}
g{}^{a\beta}g^{m\nu},\label{ULL}\label{HLL}\\
H_{\rm
P}^{\alpha\mu\beta\nu}&:=&\delta^{\mu\alpha}_{ma}\delta^{\nu\beta}_{nb}\bar
g{}^{ab}(|g|^{\frac12}g^{mn}),\label{HP}\\
H_{\rm
W}^{\alpha\mu\beta\nu}&:=&\delta^{\mu\alpha}_{ma}\delta^{\nu\beta}_{nb}|\bar
g|^{\frac12}\bar g{}^{ab}(-{\bar g}^{mc}{\bar g}^{nd}+{\frac12}{\bar
g}^{mn}{\bar g}^{cd}) g_{cd},\label{HW}\\
U_{\rm
M}^{\mu\lambda}{}_\nu&:=&-|g|^{\frac12}g^{\beta\sigma}\Gamma^\alpha{}_{\beta\nu}\delta^{\mu\lambda}_{\alpha\sigma}
\equiv |g|^{\frac12}g^{\beta\mu}g^{\lambda\delta}(\partial_\beta
g_{\delta\nu}-\partial_\delta g_{\beta\nu}) \label{UM}.
\end{eqnarray}
(Note that all indicies in this work refer to spacetime and range
from 0 to 3, otherwise  our conventions follow \cite{MTW}.)

These expressions are all non-covariant.  As they depend on the
coordinates in a non-tensorial way, they can at best be expected to
give sensible energy-momentum values only in certain
coordinates---which are in some suitable sense nearly Minkowski
coordinates. Given that we have such coordinates we also have an
underlying Minkowski space reference structure.  Some of the
superpotentials explicitly include this reference metric, which here
 has the Minkowski values $\bar g_{ij}={\rm diag}(-1,+1,+1,+1)$.
Our basic philosophy is that energy-momentum is properly a covector,
and hence properly the energy-momentum density should be a weight
one density with the index positions $t^\mu{}_\nu$.  For all of the
classical pseudotensors  this can be achieved by introducing
suitable factors of the Minkowski metric and its determinant.
According to this philosophy only the Einstein and M{\o}ller
expressions have proper expressions that do not explicitly need the
Minkowski metric associated with the chosen coordinates.

It should be noted that, while in general identifying physically
meaningful Minkowski coordinates is problematical, in the small
region case of interest to us here at any chosen point there is a
natural local Minkowski structure, as we discuss in the next
section.

\section{Some Technical background}

\subsection{Riemann normal coordinates (RNC)}

As Riemann first argued (see, e.g., Spivak \cite{Spivak}), at any
preselected point one can choose coordinates such that at the point
$x^\mu=0$, the metric coefficients have the standard flat values,
the first derivatives of the metric vanish, and the second
derivatives have the minimum number (20 for $n=4$) of independent
values. Specifically
\begin{equation}\fl\qquad
g_{\alpha\beta}|_0=\bar g_{\alpha\beta}, \quad \partial_\mu
g_{\alpha\beta}|_0=0, \quad
3\partial_{\mu\nu}g_{\alpha\beta}|_0=-(R_{\alpha\mu\beta\nu}+R_{\alpha\nu\beta\mu})|_0,
\end{equation}
where $R^\alpha{}_{\beta\mu\nu}$ is the Riemannian curvature tensor%
, and, in our case, $\bar
g_{\alpha\beta}=\eta_{\alpha\beta}=\hbox{diag}(-1,+1,+1,+1)$ is the
Minkowski spacetime metric.  The corresponding Levi-Civita
connection values are
\begin{equation}
\Gamma^\alpha{}_{\beta\gamma}|_0=0,\qquad 3\partial_\mu
\Gamma^\alpha{}_{\beta\nu}|_0=-(R^\alpha{}_{\beta\nu\mu}+R^\alpha{}_{\nu\beta\mu})|_0.
\end{equation}

\subsection{Quadratic curvature basis}
It turns out that when expanded in RNC the lowest non-vanishing
vacuum energy-momentum expressions are of the second order and are
quadratic in the curvature tensor:
$t_{\mu\nu}\sim(R_{\cdot\cdot\cdot\cdot}R^\cdot{}_\cdot{}^\cdot{}_\cdot)_{\mu\nu
ij}x^ix^j$. An investigation \cite{DFS99} of all such possible terms
(taking into account the Weyl = vacuum Riemann tensor symmetries)
shows that they can be written in terms of
\begin{equation}
Q_{\mu\alpha\nu\beta}:=R_{a\mu b\alpha}R^a{}_\nu{}^b{}_\beta\equiv
Q_{\nu\beta\mu\alpha}\equiv Q_{\alpha\mu\beta\nu},
\end{equation}
where all the symmetries have been indicated. The cited work defined
the three basis combinations
\begin{equation}\fl\qquad
X_{\mu\nu\alpha\beta}:=2Q_{\alpha(\mu\nu)\beta}, \quad
Y_{\mu\nu\alpha\beta}:=2Q_{\alpha\beta(\mu\nu)}, \quad
Z_{\mu\nu\alpha\beta}:=Q_{\alpha\mu\beta\nu} +
Q_{\alpha\nu\beta\mu},
\end{equation}
along with the trace tensor
\begin{equation}
T_{\mu\nu\alpha\beta}=-\frac16
g_{\mu\nu}Q^\sigma{}_{\alpha\beta\sigma}.
\end{equation}
One could write all our vacuum expansions to second order as linear
combinations of $X$, $Y$, $Z$, $T$.  However it is more suitable for
physical purposes to use the Bel-Robinson tensor.

\subsection{The Bel-Robinson and two other tensors}
The Bel-Robinson tensor
\begin{equation}
B_{\mu\nu\alpha\beta}=R_{\rho\mu\sigma\alpha}R^\rho{}_\nu{}^\sigma{}_\beta+R_{\rho\mu\sigma\alpha}R^\rho{}_\nu{}^\sigma{}_\beta
-\frac12g_{\mu\nu}R_{\alpha\rho\sigma\tau}R_\beta{}^{\rho\sigma\tau}
\end{equation}
has many well known remarkable properties, see e.g.,
\cite{DFS99,Gar01}.  For our considerations we are interested in it
only in the vacuum, where the Riemann tensor reduces to the Weyl
tensor. In this case the Bel-Robinson tensor is completely symmetric
and traceless, and the last term admits an alternate form using
\begin{equation}4R_{\alpha\rho\sigma\tau}R_\beta{}^{\rho\sigma\tau}
=g_{\alpha\beta}R_{\kappa\lambda\gamma\delta}R^{\kappa\lambda\gamma\delta}.\label{traceid}\end{equation}
In vacuum the Bel-Robinson tensor $B$ and two other convenient
tensors $S$ and $K$
 are given by
\begin{eqnarray}
B_{\alpha\beta\mu\nu}
&:=&R_{\alpha\lambda\mu\sigma}R_{\beta}{}^\lambda{}_{\nu}{}^{\sigma}
+R_{\alpha\lambda\nu\sigma}R_{\beta}{}^{\lambda}{}_{\mu}{}^{\sigma}
-\frac{1}{8}g_{\alpha\beta}g_{\mu\nu}R_{\kappa\lambda\gamma\delta}R^{\kappa\lambda\gamma\delta},  \\
S_{\alpha\beta\mu\nu}
&:=&R_{\alpha\mu\lambda\sigma}R_{\beta\nu}{}{}^{\lambda\sigma}
+R_{\alpha\nu\lambda\sigma}R_{\beta\mu}{}{}^{\lambda\sigma} +\frac14
g_{\alpha\beta}g_{\mu\nu}R_{\kappa\lambda\gamma\delta}R^{\kappa\lambda\gamma\delta},\\
K_{\alpha\beta\mu\nu}&:=&R_{\alpha\lambda\beta\sigma}R_\mu{}^\lambda{}_\nu{}^\sigma+R_{\alpha\lambda\beta\sigma}R_\nu{}^\lambda{}_\mu{}^\sigma
-\frac38g_{\alpha\beta}g_{\mu\nu}R_{\kappa\lambda\gamma\delta}R^{\kappa\lambda\gamma\delta}.
\end{eqnarray}
In term of the aforementioned basis for quadratic terms
\begin{equation}
B=Z+3T, \qquad S=-2X+2Z-6T, \qquad K=Y+9T.
\end{equation}
(Here and below we have suppressed some obvious indicies.)

Our leading order non-vanishing vacuum expressions will be given as
linear combinations of $B$, $S$, and $K$. As can be directly
verified, these three combinations (by virtue of (\ref{traceid}))
satisfy the divergence free condition,
\begin{equation}
\partial_\beta (x^i x^j t_{ij}{}^{\alpha\beta})\equiv2 x^j t_{ij}{}^{\alpha i}\equiv0,
\end{equation}
and all such tensors are some linear combination of these three.
While the tensor $S$ has been known for a long time, we here draw
attention to the tensor $K$ which also enjoys this divergence free
property.

\section{The small region limit}

Here the small region values for the classical pseudotensors are
presented.

\subsection{Einstein}

The Einstein total energy-momentum complex can be obtained from the
Freud superpotential (\ref{UF}):
\begin{eqnarray}\fl\qquad\quad
2\kappa {\cal T}_{\rm E}^\mu{}_\nu&:=&\partial_\lambda U_{\rm
F}^{\mu\lambda}{}_\nu:=\partial_\lambda(-|g|^{\frac12}g^{\beta\sigma}
\Gamma^\alpha{}_{\beta\gamma}\delta^{\mu\lambda\gamma}_{\alpha\sigma\nu})\qquad
\\
\fl&\equiv&-|g|^{\frac12}g^{\beta\sigma}
({\frac12}R^\alpha{}_{\beta\lambda\gamma}-\Gamma^\alpha{}_{\delta\lambda}\Gamma^\delta{}_{\beta\gamma})\delta^{\mu\lambda\gamma}_{\alpha\sigma\nu}
-
\partial_\lambda(|g|^{\frac12}g^{\beta\sigma})
\Gamma^\alpha{}_{\beta\gamma}\delta^{\mu\lambda\gamma}_{\alpha\sigma\nu}\qquad\\
&\equiv&2|g|^{\frac12} G^\mu{}_\nu-
|g|^{\frac12}[\Gamma^\delta{}_{\delta\lambda}\Gamma^{\alpha\sigma}{}_\gamma-\Gamma^{\sigma\beta}{}_\lambda\Gamma^\alpha{}_{\beta\gamma}
]\delta^{\mu\lambda\gamma}_{\alpha\sigma\nu}.\qquad
\end{eqnarray}
Using the Einstein field equation (\ref{einfeq}) this relation takes
the form
\begin{equation}
{\cal T}_{\rm E}^\mu{}_\nu=|g|^{\frac12}T^\mu{}_\nu+t_{\rm
E}^\mu{}_\nu,\label{eincmplx}
\end{equation}
where the Einstein energy-momentum pseudotensor density is
\begin{equation}t_{\rm E}^\mu{}_\nu:=-(2\kappa)^{-1}
|g|^{\frac12}[\Gamma^\delta{}_{\delta\lambda}\Gamma^{\alpha\sigma}{}_\gamma-\Gamma^{\sigma\beta}{}_\lambda\Gamma^\alpha{}_{\beta\gamma}
]\delta^{\mu\lambda\gamma}_{\alpha\sigma\nu}.
\end{equation}
 Expanding in
normal coordinates, to zeroth order the pseudotensor vanishes, so
(\ref{eincmplx}) reduces to ${\cal T}_{\rm E}^\mu{}_\nu=
|g|^{\frac12}T^\mu{}_\nu$, which is the matter interior limit
expected from the equivalence principle. In vacuum ${\cal T}_{\rm
E}=t_{\rm E}$, and the first non-vanishing contribution appears in
the second order (note: all trace $\Gamma$ terms are proportional to
Ricci and hence vanish in vacuum); after some computation we find in
vacuum
\begin{equation}\fl\quad\quad
2\kappa {\cal T}_{\rm E}^\mu{}_\nu=2\kappa t_{\rm E}^\mu{}_\nu
=|g|^{\frac12}(-2\Gamma^{\mu\beta}{}_\alpha\Gamma^\alpha{}_{\beta\nu}+\delta^\mu_\nu\Gamma^{\sigma\beta}{}_\alpha\Gamma^\alpha{}_{\beta\sigma}
) \simeq{\frac{x^ix^j}{2\cdot3\cdot3}}(4B-S)_{ij}{}^\mu{}_\nu,\quad
\end{equation}
a result known for some time \cite{MTW,Gar73,DFS99,Gar01}.

\subsection{Bergmann-Thompson, Landau-Lifshitz and Goldberg}

The total energy-momentum complex proposed by Bergmann and Thompson
\cite{BT53} can be obtained from a transvected version of the Freud
superpotential (\ref{UBT}):
\begin{equation}
2\kappa {\cal T}_{\rm BT}^{\mu\nu}:=\partial_\lambda(
g^{\nu\delta}U_{\rm F}^{\mu\lambda}{}_\delta) \equiv 2\kappa {\cal
T}_{\rm E}^\mu{}_\delta g^{\nu\delta} -|g|^{\frac12}g^{\beta\sigma}
\Gamma^\alpha{}_{\beta\gamma}\delta^{\mu\lambda\gamma}_{\alpha\sigma\delta}\partial_\lambda
g^{\nu\delta}.\label{BTcmplx}
\end{equation}
Consequently the Bergmann-Thompson gravitational energy-momentum
pseudotensor density, found from a decomposition of the form ${\cal
T}_{\rm BT}=|g|^{\frac12}T+t_{\rm BT}$, is
\begin{equation}
t_{\rm BT}^{\mu\nu}=t_{\rm E}^\mu{}_\delta g^{\nu\delta}
-|g|^{\frac12}g^{\beta\sigma}
\Gamma^\alpha{}_{\beta\gamma}\delta^{\mu\lambda\gamma}_{\alpha\sigma\delta}\partial_\lambda
g^{\nu\delta}.
\end{equation}
In normal coordinates to zeroth order the pseudotensor $t_{\rm BT}$
vanishes so ${\cal T}_{\rm BT}=|g|^{\frac12}T$, which is the desired
limit inside of matter. In vacuum the complex (\ref{BTcmplx})
reduces to the pseudotensor, which has its first nonvanishing
contribution at the second order:
\begin{equation}\fl\quad
2\kappa t_{\rm
BT}^{\mu\nu}=|g|^{\frac12}\left[2\Gamma^{\mu}{}_{\lambda\sigma}
\Gamma^{[\nu\lambda]\sigma} -2\Gamma_{\lambda\sigma}{}^{\mu}
\Gamma^{(\nu\sigma)\lambda}
+g^{\mu\nu}\Gamma_{\lambda\sigma\tau}\Gamma^{\sigma\lambda\tau}\right]
\simeq
{\frac{x^ix^j}{2\cdot3\cdot3}}(7B+{\frac12}S)_{ij}{}^{\mu\nu}.\
\label{BTvac}
\end{equation}

The better known Landau-Lifshitz expression \cite{LL} can be
obtained from this transvected superpotential with an additional
improper density weight factor (\ref{ULL}):
\begin{equation}\fl\qquad
2\kappa {\cal T}_{\rm LL}^{\mu\nu}:=\partial_\lambda({|g|}^{\frac12}
g^{\nu\delta}U_{\rm F}^{\mu\lambda}{}_\delta) \equiv 2\kappa
|g|^{\frac12}{\cal T}_{\rm E}^{\mu\nu}-|g|^{\frac12}g^{\beta\sigma}
\Gamma^\alpha{}_{\beta\gamma}\delta^{\mu\lambda\gamma}_{\alpha\sigma\delta}\partial_\lambda
(|g|^{\frac12}g^{\nu\delta}).
\end{equation}
A short calculation shows that this extra weight factor makes no
contribution to the zeroth-order matter-interior limit nor to the
second order result in vacuum. Thus the Landau-Lifshitz vacuum
result is  given by (\ref{BTvac}), as was noted some time ago
\cite{DFS99}.

By the way, Goldberg \cite{Gol58} has proposed an infinite class of
arbitrary density weight energy-momentum expressions obtained from
those of Einstein and Landau-Lifshitz in a manner similar to that
just considered. For essentially the same reasons, Goldberg's
weighted density factors will not yield any modified values in the
small region limits we are considering here.

\subsection{Papapetrou}

For our analysis of the Papapetrou \cite{Papa48} and Weinberg
\cite{Wein72} expressions we use the Einstein tensor expansion
\begin{eqnarray}\fl\quad
2G^{\mu\nu}&\equiv&\delta^{\mu\alpha}_{ma}\delta^{\nu\beta}_{nb}g^{ab}
\left[{\textstyle\frac12}g^{ef}g^{mn}-g^{me}g^{nf}\right]\partial_{\alpha\beta}g_{ef}\quad\quad\quad\nonumber\\
\fl\quad&+&
(2g^{\beta\mu}g^{\gamma\nu}-g^{\mu\nu}g^{\beta\gamma})\left(\partial_\alpha
g^{\alpha\delta}\Gamma_{\delta\beta\gamma}-\partial_\gamma
g^{\alpha\delta}\Gamma_{\delta\beta\alpha}+\Gamma^\alpha{}_{\delta\alpha}\Gamma^\delta{}_{\beta\gamma}
-\Gamma^\alpha{}_{\delta\gamma}\Gamma^\delta{}_{\beta\alpha}\right).\quad\quad
\label{Einsteintensor}
\end{eqnarray}
For the Papapetrou energy-momentum complex
\cite{Papa48,Gupta,Jackiw} we find, using (\ref{Einsteintensor}) and
the appropriate superpotential (\ref{HP}),
\begin{eqnarray}\fl\quad
2\kappa {\cal T}^{\mu\nu}_{\rm
P}&:=&\delta^{\mu\alpha}_{ma}\delta^{\nu\beta}_{nb}\bar
g{}^{ab}\partial_{\alpha\beta}(|g|^{\frac12}g^{mn})\\
\fl\quad&\equiv&\delta^{\mu\alpha}_{ma}\delta^{\nu\beta}_{nb}
(g{}^{ab}-\Delta g^{ab})\partial_\alpha
\Bigl[|g|^{\frac12}({\frac12}g^{ef}g^{mn}-g^{me}g^{nf})\partial_\beta g_{ef}\Bigr]\\
\fl\quad&\simeq&2|g|^{\frac12}G^{\mu\nu}+|g|^{\frac12}
(2g^{\beta\mu}g^{\gamma\nu}-g^{\mu\nu}g^{\beta\gamma})\left[\partial_\gamma
g^{\alpha\delta}\Gamma_{\delta\beta\alpha}
+\Gamma^\alpha{}_{\delta\gamma}\Gamma^\delta{}_{\beta\alpha}\right]\nonumber\\
\fl\quad&&+\delta^{\mu\alpha}_{ma}\delta^{\nu\beta}_{nb} \Delta
g^{ab}|g|^{\frac12}g^{me}g^{nf}
\partial_{\alpha\beta}
g_{ef}\nonumber\\
\fl\quad&&+\delta^{\mu\alpha}_{ma}\delta^{\nu\beta}_{nb}
g{}^{ab}|g|^{\frac12}\Bigl(-{\frac12}g^{ei}g^{fj}g^{mn}
+g^{mi}g^{ej}g^{nf}+g^{me}g^{ni}g^{fj}\Bigr)\partial_\alpha
g_{ij}\partial_\beta g_{ef},\quad\quad\label{papaexp}
\end{eqnarray}
where we use for any  metric expression $\Delta F:=F-\bar F$. Here
we have indicated one way to arrange things so that we can get the
terms of the desired orders. In normal coordinates to zeroth order
within matter the expansion (\ref{papaexp}) clearly reduces to the
desired result. In vacuum to second order a lengthy calculation
yields
\begin{equation}
2\kappa t^{\mu\nu}_{\rm P}\simeq
{\frac{x^ix^j}{3\cdot3}}[4B-S-K]_{ij}{}^{\mu\nu}.
\end{equation}

\subsection{Weinberg}
With the help of (\ref{Einsteintensor}) and the appropriate superpotential (\ref{HW}) for the Weinberg \cite{Wein72}
expression (note: the same expression is considered in \cite{MTW} \S
20.2) we find
\begin{eqnarray}\fl\quad
&&2\kappa {\cal T}^{\mu\nu}_{\rm W}
:=\delta^{\mu\alpha}_{ma}\delta^{\nu\beta}_{nb}|\bar
g|^{\frac12}\bar g{}^{ab}(-{\bar g}^{me}{\bar g}^{nf}+{\frac12}{\bar
g}^{mn}{\bar g}^{ef})
\partial_{\alpha\beta}g_{ef}\\
\fl\quad&&\quad\equiv\delta^{\mu\alpha}_{ma}\delta^{\nu\beta}_{nb}|g|^{\frac12}
g{}^{ab}( -g^{me} g^{nf}+{\frac12} g^{mn} g^{ef})\partial_{\alpha\beta}g_{ef}\nonumber\\
\fl\quad&&\quad-\delta^{\mu\alpha}_{ma}\delta^{\nu\beta}_{nb}\Delta\left[|g|^{\frac12}
g^{ab}(-g^{me} g^{nf}+{\frac12} g^{mn} g^{ef})\right]\partial_{\alpha\beta}g_{ef}\\
\fl\quad&&\quad\simeq 2|g|^{\frac12}G^{\mu\nu}+|g|^{\frac12}
(2g^{\beta\mu}g^{\gamma\nu}-g^{\mu\nu}g^{\beta\gamma})\left[\partial_\gamma
g^{\alpha\delta}\Gamma_{\delta\beta\alpha}
+\Gamma^\alpha{}_{\delta\gamma}\Gamma^\delta{}_{\beta\alpha}\right]\\
\fl\quad
&&-\delta^{\mu\alpha}_{ma}\delta^{\nu\beta}_{nb}|g|^{\frac12}
\Bigl[g^{ai}g^{bj}
 g^{me} g^{nf}+g^{ab} (g^{mi}g^{ej} g^{nf}+g^{me}  g^{ni}g^{fj}
-{\frac12} g^{mn} g^{ei}g^{fj})\Bigr]\Delta
g_{ij}\partial_{\alpha\beta}g_{ef}.\nonumber
\end{eqnarray}
Here we have indicated one way to get the desired orders. In normal
coordinates, as expected, to zeroth order it gives the desired
material limit; in vacuum to second order after a long calculation
we found
\begin{equation}
2\kappa t^{\mu\nu}_{\rm W}\simeq {\frac{x^ix^j}
{3\cdot3}}[-B-2S-3K]_{ij}{}^{\mu\nu}.
\end{equation}

\subsection{M{\o}ller}

M{\o}ller's holonomic energy-momentum complex \cite{Mol58} follows
from the superpotential (\ref{UM}).  We find
\begin{eqnarray}\fl\quad
2\kappa {\cal T}_{\rm M}^\mu{}_\nu
&:=&-\partial_\lambda(|g|^{\frac12}g^{\beta\sigma}\Gamma^\alpha{}_{\beta\nu})\delta^{\mu\lambda}_{\alpha\sigma}
\equiv\partial_\lambda\left[|g|^{\frac12}g^{\beta\mu}g^{\lambda\delta}(\partial_\beta
g_{\delta\nu}-\partial_\delta g_{\beta\nu})\right]\\
\fl\quad&\equiv&|g|^{\frac12}g^{\beta\mu}g^{\lambda\delta}(\partial_{\lambda\beta}
g_{\delta\nu}-\partial_{\lambda\delta} g_{\beta\nu})
+\partial_\lambda\left[|g|^{\frac12}g^{\beta\mu}g^{\lambda\delta}\right](\partial_\beta
g_{\delta\nu}-\partial_\delta g_{\beta\nu})\\
\fl\quad&\simeq&|g|^{\frac12}R^\mu{}_\nu-\frac12g^{\mu\beta}g^{\delta\lambda}
\left(\partial_{\lambda\delta}g_{\beta\nu}-\partial_{\lambda\beta}g_{\delta\nu}+\partial_{\delta\nu}g_{\lambda\beta}
-\partial_{\beta\nu}g_{\lambda\delta}\right)+O(\Gamma^2) \\
\fl\quad &\simeq&|g|^{\frac12}R^\mu{}_\nu+O(x^2).
\end{eqnarray}
Note that the M{\o}ller energy-momentum complex fails to give the
correct small region material limit (by the way, it also fails to
agree with the proper asymptotic limit presented in \cite{MTW}, \S
20.2). Using Einstein's equation and (\ref{paradigm}) we have to
zeroth order
\begin{equation}
2t_{\rm M}^\mu{}_\nu=-(T^\mu{}_\nu+\frac12 \delta^\mu_\nu
T^\delta{}_\delta),
\end{equation}
which is non-vanishing inside of matter. Therefore the M{\o}ller
expression does not satisfy the {\it equivalence principle}. From
our perspective M{\o}ller's holonomic expression is thus {\em
disqualified} as a satisfactory description of energy-momentum.

Although it is consequently only of academic interest, nevertheless,
for completeness, we briefly report here on the small region vacuum
limit of M{\o}ller's pseudotensor. From a long calculation, which
requires the 4th order Riemann normal coordinate expansion for the
metric \cite{Ni},
\begin{equation}
g_{\alpha\beta,\sigma\lambda\mu\nu}={\rm
P}(-\frac{1}{20}R_{\alpha\sigma\beta\lambda;\mu\nu}
+\frac{2}{45}R^{\xi}{}_{\sigma\beta\lambda}R_{\xi\mu\alpha\nu}),
\end{equation}
where $\rm P$ is the $\sigma\lambda\mu\nu$ symmetrization projection
operator, we found to second order
\begin{equation}
2\kappa t_{\rm M}^\mu{}_\nu\simeq
\frac{x^ix^j}{3\cdot3}[2B-\frac{1}{2}S-K]_{ij}{}^\mu{}_\nu.
\end{equation}

\section{Combinations of the classical pseudotensors}
The M{\o}ller expression is ruled out of our further considerations
by its material and asymptotic limit. The other four expressions are
satisfactory asymptotically and in the material limit.  However none
of them give a good small vacuum value. Following the example of
\cite{DFS99} we shall consider linear combinations of the four
satisfactory classical pseudotensors.  In the aforementioned work it
was noted that in vacuum a certain combination of the Einstein and
the Landau-Lifshitz (or equivalently the Bergmann-Thompson)
expressions is to second order proportional to the Bel-Robinson
tensor; specifically they found
\begin{equation}
B_{\alpha\beta\mu\nu}=\partial^2_{\mu\nu}(t_{\rm
E}+\textstyle{\frac12}t_{\rm LL})_{\alpha\beta}.
\end{equation}

This raises a couple of issues not addressed in that earlier work.
In particular one should pay attention to the overall normalization
in order to satisfy the small region matter interior limit (the same
normalization will also give the correct magnitude for the total
energy momentum of an asymptotically flat space).  One also must
cope with the mixed index positions which naturally occur for the
Einstein pseudotensor in contrast with the two contravariant indices
of the other three pseudotensors. Algebraically at the RNC origin it
matters not whether one raises the index on the Einstein expression
with $g^{\alpha\beta}$ or ${\bar g}{}^{\alpha\beta}$. However only
the latter choice is allowed if we wish to preserve the conservation
property.  Thus we see another reason why we are paralyzed unless we
allow for the explicit appearance of the Minkowski metric in RNC.
Hence we {\it define}
\begin{equation}
t^{\mu\nu}_{\rm E}:={\bar g}{}^{\nu\gamma}t^\mu_{\rm E}{}_\gamma.
\end{equation}

With this convention we can consider the linear combinations
(suppressing indicies for simplicity)
\begin{eqnarray}\fl\quad
2\kappa t&:=&2\kappa[et_{\rm E}+bt_{\rm BT}+pt_{\rm P}+wt_{\rm
W}]\simeq(e+b+p+w)2G\\
\fl\quad&&\!\!\!
+{\frac19}xx\left[B(2e+{\frac72}b+4p-w)-S({\frac12}e-{\frac14}b+p+2w)-K(p+3w)\right],\nonumber
\end{eqnarray}
where we use $\simeq$ to mean that only the zeroth order and second
order vacuum values have been indicated. In order to have the
correct asymptotic and material limits one must require $e+b+p+w=1$,
and for a good small vacuum limit to Bel-Robinson the coefficients
of $S$ and $K$ should vanish---thus three restrictions on the four
parameters. A convenient way to parameterize the set of acceptable
coefficients is
\begin{equation}
e=1-\lambda, \quad b=2/3,\quad p=3\lambda/2-1, \quad
w=-\lambda/2+1/3,
\end{equation}
which yields
\begin{eqnarray}
 t(\lambda)&=&(1-\lambda)t_{\rm E}+\frac23t_{\rm BT}+\left(\frac{\lambda}{2}-\frac13\right)(3t_{\rm
P}-t_{\rm W})\\
&=&\left[t_{\rm E}+\frac23t_{\rm BT}-\frac13(3t_{\rm P}-t_{\rm
W})\right] +\lambda\left[ -t_{\rm E}+\frac12(3t_{\rm
P}-t_{\rm W})\right]\label{2terms}\\
&\simeq&(2\kappa)^{-1}\left[2G+\lambda Bxx/2\right]=T+\lambda
Bxx/4\kappa.
\end{eqnarray}
The combination in the first bracket of (\ref{2terms}) gives both
the desired asymptotic and small region material result, but
vanishes to 2nd order in the small vacuum region limit; the
combination in the second bracket vanishes both asymptotically and
in the material limit, while in the small vacuum limit it gives the
desired 2nd order Bel-Robinson contribution. {\it Formally} we can
choose any value for $\lambda$. Physically we want $\lambda>0$. We
know of no principle to fix the magnitude of $\lambda$.  Some values
stand out: $\lambda=2/3$ gives the (here properly normalized) case
found earlier \cite{DFS99}:
\begin{equation}
t(2/3)=(1/3)t_{\rm E}+(2/3) t_{\rm BT}\simeq T+Bxx/6\kappa.
\end{equation}
The choice $\lambda=1$ gives another simple case:
\begin{equation}
t(1)=(2/3)t_{\rm BT}+(1/6)(3t_{\rm P}-t_{\rm W})\simeq
T+Bxx/4\kappa.
\end{equation}

Note that the earlier work found just one expression.  The
restricted form of the expressions considered there (i.e., not
explicitly containing $\bar g$) are not in our opinion justified. To
take linear combinations we need to get the indicies on the Einstein
pseudotensor at the same level, that requires $\bar g_{\mu\nu}$.
Moreover, the Landau-Lifshitz expression is actually of the wrong
density weight (this can be adjusted by including a suitable power
of $|\bar g|$). To the order considered in that work one can equally
well use the Bergmann-Thompson expression, which we have used here.

Comparing with the earlier work, we note that both the Weinberg and
Papapetrou expressions cannot be constructed without explicitly
using a reference.  We certainly want to allow for these
expressions---especially the latter which has been generalized to
define the total energy for an asymptotically anti-de Sitter space
\cite{AD82}.

\section{Conclusion}

In this work we found the values for the gravitational
energy-momentum density given by the famous classical pseudotensors:
Einstein, Papapetrou, Landau-Lifshitz, Bergmann-Thompson, Goldberg,
M{\o}ller, and Weinberg, in the small region limit to lowest
non-vanishing order in normal coordinates. All except M{\o}ller's
were found to have the zeroth order material limit required by the
equivalence principle. For small vacuum regions we found that {\it
none} of these classical holonomic pseudotensors satisfies the 2nd
order vacuum criterion of being proportional to the Bel-Robinson
tensor.

However certain linear combinations of these classical holonomic
pseudotensors do give the desired 2nd order vacuum result.
Generalizing an earlier work \cite{DFS99} which had identified one
case, we found another independent linear combination satisfying
this requirement---and hence a one parameter set of linear
combinations of the Einstein, Bergmann-Thompson, Papapetrou and
Weinberg pseudotensors with this same desired property.  (This had
been overlooked because the earlier work had not allowed for the
explicit use of the Minkowski metric as a reference in the
pseudotensor.)

Regarding the physical meaning of these combinations, although that
has not been worked out in detail, there is a straightforward way to
find it. Each viable parameter choice fixes a specific Hamiltonian
boundary term---and thereby not just the value of the Hamiltonian
but also an associated boundary condition.  Nevertheless these
combinations may still appear rather artificial, as being
mathematically and physically contrived. This situation may be
contrasted with the case of another (nonholonomic) energy-momentum
expression: elsewhere we have shown that the tetrad-teleparallel
energy-momentum gauge current expression \cite{AGP00} {\em
naturally} has the desired Bel-Robinson property \cite{SN08}.

Although it still allows for a certain amount of freedom, the small
vacuum region Bel-Robinson positivity requirement provides a strong
restriction which excludes many otherwise satisfactory
energy-momentum expressions.

\ack We would like to thank the Taiwan NSC for their financial
support under the grant numbers NSC 93-2112-M-008-001,
94-2112-M008-038, 95-2119-M008-027, 96-2112-M-008-005,
97-2112-M-008-001.   JMN was also supported in part by the National
Center of Theoretical Sciences.

\section*{References}

redpajama_set_name: RedPajamaArXiv


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Tag: Chris Hadfield
Richard Branson and Friends Reach the Edge of Space, and Lived to Tell About it!
Early this morning, Sir Richard Branson and Virgin Galactic achieved a major milestone in the development of commercial space travel. Along with a team of specialists, Branson traveled to the edge of space aboard the VSS Unity and made it safely back to Earth. In so doing, Branson and his company have also fired the latest salvo in the ongoing race between the titans of the commercial space industry (aka. NewSpace).
Continue reading "Richard Branson and Friends Reach the Edge of Space, and Lived to Tell About it!"
Cool Photo of Canadarm2 With its Dextre Hand. Oh and the Earth. That's Nice Too.
Check out this image of the Canadian Space Agency's (CSA) Canadarm2 on the International Space Station. The CSA's Dextre is attached to one end of the arm. The Canadarm2 played a vital role in assembling the ISS, while Dextre helps maintain the ISS, freeing astronauts from routine yet dangerous spacewalks, and allowing them to focus on science.
Continue reading "Cool Photo of Canadarm2 With its Dextre Hand. Oh and the Earth. That's Nice Too."
Settle the Moon Before Mars, Says Astronaut Chris Hadfield
In the coming decades, NASA has some rather bold plans for space exploration. By the 2030s, they hope to mount their "Journey to Mars". a crewed mission that will see astronauts traveling beyond Earth for the first time since the Apollo era. At the same time, private companies and organizations like SpaceX and MarsOne are hoping to start colonizing Mars within a decade or so.
According to Chris Hadfield, these mission concepts are all fine and good. But as he explained in a recent interview, our efforts should be focused on renewed exploration of the Moon and the creation of a lunar settlement before we do the same for Mars. In this respect, he is joined by organizations like the European Space Agency (ESA), Roscosmos, the Chinese National Space Agency (CNSA), and others.
When it comes to establishing a base on the Moon, the benefits are rather significant. For starters, a lunar outpost could serve as a permanent research base for teams of astronauts. In the same respect, it would present opportunities for scientific collaboration between space agencies and private companies – much in the same way the International Space Station does today.
On top of that, a lunar outpost could serve as a refueling station, facilitating missions deeper into the Solar System. According to estimates prepared by NexGen Space LLC (a consultant company for NASA), such a base could cut the cost of any future Mars missions by about $10 billion a year. Last, but not least, it would leverage key technologies that have been developed in recent years, from reusable rockets to additive manufacturing (aka. 3D printing).
And as Chris Hadfield stated in an interview with New Scientist, there are also a number of practical reasons for back to the Moon before going to Mars – ranging from distance to the development of "space expertise". For those interested in science and space exploration, Chris Hadfield has become a household name in recent years. Before becoming an astronaut, he was a pilot with the Royal Canadian Air Force (RCAF) and flew missions for NORAD.
After joining the Canadian Space Agency (CSA) in 1992, he participated in two space missions – STS-74 and STS-100 in 1995 and 2001, respectively – as a Mission Specialist. These missions involved rendezvousing with the Russian space station Mir and the ISS. However, his greatest accomplishment occurred in 2012, when he became the first Canadian astronaut to command an ISS mission – Expedition 35.
During the course of this 148-day mission, Hadfield attracted significant media exposure due to his extensive use of social media to promote space exploration. In fact, Forbes described Hadfield as "perhaps the most social media savvy astronaut ever to leave Earth". His promotional activities included a collaboration with Ed Robertson of The Barenaked Ladies and the Wexford Gleeks, singing "Is Somebody Singing?" (I.S.S.) via Skype.
Canadian astronaut Chris Hadfield, the first Canadian to serve as commander of the ISS. Credit: CTV
The broadcast of this event was a major media sensation, as was his rendition of David Bowie's "Space Oddity", which he sung shortly before departing the station in May 2013. Since retiring from the Canadian Space Agency, Hadfield has become a science communicator and advocate for space exploration. And when it comes to the future, he was quite direct in his appraisal that the we need to look to the Moon first.
According to Hadfield, one of the greatest reasons for establishing a base on the Moon has to do with its proximity and the fact that humans have made this trip before. As he stated:
"With long-haul space exploration there is a whole smorgasbord of unknowns. We know some of the threats: the unreliability of the equipment, how to provide enough food for that length of time. But there are countless others: What are the impacts of cosmic rays on the human body? What sort of spacecraft do you need to build? What are the psychological effects of having nothing in the window for months and months? And going to a place that no one has ever been before, that can't be discounted."
In that, he certainly has a point. At their closest – i.e. when it is at "opposition with the Sun", which occurs approximately every two years – Mars and Earth are still very far from each othre. In fact, the latest closest-approach occurred in 2003, when the two planets were roughly 56 million km (33.9 million miles) apart. This past July, the planets were again at opposition, where they were about 57.6 million km (35.8 million miles) apart.
Using conventional methods, it would take a mission between 150 and 300 days to get from the Earth to Mars. Whereas a more fuel-efficient approach (like ion engines) would cost less but take much longer, a more rapid method like chemical rockets would could cost far more. Even with Nuclear Thermal Propulsion (NTP) or the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) concept, the journey could still take 5 to 7 months.
During this time, astronauts would not only be subjected to a great deal of cosmic radiation, they would have to contend with the affects of microgravity. As studies that have been conducted aboard the ISS that have shown, long-term exposure to a microgravity environment can lead to losses in bone density, muscular atrophy, diminished eyesight, and organ damage.
Recent studies have also shown that exposure to radiation while on the surface of Mars would be quite significant. During its journey to Mars, the Curiosity rover recorded that it was subjected to average dose of 1.8 millisieverts (mSv) per day from inside its spaceship – the Mars Science Laboratory. During its first three hundred days on the surface, it was exposed to about 0.67 millisieverts (mSv) per day.
This is about half and one-fifth (respectively) of what people are exposed to during an average here on Earth. While this falls outside of NASA's official guidelines, it is still within the guidelines of other space agencies. But to make matter worse, a new study from the University of Nevada, Las Vegas, concluded that exposure to cosmic rays could cause cell damage that would spread to other cells in the body, effectively doubling the risk of cancer.
The risks of going to the Moon, in contrast, are easy to predict. Thanks to the Apollo missions, we know that it takes between two and three days to travel from the Earth to the Moon. The Apollo 11 mission, for example, launched from the Cape Kennedy on July 16th, 1969, and arrived in lunar orbit by July 19th, 1969 – spending a total of 51 hours and 49 minutes in space. Astronauts conducting this type of mission would therefore be subject to far less radiation.
Artist's impression of a lunar base created with 3-d printing techniques. Credits: ESA/Foster + Partners
Granted, the surface of the Moon is still exposed to significant amounts of radiation since the Moon has no atmosphere to speak of. But NASA estimates that walls which are 2.5 meters in thickness (and made from lunar regolith) will provide all the necessary shielding to keep astronauts or colonists safe. Another good reason to go to the Moon first, according to Hadfield, is because expertise in off-world living is lacking.
"There are six people living on the International Space Station, and we have had people there continuously for nearly 17 years," he said. "But the reality is we have not yet figured out how to live permanently off-planet. So I think if we follow the historically driven pattern then the moon would be first. Not just to reaffirm that we can get there, but to show that we can also live there."
But perhaps the best reason to settle the Moon before moving onto Mars has to do with the fact that exploration has always been about taking the next step, and then the next. One cannot simply leap from one location to the next, and expect successful results. What are required is baby-steps. And in time, sufficient traction can be obtained and the process will build up speed, enabling steps that are greater and more far-reaching. Or as Hadfield put it:
"For tens of thousands of years humans have followed a pattern on Earth: imagination, to technology-enabled exploration, to settlement. It's how the first humans got to Australia 50,000 or 60,000 years ago, and how we went from Yuri Gagarin and Alan Shepherd orbiting Earth to the first people putting footprints on the moon, to people living in orbit.
Based on this progression, one can therefore see why Hadfield and others beleive that the next logical step is to return to the Moon. And once we establish a foothold there, we can then use it to launch long-range missions to Mars, Venus, and beyond. Incremental steps that eventually add up to human beings setting foot on every planet, moon, and larger body in the Solar System.
On the subject of lunar colonization, be sure to check out our series on Building a Moon Base, by Universe Today's own Ian O'Neill.
Further Reading: New Scientist
Ride Shotgun Through the Solar System with Chris Hadfield
It sounds like a space nerd's dream come true: riding in a Tesla with former astronaut Chris Hadfield, doing a science version of Carpool Karaoke. And to top it off, you're driving through the Solar System.
A new film out called "Miniverse" via CuriosityStream takes you on a ride through a scaled-down version of our Solar System. It's similar to other scaled solar system models — which make the huge distances in our cosmic neighborhood a little less abstract — like the Voyage Scale Model Solar System in Washington, DC, the Sagan Planet Walk in Ithaca, New York or the Delmar Loop Planet Walk in St. Louis, Missouri.
But this is bigger. In the Miniverse, various points across the continental United States indicate scaled distances between the planets.
Here's the trailer:
The first leg of the trip takes viewers on a journey from the Sun all the way to Mars. In the scaled down solar system, that's only the distance from Long Island to the other side of New York City. In the sky, Mars appears over the Freedom Tower in New York, and Jupiter towers above the Lincoln Memorial.
Then later, as distances between planets stretch out, the gas giants and ice giants spread across the mid-section of the US. Even our friend Pluto appears over the Pacific Ocean off the West Coast of California.
Astronaut Chris Hadfield and astronomer Laura Danly view Pluto from Santa Monica, California, in a scene from 'Miniverse'. Credit: CuriosityStream.
Your traveling companions are pretty awesome.
Behind the wheel for the entire adventure is the funny and engaging Chris Hadfield. He's joined by a distinguished band of interstellar hitchhikers: famed theoretical physicist Dr. Michio Kaku, as well as Derrick Pitts, Chief Astronomer at the Franklin Institute in Philadelphia, and Dr. Laura Danly, Curator of the Griffith Observatory in Los Angeles. Along the way, Hadfield poses questions to his guests about the various bodies in our solar system.
"The big takeaway is just how vast the distances are in the solar system," Danly told Universe Today via email. "Every time we look at a drawing of our solar system it reinforces the wrong image in our minds. In reality, the planets are small and the distances are vast. Anyone who has driven cross-country knows that those miles get very long, day after day. So Miniverse provides a visceral feeling to just how great those distances are."
A GPS-like view of the first leg of the trip through the Miniverse. Credit: CuriosityStream.
If you already have a CuriosityStream account, you can watch the film here. If you don't, you can take advantage of a 30-day free trial in order to watch Miniverse, and all the other great science offerings available, such as Stephen Hawking's Universe, Brian Cox's Wonders of Life, and other topics from astronomy observing tips to info about various missions to theoretical physics. Check it out. If you're interested in continuing after your free trial, the ad-free streaming service costs $2.99, $5.99 and $11.99 per month for standard definition, high definition, and ultra high definition 4K respectively.
We suggested to the CuriosityStream folks of putting physical markers along this path across the US, which would really make a great cross country road trip. Come along for the ride!
Posted on June 4, 2015 April 28, 2017
Who Are The Most Famous Astronauts?
There have been many astronauts who have made tremendous contributions to our knowledge of space. But asking "who is the most famous?" is somewhat tricky. For one, its a bit subjective. And second, it can be hard to objectively measure just how important and individuals contributions really are. Surely, all astronauts are deserving of recognition and respect for their bravery and contributions to the pursuit of knowledge.
Nevertheless, in the course of human space exploration, some names do stand out more than others. And some have made such immense contributions that their names will live on long after we too have passed away. So without further ado, here are just a few of the most famous astronauts, along with a list of their accomplishments.
Yuri Gagarin:
As the first man to ever go into space, no list of famous astronauts would be complete without Yuri Gagarin. Born in the village of Klushino in the Smolensk Oblast on March 9th, 1934, Gagarin was drafted into the Soviet Air Force in 1955 and trained in the use of jet fighters. In 1960, he was selected alongside 19 other pilots to join the newly-formed Soviet Space Program.
Yuri Gagarin before a space flight aboard the Vostok 1 spacecraft, April 12th, 1961. Credit: RIA Novosti
Gagarin was further selected to become part of the Sochi Six, an elite group of cosmonauts who formed the backbone of the Vostok program. Due to his training, physical size (as the spacecraft were quite cramped), and favor amongst his peers, Gagarin was selected to be the first human cosmonaut (they had already sent dogs) to make the journey.
On April 12th, 1961, Gagarin was launched aboard the Vostok 1 spacecraft from the Baikonur Cosmodrome, and thus became the fist man to go into space. During reentry, Gagarin claimed to have whistled "The Motherland Hears, The Motherland Knows", and reportedly said, "I don't see any God up here" when he reached suborbital altitude (which was falsely attributed).
Afterwards, he toured the world and became a celebrity at home, commemorated with stamps, statues, and the renaming of his ancestral village to Gagarin. The 12th of April is also known as "Cosmonauts Day" in Russia and many former Soviet-states in his honor.
Gagarin died during a routine training exercise in March 27th, 1968. The details of his death were not released until June of 2013, when a declassified report indicated that Gagarin's death was caused by the error of another pilot.
Alan B. Shepard Jr.:
In addition to being an astronaut and one of the Mercury Seven – the first seven pilots selected by NASA to go into space – Shepard was also the first American man to go into space. He was born November 18th, 1923 in Pebble, California and graduated from the United States Naval Academy with a Bachelor of Science degree. While in the Navy, Shepard became a fighter pilot and served aboard several aircraft carriers in the Mediterranean.
Alan Shepard prepares for his historic flight on May 5, 1961. Credit: NASA
In 1959, he was selected as one of 110 military test pilots to join NASA. As 0ne of the seven Mercury astronauts, Shepard was selected to be the first to go up on May 5th, 1961. Known as the Freedom 7 mission, this flight placed him into a suborbital flight around Earth. Unfortunately, Alan was beaten into space by Soviet cosmonaut Yuri Gagarin by only a few weeks, and hence became the first American to go into space.
Shepard went on to lead other missions, including the Apollo 14 mission – which was the third mission to land on the Moon. While on the lunar surface, he was photographed playing a round of golf and hit two balls across the surface. After leaving NASA, he became a successful businessman. He died of leukemia on July 21st, 1998, five weeks before the death of his wife of 53 years.
Valentina Tereshkova:
Another famous Russian cosmonaut, Tereshkova is also internationally renowned for being the first woman to go into space. Born in the village of Maslennikovo in central Russia on March 6th, 1937, Tereshkova became interested in parachuting from a young age and began training at the local aeroclub.
After Gagarin's historic flight in 1961, the Soviets hopes to also be the first country to put a woman into space. On 16 February 1962, Valentina Tereshkova was selected to join the female cosmonaut corps, and was selected amongst hundreds to be one of five women who would go into space.
In addition to her expertise in parachuting (which was essential since Vostok pilots were to parachute from the capsule after reentry), her background as a "proletariat", and the fact that her father was a war hero from the Russo-Finnish War, led to her being selected.
Soviet Cosmonaut Valentina Tereshkova photographed inside the Vostok-6 spacecraft on June 16, 1963. Credit: Roscosmos
Her mission, Vostok 6, took place on June 16th, 1963. During her flight, Tereshkova orbited Earth forty-eight times, kept a flight log and took photographs that would prove useful to atmospheric studies. Aside from some nausea (which she later claimed was the result of spoiled food!) she maintained herself for the full three days and parachuted down during re-entry, landing a bit hard and bruising her face.
After returning home, Tereshkova went on to become a cosmonaut engineer and spent the rest of her life in key political positions. She married fellow cosmonaut Andrian Nikolayev and had a daughter. After her flight, the women's corps was dissolved. Vostok 6 was to be the last of the Vostok flights, and it would be nineteen years before another woman would go into space (see Sally Ride, below).
John Glenn Jr.:
Colonel Glenn, USMC (retired) was a Marine Corps fighter pilot and a test pilot before becoming an astronaut. Due to his experience, he was chosen by NASA to be part of the Mercury Seven in 1959. On February 20, 1962, Glenn flew the Friendship 7 mission, and thus became the first American astronaut to orbit the Earth and the fifth person to go into space.
John Glenn enters his Friendship 7 spacecraft on On Feb. 20, 1962. Credit: NASA
For his contributions to spaceflight, John Glenn earned the Space Congressional Medal of Honor. After an extensive career as an astronaut, Glenn retired from NASA on January 16th, 1964, to enter politics. He won his first bid to become a US Senator in 1974, representing Ohio for the Democratic Party, and was reelected numerous times before retiring in January of 1999.
With the death of Scott Carpenter on October 10, 2013, he became the last surviving member of the Mercury Seven. He was also the only astronaut to fly in both the Mercury and Space Shuttle programs – at age 77, he flew as a Payload Specialist on Discovery mission (STS-95). For his history of service, he was awarded the Presidential Medal of Freedom in 2012.
Neil Armstrong:
Neil Armstrong is arguably the most famous astronauts, and indeed one of the most famous people that has ever lived. As commander of the historic Apollo 11 mission, he will forever be remembered as the first man to ever walk on a body other than Earth. Born on August 5th, 1930, in Wapakoneta, Ohio, he graduated from Purdue University and served the National Advisory Committee for Aeronautics High-Speed Flight Station before becoming an astronaut.
Neil A. Armstrong inside the Lunar Module after EVA. Credit: NASA
In accordance with the Holloway Plan, Neil studied at Purdue for two years and then committed to three years of military service as a naval aviator before completing his degree. During this time, he trained in the use of jet aircraft and became a test pilot at Andrews Air Force base, meeting such personalities as Chuck Yeager.
In 1962, when NASA was looking to create a second group of astronauts (after the Mercury 7), Armstrong joined and became part of the Gemini program. He flew two missions, as the command pilot and back-up command pilot for Gemini 8 and Gemini 11 (both in 1966), before being offered a spot with the Apollo program.
On July 16th, 1969, Armstrong went into space aboard the Apollo 11 spacecraft, alongside "Buzz" Aldrin and Michael Collins. On the 20th, after the lunar module set down on the surface, he became the first person to walk on the Moon. As he stepped onto the lunar surface, Armstrong uttered the famous words, "That's one small step for a man, one giant leap for mankind."
After retiring from NASA in 1971, Armstrong completed his master's degree in aerospace engineering, became a professor at the University of Cincinnati, and a private businessman.
On Augusts 25th, 2012, he died at the age of 82 after suffering complications from coronary artery bypass surgery. On September 14th, his cremated remains were scattered in the Atlantic Ocean during a burial-at-sea ceremony aboard the USS Philippine Sea.
For his accomplishments, Armstrong was awarded the Presidential Medal of Freedom, the Congressional Space Medal of Honor, and the Congressional Gold Medal in 2009.
James Lovell Jr.:
Lovell was born on March 25th, 1928 in Cleveland, Ohio. Like Shepard, he graduated from the US Naval Academy and served as a pilot before becoming one of the Mercury Seven. Over the course of his career, he flew several missions into space and served in multiple roles. The first was as the pilot of the Apollo 8 command module, which was the first spacecraft to enter lunar orbit.
He also served as backup commander during the Gemini 12 mission, which included a rendezvous with another manned spacecraft. However, he is most famous for his role as commander the Apollo 13 mission, which suffered a critical failure en route to the Moon but was brought back safely due to the efforts of her crew and the ground control team.
Lovell is a recipient of the Congressional Space Medal of Honor and the Presidential Medal of Freedom. He is one of only 24 people to have flown to the Moon, the first of only three people to fly to the Moon twice, and the only one to have flown there twice without making a landing. Lovell was also the first person to fly in space four times.
Original crew photo, (left to right) Jim Lovell, Thomas K. Mattingly, and Fred W. Haise. Credit: NASA
Dr. Sally Ride:
Sally Ride became renowned in the 1980s for being one of the first women to go into space. Though Russians had already sent up two female astronauts – Valentina Tereshkova (1963) and Svetlana Savitskaya (1982) – Ride was the first American female astronaut to make the journey. Born on May 26th, 1951, in La Jolla, California, Ride received her doctorate from Stanford University before joining NASA in 1978.
On June 18th, 1983, she became the first American female astronaut to go into space as part of the STS-7 mission that flew aboard the space shuttle Challenger. While in orbit, the five-person crew deployed two communications satellites and Ride became the first woman to use the robot arm (aka. Canadarm).
Her second space flight was in 1984, also on board the Challenger. In 1986, Ride was named to the Rogers Commission, which was charged with investigating the space shuttle Challenger disaster. In 2003, she would serve on the committee investigating the space shuttle Columbia disaster, and was the only person to serve on both.
Sally Ride communicates with ground controllers from the flight deck during STL-7 in 1983. Credit: U.S. National Archives and Records Administration
Ride retired from NASA in 1987 as a professor of physics and continued to teach until her death in 2012 from pancreatic cancer. For her service, she was given numerous awards, which included the National Space Society's von Braun Award, two NASA Space Flight Medals, and was inducted into the National Women's Hall of Fame and the Astronaut Hall of Fame.
Chris Hadfield:
Last, but certainly not least, there's Chris Hadfield, the Canadian astronaut, pilot and engineer who became famous for his rendition of "Space Oddity" while serving as the commander of the International Space Station. Born on August 29th, 1959 in Sarnia, Ontario, Hadfield became interesting in flying at a young age and in becoming an astronaut when he watched the televised Apollo 11 landing at age nine.
After graduating from high school, Hadfield joined the Canadian Armed Forces and spent two years at Royal Roads Military College followed by two years at the Royal Military College, where he received a bachelor's degree in mechanical engineering in 1982. He then became a fighter pilot with the Royal Canadian Air Force, flying missions for NORAD. He also flew as a test pilot out of Andrews Air Force Base as part of an officer exchange.
In 1992, Hadfield became part of the Canadian Space Agency and was assigned to NASA's Johnson Space Center in Houston, as a technical and safety specialist for Shuttle Operations Development. He participated in two space missions – STS-74 and STS-100 in 1995 and 2001, respectively – as a Mission Specialist. These missions involved rendezvousing with Mir and the ISS.
Canadian astronaut Chris Hadfield performing his rendition of "Space Oddity". Hadfield is the first Canadian to serve as commander of the ISS. Credit: CTV
On December 19th 2012, Hadfield launched in the Soyuz TMA-07M flight for a long duration stay on board the ISS as part of Expedition 35. He became the first Canadian to command the ISS when the crew of Expedition 34 departed in March 2013, and received significant media exposure due to his extensive use of social media to promote space exploration.
Forbes described Hadfield as "perhaps the most social media savvy astronaut ever to leave Earth". His promotional activities included a collaboration with Ed Robertson of The Barenaked Ladies and the Wexford Gleeks, singing "Is Somebody Singing?" (I.S.S.) via Skype. The broadcast of this event was a major media sensation, as was his rendition of David Bowie's "Space Oddity", which he sung shortly before departing the station in May 2013.
For his service, Hadfield has received numerous honors, including the Order of Canada in 2014, the Vanier Award in 2001, NASA Exceptional Service Medal in 2002, the Queen's Golden Jubilee Medal in 2002, and the Queen's Diamond Jubilee Medal in 2012. He is also the only Canadian to have received both a military and civilian Meritorious Service Cross, the military medal in 2001 and the civilian one in 2013.
Universe Today has interesting articles on Neil Armstrong, "Buzz" Edwin Aldrin, and the enduring legacy of Apollo 11.
If you are looking for more information, you should check out famous aviators and astronauts and astronaut biographies.
Astronomy Cast has an episode on the US space shuttle.
NASA: Alan Shepard Jr
NASA: Neil Armstrong
NASA: John Glenn
NASA: James Lovell Jr.
NASA: Sally Ride
Do Astronauts Drink their Pee?
In order to fly in space, astronauts need to make a few sacrifices, like drink their own urine. Yuck? Don't worry, it's totally safe.
Astronauts are a resourceful bunch. They're the best of the best of the best of the best. They're ready to do whatever it takes to get the job done. WHATEVER IT TAKES, INCLUDING DRINKING PEE. They live on the International Space Station for the better part of a year, where air, food and water are precious resources. Sometimes you take a hit for the team back.
Every drop of water on the International Space Station was carried there from Earth, by rocket, possibly in someone's bladder. The cost of launching a single kilo into orbit can be over $10 grand. Do a little back of the tp math and the value of a single kilogram of water in space is worth almost as much as a kilogram of yellow gold here on Earth.
That's actual money gold, and not pee joke gold. The punchline is astronauts need to conserve water. For the longest time, there wasn't any way to take conservation to the "next level". All the "waste water" including pee produced on the station was just held, possibly uncomfortably and resulting in dancing, and it needed to be disposed of.
In 2009, NASA got serious about conserving water and launched the Water Recovery System to the International Space Station. What is it with you guys and names? I would have shot for "Precycling Internal Solution System" just for the acronym. In fact, that's what we're using now.
Ever since, astronauts have been drinking their own urine like Captain Redbeard Rum on Blackadder. Generally after it's been purified by the recovery system, or if you prefer "peecycled". Outside of that I'm sure accidents happen, and whatever they get up to in their own time is their business.
Speaking of which, Here's a video of beloved Canadian astronaut Chris Hadfield demonstrating the P.I.S.S system. It takes all water vapor, sweat, and grey water produced and excreted by astronauts and turns it back into drinkable water.
On Earth, you can clear dirty water by boiling it. Collect your steam on a cold surface, pure, pee free and ready for drinking again. Pro tip, this process actually requires gravity, which isn't readily available when you're in free fall.
The Recovery System looks like a big spinning keg, which creates artificial gravity. It's heated and steam is produced. Dirt and contaminants such as the most purified pee molecules are pushed to the edges of the drum while the steam is carried away.
NASA's Water Recovery System. Credit: NASA
The artificial gravity isn't perfect, and only 93% of the water can be recovered this way. This means that dirty waste water builds up inside the space station and needs to be flushed with the rest of the trash. Astronauts can't peecycle everything on the space station, trash does build up. They've got a solution for this too.
The most recent cargo delivery spacecraft is always left attached to the space station. Instead of doing laundry, which would use up their precious water and is super boring. Seriously, if you went to the trouble of sending me to space and asked to me wash my clothes I'd get a little snippy.
Astronauts do what the rest of us only dream about. They just wear their clothes until they're totally worn out. Then throw their laundry into the excess module. Once it's completely filled with pee, laundry, food remnants, and other, uh… stuff, the spacecraft detaches from the station and re-enters the Earth's atmosphere where it's incinerated. No fuss, no muss. Also, clearly for this episode, we're only going as far as pee jokes as poop jokes are off the table.
Yes, astronauts are drinking their pee. They close their eyes and remind themselves it's just pure water. Completely safe and delicious to drink. No pee molecules left here. As astronaut Koichi Wakata said, "Here on board the ISS, we turn yesterday's coffee into tomorrow's coffee".
Would you be willing to drink the water produced by the Water Recovery System? Tell us in the comments below.
Podcast (audio): Download (Duration: 4:13 — 3.9MB)
Podcast (video): Download (Duration: 4:36 — 54.7MB)
Space-y Charity: Some Ideas To Respond To Astronaut Hadfield's Challenge
While the world was enchanted with Chris Hadfield's social media posts last year, a new video has the retired astronaut talking about loftier things. Say, for example, how humanity landed a camera on the Saturn moon Titan back in 2005. Or to be more practical, the fact that smallpox was eradicated in its naturally occurring form.
In his talks and books, Hadfield describes himself as one who never focuses on complaining. He was almost yanked from his command of the International Space Station due to a medical issue, but he pressed on and convinced the doctors to let him fly. And in this new video, he focuses on what humans do generally to make the world better — imperfect as it is.
"There are problems with everything, and nothing's perfect, but that shouldn't be cause to moan. That should be cause to achieve. Our world is a better place than we often claim it to be," Hadfield said. "We live the way we do," he added, "because people chose to tackle their problems, head on."
The video appears to have a heavy emphasis on the Bill & Melinda Gates Foundation, a gigantic philanthropic network that works to improve lives in the developing world and also for the disadvantaged in the United States. But there are many ways to give back to your community, even through gestures as simple as volunteering.
Here are some examples in the space world (note that these aren't necessarily endorsements for the organizations, but just ideas for making contributions in space and astronomy):
Cosmoquest, which runs online astronomy courses and also allows citizens to map extraterrestrial bodies right alongside astronomers.
Astronomers Without Borders brings astronomy education across the world, particularly to developing countries.
Uwingu says that half of its donations goes to grants to support learning in astronomy.
Other examples of space-y charity could include volunteering or donating to a local school or university, joining one of the numerous volunteer organizations in astronomy, or getting involved in a space advocacy group.
NASA SoundCloud Sounds Aim To Bring Music To The Final Frontier
Fancy having a shuttle launch play as your ringtone? NASA is trying to make that possible through offering several dozen space sounds on SoundCloud, a popular music- and sound-sharing service.
In the last month, the agency has uploaded 63 sound files ranging from objects in the solar system, to rocket launches, to famous quotes from NASA's history. And you can download and use the files for free from here, as long as you follow the usage guidelines over here.
"Here's a collection of NASA sounds from historic spaceflights and current missions. You can hear the roar of a space shuttle launch or Neil Armstrong's 'One small step for (a) man, one giant leap for mankind' every time you get a phone call if you make our sounds your ringtone. Or, you can hear the memorable words 'Houston, we've had a problem,' every time you make an error on your computer," the agency wrote on SoundCloud.
Space isn't a foreign entity to SoundCloud, which also hosted dozens of sounds uploaded by prolific social-media sharing Chris Hadfield when the Canadian astronaut went into space between 2012 and 2013. He put up a few songs as well as what certain activities sound like on the International Space Station, such as dinnertime or a spaceship docking.
Retired Astronaut Chris Hadfield Releases Stunning Space Photos
Orbiting 200 miles above the Earth, Retired Astronaut Chris Hadfield could easily photograph the ridges of the Himalayan Mountains, the textures of the Sahara Desert and the shadows cast by the tallest buildings in Manhattan.
Mauritania, also known as the Eye of the Sahara, is a landmark in the vast 3,600,000-square-mile desert. Credit: Chris Hadfield / NASA
"The view of the world when you have it just right there through the visor of your helmet is overpoweringly gorgeous," said Hadfield, speaking Oct. 14 at the American Museum of Natural History in New York City. "It is phenomenal. The world is pouring by with all its colors and textures so fast."
Although Hadfield has already shared many of his photos via social media, he unveiled another 150 images in his latest book, "You Are Here: Around The World in 92 Minutes." The photographs open a rare window onto the Earth, illuminating our planet's beauty and the consequences of human settlement.
The book is designed to replicate a single 92-minute orbit aboard the International Space Station. "It's as if you and I are sitting at the window of the space station, and I said, 'let's go around the world once. I want to show you the really cool stuff,' " said Hadfield.
The astronaut, famed for his zero-gravity rendition of David Bowie's "Space Oddity," took approximately 45,000 photos during his 146-day stint on the space station in 2013. That's roughly 300 photos per day every day. Since NASA does not set aside specific time slots for astronauts to take photos, Hadfield did so while he should have been asleep or serenading millions with his guitar.
The Himalayan mountain range in South Asia. Credit: Chris Hadfield / NASA
Why? Beauty triggers an unexplained emotional reaction, explained Hadfield. It also provides the best means of communication. Although the space station is an incredible scientific laboratory, art is equally important, he added, because it's a way to reach people who might not otherwise be interested in the scientific nitty-gritty.
Hadfield is often attributed for humanizing space travel in a way that others before him had not. His use of social media, videos designed to quench our curiosity about living in space, and music, demonstrate a sheer passion that has inspired millions.
Manhattan awake at 9:23 a.m. local time, and Manhattan at rest at 3:45 a.m. local time. Credit: Chris Hadfield / NASA
His photos not only share the natural beauty of our home planet, but also many signs of humanity, from bright city lights to the devastations of climate change as lakes dry up and disappear. "There's so much information in just one glimpse out the window of human decision making and geology," said Hadfield.
Hadfield's remote yet vivid photos stand as a reminder of both the magnificence and fragility of life on our planet. "To have the world on one side, like this huge kaleidoscope, and then the bottomlessness of the Universe right there beside you," said Hadfield, trailing off in awe. "You're not on the world looking at it. You're in the Universe with the world."
Is A Sitcom Astronaut Hadfield's Next Frontier? ABC Comedy In The Works, Report Says
It's possible that Chris Hadfield's best-selling book will become a sitcom! The astronaut who quickly became the world's most-wanted Canadian last year, based on his amusing YouTube videos and stunning space pictures, is involved in production of a sitcom based on An Astronaut's Guide To Life On Earth, Deadline reports.
"The TV series is described as a family comedy about an astronaut who is back from space and finds that re-entering domestic life might be the hardest mission he's ever faced," wrote Deadline. Hadfield is slated to be the consulting producer on the show, which has been approved for pilot production.
Hadfield made headlines during his third and final spaceflight in 2012-13, part of which saw him was commander of the International Space Station's Expedition 35. His five-month flight in space saw his Twitter numbers soar as he virtually hobnobbed with celebrities and worked social media every day, with the help of his son Evan. (This was done in between running one of the most scientifically productive missions on the station ever.)
Chris Hadfield in the Cupola of the ISS. Credit: NASA
Weeks after returning to Earth, Hadfield retired from the Canadian Space Agency. His second book, You Are Here: Around the World in 92 Minutes, is expected to be released in October.
Space is a serious business, but there are some comedies associated with it. Former NASA astronaut Mike Massimino has been a repeat guest on The Big Bang Theory, particularly when one of the main characters went into space. NBC is also working on a sitcom called Mission Control, which describes the challenges of a female aerospace engineer trying to make her way in the male-dominated field of the 1960s.
ABC also is taking space to a more serious side, as it is expected to make a miniseries based on the Lily Koppel bestseller The Astronaut Wives Club — a look at the wives of the first astronauts in the 1960s.


Sophia Tong over at the Gamespot Sound Byte blog has a fine video interview up with 'Dragon Age: Origins' composer Inon Zur.
From Power Rangers to Digimon, and Fallout 3 to Dragon Age: Origins, award-winning composer Inon Zur has worked on video games, movie trailers, television, anime, and film. With more than 40 video games already under his belt, he is currently working on the music for Fallout: New Vegas as well as several other unannounced projects.


September is national Life Insurance Awareness Month. And while it's important to consider life insurance throughout the entire year, this "holiday" can be extra motivation to re-evaluate your current policy — or more importantly, look into buying one if you haven't already. Here are some basic considerations.
If you're young or don't have significant assets, you may think you don't need life insurance. But life insurance is for everyone. It can help cover funeral and burial costs, and can help pay down any debts you owe so your loved ones aren't left holding the bag. It can also provide a cash cushion for your loved ones to draw from as they adjust to life without you or your income. There are several different types of life insurance you can choose from to best fit your personal situation.
Your life insurance needs will depend on a number of factors, including the size of your family, your financial obligations, your career stage, and your goals. For example, when you're young, you may not need a large amount of life insurance. However, as you take on more responsibilities and your family grows, your need for life insurance grows too.
What immediate financial expenses (such as debt repayment or funeral expenses) would your family face upon your death?
How much of your salary goes toward paying current expenses and future household needs?
How long would your dependents need support if you were to pass away?Do you want to leave money for other uses upon your death? Examples include funding your children's education, gifts to charities, or inheritances.
Who will benefit from your policy?
When you buy life insurance, you'll name a primary beneficiary to receive the proceeds of your insurance policy. Your beneficiary may be a person, corporation, or other legal entity. You can name multiple beneficiaries and specify what percentage of the net benefit each one will receive. If you name your minor child as a beneficiary, you should also designate an adult as the child's guardian in your will.
Once you purchase a life insurance policy, periodically review your coverage. Over time, your needs will change, and you should adjust your coverage accordingly. In addition, keep a close eye on if and when your policy expires. In some cases, if you let your policy lapse, it might cost you more to buy a new policy, even if it has the same amount of coverage.
Anytime is a good time to think about life insurance — but September being National Life Insurance awareness month can be extra motivation to take another look at your current policy or explore buying a policy if you don't yet have one. Taking these key steps now can go a long way in helping to protect your loved ones in the future.
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Clinton, Arkansas > Business Industries: Yellow Pages Directory Inc.
Clinton is located in the County of Van Buren. Industries involved in aviation, automotive, finance, apparel, information technology, healthcare services, agro, real estate and telecom serve as the backbone for the economic development of the city. Majority of the workforce is also associated with services related to truck repairing, rehabilitation, mailing and shipping and rental agencies also contribute to the economic viability of the city.


Visit their website » The people at Wasa strive to be the best producer of crisp bread in the world. In a timespan of only one year people together consume about 60k tons of crips bread.
In Sweden they eat the most crisp bread, on average about 4 kilo per person per year! The biggest markets outside of Sweden are the other Scandinavian countries and Germany, followed by Poland, Holland, France and the United States. But even if you don't find yourself in any of these countries I just mentioned, you can probably still get Wasa crisp bread there.
Wasa is part of parent company Barilla. The Barilla organization has about 18k employees and has a yearly turnover of 4,2 billion Euro's.
Pietro Barilla had a dream when he opened his small pastry shop in Parma, Italy. This happened in the year 1877. His dream was to provide the people in his neighbourhood with the freshest, most tasty food that people were able to enjoy with family and friends at home. What he didn't know at that time that this was the start of a huge company that 125 years later would be the best selling producer of premium pasta, as well as the premium producer of pasta sauces in Central Europe along with the biggest bakery products in Italy and crisp breads in Scandinavia.


3    Pent,  Gen   31:   39(7)|       the ancient Near East, as recorded in the Code of Hammurabi: "
7    Pent,  Jos    8:   31   |         servant of the LORD, as recorded in the book of the law.
13     His, 1Kin   10:    1(1)|      rulers among the Arabs are recorded in eighth-century- B.C.
56    Gosp,  Act   20:   16(5)|       of Jesus (Acts 20:35) not recorded in the gospel tradition.


Usually, Canada Revenue Agency doesn't give you many second chances. But rules on when you can contribute to RRSPs and use RRSP tax deductions are suprisingly flexible. Understanding them can really save tax!
What if I don't use all my RRSP contribution limit?
Unused contribution room can be carried forward to use in any future year. However, you cannot contribute to an RRSP for a person (yourself or your spouse) who already turned age 71 in the previous year.
Do I have to immediately deduct all my RRSP contributions?
No. You can choose when to deduct them, to maximize your tax savings. Deduct them now, or in a future year, or even divide them between years. See these examples to see how waiting to deduct contributions may increase your tax savings.
Can I catch up once retired?
Yes. Many people forget they can contribute even without current earned income (for example, after retiring). If you have unused RRSP contribution room from past years and funds available, contributing to your own or your spouse's RRSP is allowed up until the end of the year the planholder turns age 71.
But watch out for special situations where contributing to an RRSP may not make sense. For example, where you'll lose eligibility for the Guaranteed Income Supplement (GIS), or your tax rate when withdrawing in retirement will be much higher than your initial tax savings. Other options, such as a Tax Free Savings Account (TFSA), might be more appropriate for your circumstances. See Mortgage or RRSP or TFSA for more.
A Vancity investment professional can help you create a plan to catch up on unused RRSP contribution room. To speak with an investment professional, contact 604.709.5955 or visit your local community branch in your neighborhood.


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Dr. Bruno Linder Tallahassee – Bruno Linder was born in Sniatyn, Poland, on September 3, 1924. He lived in Curacao, West Indies from 1933 until 1946 when he arrived in the US. He received his PhD in chemistry from UCLA and was a Professor of Chemistry at FSU from 1957 until his retirement in 1998. Bruno was…
Sunday, January 13, 2019 "Jeff Goldman covering the Whitehouse From Reagan to Trump: an Insider's Retrospective Mr. Goldman, has been an eyewitness to the major historical events. He has covered 6 wars and military conflicts. In the Middle East, he covered both Gulf Wars. He lived in Kuwait and Saudi Arabia for many months during…
2019 Summer Camp Scholarship Information
The 2019 application for the Tallahassee Jewish Federation Al Sulkes Scholarship Program for Overnight Summer Camps and Israel Programs is now open. Please review the application criteria and procedures in the downloadable form here: http://bit.ly/TJFcampscholarship All applications must be submitted by January 25, 2019 to the Tallahassee Jewish Federation, Attention Camp Scholarships, P.O. Box 14825…
Jewish Heritage Week in Tallahassee!
Senator Daphne Campbell Seeks to Declare Jewish American Heritage Week Aiming to broaden recognition of the rich history and culture Jewish Americans have contributed to North America and the state of Florida, state Senator Daphne Campbell (D- District 38) on Tuesday filed a resolution declaring the week of February 12th as Jewish American Heritage week in Florida….
2018 The Tallahassee Jewish Federation – CAMPAIGN KICKOFF
The Tallahassee Jewish Federation – CAMPAIGN KICKOFF Invites you to attend a presentation by Nir Buchler Opportunities and Challenges Facing the Jewish World, How the Jewish Agency is Impacting the Future of the Jewish People Sunday, January 28, 2018 3:00-5:30 PM Food Glorious Food 1950 Thomasville Road, Tallahassee Edibles and libations will be served Nir Buchler was…
Jewish Film Expert to Speak in Tallahassee
Press Release FOR IMMEDIATE RELEASE: October 31, 2016 FOR MORE INFORMATION: Allen Grossman, Program Coordinator Jewish Film Expert to Speak in Tallahassee Dr. Eric Goldman is one of the world's foremost scholars of Jewish, Yiddish and Israeli cinema. He is adjunct professor of cinema at Yeshiva University and film critic for New Jersey's The Jewish Standard….
Anne Frank: A History for Today
The Museum of Fine Arts, Florida State University, announces Anne Frank: A History for Today opening on January 4 and closing February 7, 2016. All exhibitions & receptions are free & open to the public. Anne Frank: A History for Today was developed by the Anne Frank House and is sponsored in North America by The Anne Frank Center USA….
JDC trip to Cuba
The Joint Distribution Committee together with the Jewish Federations of North America are sponsoring an historic opportunity to visit the Jewish community in Cuba from Wednesday, October 26 – Sunday October 30, 2016. Please see the attached brochure for more details. For additional information contact Sam Kimelman at 850-264-3480.
JFNA Mission to Israel trip
The Network is offering a Mission to Israel from Monday, April 4th through Sunday, April 10th, 2016. The cost is $2,990 per person, double occupancy, two nights in Tel Aviv, one night in Mitzpe Ramon and three nights in Jerusalem. The Mission will see first-hand our signature programs of PACT in Lod and Lunch and Learn…
Tallahassee Jewish Families Meetup Group
The Jewish Families Meetup Group is a general meetup group for Jewish families in the Tallahassee area, regardless of synagogue affiliation (whether Shomrei, Chabad, Temple Israel or no synagogue at all). It's primarily geared toward families with kids, and the meetups will range from playdates to park outings to movies to book readings to arts…
The Network's Facebook Page!
The JFNA National Network of Independent Communities has a new Facebook Page. We need your help to build our presence in the Network. Here are some easy was to start: · Check out our page soon and often! · When you see our posts in your newsfeed, click on them to read further · Take a look at…
BBJSC – Brunch and a Movie
What do a Polish Rabbi, Cowboys and Indians have in common? Nothing but hilarious adventures and some soul searching. Come see Gene Wilder and Harrison Ford in "The Frisco Kid" and enjoy some lox, bagels and cream cheese with your friends in the Jewish community. THE BIG BEND JEWISH SOCIAL CLUB invites you to Brunch…


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Manhunt Underway For Convict Who Kidnapped, Tortured Women Jan 27, 2023
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A simple Google search for "credit repair myths" returns over 300,000 results. I guess it's pretty safe to say that there are some myths out there about credit repair. Some of the more popular ones like "credit repair is illegal" and "credit repair doesn't work" are absolutely false. Others, like "credit repair agencies are all scams" and "negative items can't be removed if they can be verified" have some truth to them. If you're considering working on repairing your credit, here's what you need to know.
It's probably a good idea to decide what the word "work" means to you. The truth is, that with a bit of effort, follow-through, and persistence, just about any credit report can be repaired to some degree, even if it's only having one item removed. However, more often than not, there can be much greater results, and some result is certainly better than no result at all, especially when it comes to your credit reports.
This one is a little tricky, and it's all because of one little word, "can." In the simplest terms possible, just because an item can be verified doesn't mean that it will be. Under the Federal Fair Credit Reporting Act, a credit bureau has a reasonable amount of time to verify any item that's disputed. This "reasonable" amount of time is generally understood to be 30 days. And let's face it, there are a whole bunch of things that could go wrong and delay the process, incorrect addresses or names, failure of the creditor to respond, I'm sure you can imagine plenty more. So, the bottom line is this: if the bureau is unable to verify the item within 30 days, the disputed item must be removed.
Be wary of agencies that charge any fees in advance, it's against federal law for them to do so.
Avoid firms that guarantee a result, there are factors that they can't control, and guaranteeing a specific result is like a lawyer guaranteeing he can get you acquitted, there's no possible way to accurately predict the outcome.
Although in many cases it's easier and more effective to do so, under federal law, you can do it yourself. Going back to the lawyer analogy above, you can also choose to represent yourself in a court of law, although in most cases, it's a good idea to have someone of experience represent you. Repairing your credit can be time consuming and frustrating, not to mention kind of tricky, an agency or firm that has experience with the ins and outs can save a whole lot of time and effort, and many times is worth the modest fee they charge.
Although those are both good steps, the fact is that just because a delinquent account, or even an account that has gone to collections, has been brought current and paid off doesn't necessarily mean it will no longer hurt your credit report; these items can continue to be reported for up to seven years. And although making payments on time is always a good idea, payment history only accounts for about 35% of your overall score, and it can take a long time to affect your credit score by doing nothing more than paying on time every month. Which leads us to our last myth.
The truth is, there are a number of factors that determine your credit score, and simply removing all of the negative items won't give you a "perfect" score. In fact, sometimes removing a negative account can actually damage your score. You see, one of the factors in figuring your credit score is length of history. If you have an account that's several years old and has a late payment or two a few years back, it may be a better idea to leave the item alone.
The important thing to remember when considering repairing your credit is that bad credit can cost you thousands and thousands of dollars in higher interest rates every year. You can repair your credit yourself, and there's plenty of information readily available on the web to help you, and lots of "how-to" books on the subject as well. And, there is always the option of hiring a reputable firm to work on repairing your credit, there's just no replacement for an experienced firm working on your behalf.