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"  The battle in Washington over NASA&amp;#039;s future budget has abated\u2014but without resolution. There is currently no settled authorization bill for the space agency, though many think that the compromise hammered out in the Senate a couple of weeks ago will form the basis for next year, and that the House bill, with its draconian cuts to commercial space and its attempt to restore Constellation, is dead..though there will be attempts to revive it when Congress returns to town next month. No one can know for sure, of course, and it may not be resolved until next year with the next Congress, which may result in dramatic changes in the president&amp;#039;s policy. But amidst the uncertainty, what are the possibilities? The two big questions are (1) what will the new 70-ton heavy-lift vehicle demanded by Florida&amp;#039;s Sen. Bill Nelson look like and (2) how will NASA get its astronauts to orbit?  The original administration budget, announced in February, had cancelled the Ares I rocket (planned to lift the Orion lunar crew module), and, given its technical, time and cost issues, it will probably remain dead despite the House attempt to revive it last week. But the administration also committed to development of some sort of heavy-lift vehicle, to commence no later than 2015. This wasn&amp;#039;t soon enough for the Senate, which demanded a new start next year.  In addition to the 70-ton payload requirement, the &amp;quot;Nelson rocket&amp;quot; is also supposed to use shuttle Solid Rocket Boosters (SRBs) and launch infrastructure. In other words, the intent is to build a shuttle-derived system, which may not save much money in terms of operations but preserves the maximum amount of jobs in Florida and Utah (where the SRBs are manufactured). But the wording of the Senate language leaves some wiggle room, with liberal use of the words &amp;quot;where practicable.&amp;quot; In other words, NASA will be performing trade studies next year, and the result may be that what the Senate has in mind is not practicable, freeing the agency up to start other concepts. Concept 1: Shuttle-Derived  There are two generic versions for a shuttle-derived plan\u2014&amp;quot;side mount&amp;quot; and &amp;quot;in line.&amp;quot;  The former, also known as the old shuttle-C concept from the eighties (and updated last year for a presentation to the Augustine panel) is the simplest to develop, because it is basically the same stack as the shuttle, except the orbiter is replaced by a propulsion module and payload bay, using the space shuttle main engines (SSME). This preserves existing structural load paths, and requires the minimum amount of new engineering and modifications to ground facilities. The propulsion module may or may not be recovered, depending on the results of trade studies that would be a function of (among other things) planned flight rate (with a higher one better able to justify recovery). Its disadvantage is that, if used as a launcher for a crew module, it runs the same risk of foam impact as the orbiter version, though the heat shield would be better protected, being on the bottom of the vehicle, and create a new potential hazard of colliding with the vehicle in the event of an abort.  In-line vehicles, in which the engines are moved to the bottom of the external tank, can provide much more payload, but they are essentially new vehicle developments using existing components (such as the SSME, SRBs and external-tank barrel sections). The payload goes on top of the external tank, which means that the LOX (liquid oxygen) tank on top of it must be reshaped, and its structure must be able to support the payload weight (not a major problem, because the LOX itself weighs hundreds of tons, much more than any conceivable payload). These concepts have also been revisited since the eighties, but the most recent version is the Jupiter rocket, developed by the clandestine DIRECT team at NASA over the past few years. This vehicle would have a capability of approximately 70 tons to a low-inclination low Earth orbit (and that may be the source of Sen. Nelson&amp;#039;s requirement), with a potential hundred-ton capability when an upper stage is employed. One of the missions of this dual-purpose design is crew delivery, though it would have excess performance if that were the only payload.  Either version of a shuttle-derived system has been analyzed using the standard four-segment SRBs. Going to the five-segment version planned for Ares would increase the performance of both. In addition, either would satisfy the political imperatives laid out by the Senate in the past couple of weeks, and preserve a lot of the shuttle-related jobs currently being lost with the planned shuttle retirement. Thus, while their development costs would be lower than all-new alternatives, their operating costs would likely be higher. Concept 2: All-Liquid Vehicles Moving away from a shuttle-derived system opens up many more possibilities, with lower operational costs through elimination of the costly solid-rocket subcontractor chain. In addition, the stacked but unfueled vehicle would weigh much less for transport, because it wouldn&amp;#039;t have the heavy solid boosters attached. (This was becoming a serious problem for the planned Ares V of Constellation. It was so heavy that the road between the Vehicle Assembly Building and the launch pads 39A and 39B required strengthening, and NASA needed a new Supercrawler to handle it.) There are basically three potential concepts (with variants within)\u2014growth Atlas, growth Delta and SpaceX&amp;#039;s Falcon XX.  The growth Atlas, known as Atlas V Phase 2 Heavy, as briefed to the Augustine panel last year, uses three 5-meter-diameter units (core plus two strap-ons) with the same Russian RD-180 LOX/kerosene engines that the current Atlas V uses. Tanks would be built using the tooling for the Delta (both Atlas and Delta are manufactured at the same plant in Decatur, Ala.). The upper stage would use the same LOX/hydrogen RL-10s as the current Atlas Centaur, and it would deliver about 80 tons to LEO.  There are several variations on the so-called Super Delta, which could deliver more payload than Constellation&amp;#039;s Ares V. If they use the current Delta&amp;#039;s RS-68 engine for the lower stage, they would be all-LOX/hydrogen vehicles, and probably require a 10-meter-diameter tank like that for Ares V. If they use instead the RD-180 (a much cheaper engine), the use of kerosene in the lower stages would allow a smaller, standard 8.4-meter tank (like the shuttle external tank). The upper stage would use one or more (depending on configuration) of the new J-2X LOX/hydrogen engine planned for Ares I and Ares V, which means that the vehicle wouldn&amp;#039;t be able to meet the Senate&amp;#039;s 2016 mandate.  Growing either Atlas or Delta would be a win for United Launch Alliance (and perhaps Lockheed Martin or Boeing, if they got the development contract). Pratt &amp;amp;amp; Whitney will do well regardless, because they would manufacture any of the engines other than the RD-180, and continue development of the J2-X if the Delta is grown.  The wild card is SpaceX, which has plans for a Merlin 2 engine, a scaled-up version of its Merline LOX/kerosene engine, 10 of which boosted a Dragon capsule into orbit on a Falcon 9 in early June. The new engine will reportedly be in the same thrust class as the F-1 engine used in the first stage of the Saturn V, and would replace the current cluster of nine Merlin ones used on the Falcon 9. Clustering these would allow the construction of what SpaceX formally calls the Falcon XX, but informally calls the &amp;quot;BFR,&amp;quot; (Big Falcon Rocket, though some think that the F might stand for something else), which would presumably be a Saturn-class vehicle. But the engine itself is viewed as a billion-dollar development, and that project is unlikely to move forward until SpaceX either sees a serious market for it or gets a development contract from NASA.  In any event, what the new launch vehicle will look like, or even whether it will exist at all, will remain unknown for months, until NASA finally gets a budget, and starts to do its trade studies. "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/space/rockets/a6047/what-will-get-nasa-to-space-next/>