<p>According to <a href="https://cneos.jpl.nasa.gov/sentry/details.html#?des=2001%20VB" rel="nofollow noreferrer">the Sentry Risk list</a>, it was removed in 2021. Must not be possible anymore.</p>

CC BY-SA 4.0
2023-06-08T14:47:41.307Z
See https://cneos.jpl.nasa.gov/sentry/intro.html for info on how impact risk is determined, including the new algorithm which was introduced in 2021.
PM 2Ring
CC BY-SA 4.0
2023-06-21T23:40:48.927Z
That was the overwhelming probability, thankfully :)
Dragon
CC BY-SA 4.0
2023-06-22T00:32:56.307Z
22 July 2021, according to https://cneos.jpl.nasa.gov/sentry/removed.html . 
So turns out my answer was "next month"...
Dragon
CC BY-SA 4.0
2023-05-01T08:19:55.280Z
2023-06-06T14:30:08.917Z
2023-06-06T14:30:08.917Z
Andyhasaquestion
<p>The remote chance of an Earth impact in late July 2023 may depend on hitting a small &quot;keyhole&quot; near Venus on 2002-01-09.
<a href="https://newton.spacedys.com/neodys/index.php?pc=1.1.8&amp;n=2001VB" rel="noreferrer">NEODyS</a> gives an 8% chance that 2001 VB even passed within 0.1 au of Venus then.</p>
<p>Elsewhere in the cloud of possibilities are:</p>
<ul>
<li>a miss by 0.17 au in mid July 2023 (<a href="https://minorplanetcenter.net/iau/MPEph/MPEph.html" rel="noreferrer">MPC</a>)</li>
<li>a miss by 0.70 au in late April 2024 (HORIZONS)</li>
<li>a miss by 0.49 au in late June 2024 (<a href="https://newton.spacedys.com/neodys/index.php?pc=1.1.3.0&amp;n=2001%20VB" rel="noreferrer">NEODyS</a>)</li>
</ul>
<p>In any case, this object should be bright enough to recover 2 or 3 months before closest approach to Earth.
The major near-Earth asteroid <a href="https://cneos.jpl.nasa.gov/about/search_program.html" rel="noreferrer">search programs</a> currently detect objects at apparent magnitude 21 or 22.</p>

CC BY-SA 4.0
2021-06-23T01:36:13.067Z
Cool answer! I'm just curious; is the 2002 pass of Venus actually being a proper keyhole for Earth impact in 2023 your view, or have orbital dynamics calculations been published showing this to be the case? ([Do all dangerous asteroids first pass through keyholes?](https://space.stackexchange.com/q/41550/12102) and answer(s) to  [Gravitational keyhole for spacecraft flyby?](https://space.stackexchange.com/q/37273/12102))
uhoh
CC BY-SA 4.0
2021-06-23T01:59:49.820Z
@uhoh That's my guess; I don't see a paper about it. Studies with [OrbFit](http://adams.dm.unipi.it/orbfit/) or [FindOrb](https://www.projectpluto.com/find_orb.htm) are an exercise for the highly motivated reader. :)
Mike G
CC BY-SA 4.0
2021-06-23T01:09:12.390Z
2021-06-23T01:09:12.390Z
Mike G
<p><a href="https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=K01V00B" rel="nofollow noreferrer">2001 VB</a>'s orbit is poorly known but has a two-in-a-billion risk of a collision with the earth in 2023.</p>
<p>Assuming that it <strong>were</strong> on a collision course, when would it be likely to be reacquired? Which telescopes would be most likely to do this? Would the likely reacquisition date change significantly if it is not on a collision course?</p>
<p><a href="https://cneos.jpl.nasa.gov/sentry/details.html#?des=2001%20VB" rel="nofollow noreferrer">https://cneos.jpl.nasa.gov/sentry/details.html#?des=2001%20VB</a></p>
<p><a href="https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&amp;body_group=sb&amp;sstr=2001%20VB" rel="nofollow noreferrer">https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&amp;body_group=sb&amp;sstr=2001%20VB</a></p>

CC BY-SA 4.0
2021-06-22T22:05:18.787Z
Something is weird and doesn't add up with this. The HORIZONS predictions for 2023 July have it over 3 AU away from the Earth and super faint but the close approach shows a <1 Earth radius passage. If the HORIZONS ephemeris is right, the earliest this would be picked up is by a NEO survey in early 2024
astrosnapper
CC BY-SA 4.0
2023-05-01T13:28:52.997Z
https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2001%20VB has a solution date of 2021-Apr-14, but it's still only using the observation data from Nov 2001. But I guess Horizons may be able to give a more accurate trajectory using the improved precision in DE441.
PM 2Ring
<telescope><asteroids><near-earth-object>
2001 VB - when will it be reacquired?
Dragon
# 2001 VB - when will it be reacquired?

(Asked by: username_0 on 2021-06-22)

[2001 VB](https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=K01V00B)'s orbit is poorly known but has a two-in-a-billion risk of a collision with the earth in 2023.

Assuming that it **were** on a collision course, when would it be likely to be reacquired? Which telescopes would be most likely to do this? Would the likely reacquisition date change significantly if it is not on a collision course?

<https://cneos.jpl.nasa.gov/sentry/details.html#?des=2001%20VB>

<https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=2001%20VB>

**Tags:** telescope, asteroids, near-earth-object
> **Comments:**
> **username_1**: Something is weird and doesn't add up with this. The HORIZONS predictions for 2023 July have it over 3 AU away from the Earth and super faint but the close approach shows a <1 Earth radius passage. If the HORIZONS ephemeris is right, the earliest this would be picked up is by a NEO survey in early 2024  
> **username_2**: https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2001%20VB has a solution date of 2021-Apr-14, but it's still only using the observation data from Nov 2001. But I guess Horizons may be able to give a more accurate trajectory using the improved precision in DE441.  

---

## 2 answers

### Answer by username_4 on 2021-06-23. Score: 5 | Accepted answer

The remote chance of an Earth impact in late July 2023 may depend on hitting a small "keyhole" near Venus on 2002-01-09.
[NEODyS](https://newton.spacedys.com/neodys/index.php?pc=1.1.8&n=2001VB) gives an 8% chance that 2001 VB even passed within 0.1 au of Venus then.

Elsewhere in the cloud of possibilities are:

* a miss by 0.17 au in mid July 2023 ([MPC](https://minorplanetcenter.net/iau/MPEph/MPEph.html))
* a miss by 0.70 au in late April 2024 (HORIZONS)
* a miss by 0.49 au in late June 2024 ([NEODyS](https://newton.spacedys.com/neodys/index.php?pc=1.1.3.0&n=2001%20VB))

In any case, this object should be bright enough to recover 2 or 3 months before closest approach to Earth.
The major near-Earth asteroid [search programs](https://cneos.jpl.nasa.gov/about/search_program.html) currently detect objects at apparent magnitude 21 or 22.

> **Comments:**
> **username_5**: Cool answer! I'm just curious; is the 2002 pass of Venus actually being a proper keyhole for Earth impact in 2023 your view, or have orbital dynamics calculations been published showing this to be the case? ([Do all dangerous asteroids first pass through keyholes?](https://space.stackexchange.com/q/41550/12102) and answer(s) to  [Gravitational keyhole for spacecraft flyby?](https://space.stackexchange.com/q/37273/12102))  
> **username_4**: @uhoh That's my guess; I don't see a paper about it. Studies with [OrbFit](http://adams.dm.unipi.it/orbfit/) or [FindOrb](https://www.projectpluto.com/find_orb.htm) are an exercise for the highly motivated reader. :)  

---

### Answer by username_3 on 2023-05-01. Score: 2

According to [the Sentry Risk list](https://cneos.jpl.nasa.gov/sentry/details.html#?des=2001%20VB), it was removed in 2021. Must not be possible anymore.

> **Comments:**
> **username_2**: See https://cneos.jpl.nasa.gov/sentry/intro.html for info on how impact risk is determined, including the new algorithm which was introduced in 2021.  
> **username_0**: That was the overwhelming probability, thankfully :)  
> **username_0**: 22 July 2021, according to https://cneos.jpl.nasa.gov/sentry/removed.html .  So turns out my answer was "next month"...  

---

