25
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In deep space missions, how much of the journey is pre-programmed and how much is "direct" control?
The journey to the destination is about always completely pre-planned. All the gravity assists, close fly-bys, and so on, are planned before launch - and often long before the probe design is ...
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18
votes
Why are Europe’s Air & Space Academy and DLR urging ESA and CNES to reconsider the use of solid fuels for the proposed Ariane 6?
This is a pretty interesting question in retrospect now.
When it was asked in 2013, booster re-usablity was just a gleam in SpaceX's eye. The first Falcon 9 attempt to land a booster wasn't until ...
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18
votes
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JWST - image acquisition - what is a dither pattern?
Generally,
In astrophotography, to dither means to shift the pointing of the telescope slightly in random directions between exposures. This allows hot and cold pixels, cosmic ray artifacts, and ...
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14
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Is there any independent evaluation/report on the feasibility of SpaceX going to Mars by 2024?
I don't have any independent evaluations on hand but it is almost completely certain that SpaceX will not have any rockets landing on Mars in 2024 or leaving for Mars in 2024. Launch windows aren't ...
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14
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Were any other Space Shuttles ever planned?
I think Sagan was being optimistic. The original plan was for a large fleet of shuttles to support a very high mission flight rate, but according to Wikipedia, by 1983, the plan was to hold the fleet ...
- 167k
13
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Any potential downside to throwing personal life support out the door on the Moon?
They threw out the PLSS, but that didn't leave them without the use of those space suits entirely. The space suits could be coupled via umbilicals to the LEM ECLSS or to the CM life support system (...
- 126k
13
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Have there been any setbacks due to COVID-19-- like delays or data-loss?
Definitely. There's an article in Spektrum.de on it. It's in German, but it references some English-language articles. A referenced article (English) says that launches at the Guiana Space Center (...
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10
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How would a Jupiter flyby have helped to get to the Sun? Why was it later ruled out?
A gravity assist at Jupiter would have been used to decrease Solar Probe (Plus)'s orbital speed, lowering its perihelion as explained well in this answer.
Credit: NASA/JHUAPL
In fact, for such an ...
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9
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What was back-up plan in case of Apollo CSM Primary Guidance System IMU went to gimbal lock?
The Apollo attitude control system starts from a known orientation established by taking star sightings, then uses gyroscopes to track the change in orientation over time. The problem with gimbal lock ...
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9
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Before the Columbia accident, were there shuttle manifests/plans for after ISS assembly complete?
In case anyone else is curious, I did find some information on this, in a document dated Jan 29, 2003, three days before the Columbia accident. It shows projected flights going out to STS-147 in late ...
- 178k
8
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Before the Columbia accident, were there shuttle manifests/plans for after ISS assembly complete?
Not that I recall ever seeing!
This is a copy of the 2001 Consolidated Launch Manifest, which only goes out to 2006; it has two non-ISS flights, STS-107 and the fourth Hubble flight.
This list isn't ...
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6
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Have there been any setbacks due to COVID-19-- like delays or data-loss?
Let the bad times roll! :-(
NPR reports that the Russian-European ExoMars mission to Mars has been delayed. While factors other than COVID-19 figured into this decision, there was also this ...
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6
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Where is Lucy going? (asteroid mission)
A more detailed trajectory is available in the usual place for the sort of detail you're looking for: the NTRS.
LUCY: NAVIGATING A JUPITER TROJAN TOUR
A unique trajectory was discovered which visits ...
- 126k
6
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Why didn't NASA re-use more astronaut crew members?
I'm writing this answer as a community wiki. The reasons are manyfold; feel free to add more.
@Digger notes that NASA requires Commanders to have previous experience in space. It is therefore ...
5
votes
How fast can a launcher be retargeted?
It depends, on how much testing you want to do, etc. Each launch has a specified vibration testing that is done to ensure that there won't be any problems. Swapping out a payload, depending on the ...
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5
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How (the heck) can 2014 MU69's orbit be know well enough for a close flyby by New Horizons?
Okay, collecting my comments into an answer:
As soon as you have a visual, and have enough delta-V, you CAN get a fly-by, although precise time and speed of flyby will remain unknown until much ...
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5
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How (the heck) can 2014 MU69's orbit be know well enough for a close flyby by New Horizons?
The long orbital calculations of Pluto's orbit were done primarily to save fuel, and secondarily to target a very narrow region. The mission intended to fly between the Sun and Pluto and Charon (And ...
- 121k
5
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How fast are trips to the Moon for unmanned spacecraft typically?
Are most trips to the Moon actually around 3 or 4 days, and not the 5.0 days of a half-ellipse?
The 5 spacecraft of the US Lunar Orbiter program took 3.8-3.9 days to reach lunar orbit.
The Ranger ...
- 167k
5
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How did NASA decide on its missions?
It depends on the type of mission. Generally:
Scientific missions these days are decided on via the decadal surveys (for astronomy, planetary science and earth science). These are organized by the ...
- 126k
5
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Has space weather ever impacted spacecraft launch schedules?
In 2014 a solar flare delayed the launch of a private cargo delivery to the International Space Station by 24 hours due to concerns over space radiation.
The event occurred as the commercial ...
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4
votes
Assuming MLM/Nauka is launched, what happens to MRM-1/Rassvet?
Actually, the idea of MLM being docked to the bottom of Zarya FGB was a thing in the years 2004-2007. At that time MRM-1 Rassvet and MRM-2 Poisk didn't exist, and DC-1 Pirs was supposed to move to the ...
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Assuming MLM/Nauka is launched, what happens to MRM-1/Rassvet?
The MLM is replacing the DC-1 docking compartment (Pirs). Not Rassvet. It is docking to Zvezda not Zarya.
Russian Space Web has an excellent article on the history of the MLM/Nauka/FGB-II module. ...
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4
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How would a Jupiter flyby have helped to get to the Sun? Why was it later ruled out?
The Jupiter flyby mission concepts were nuclear-powered. They were told to come up with a non-nuclear option.
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4
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Were there contemporary criticisms of NASA's pre-Challenger plans to exclusively use the Shuttle for US launches?
According to The Space Shuttle Decision, the White House Office of Management & Budget, at the end of 1971, had concerns:
Similarly, the OMB would not permit its shuttle to be all things to ...
- 167k
3
votes
If something "falls off" the L2 or L1 point, where will it go?
...when a spacecraft stationed there diverges toward either side of the saddle, and station-keeping is no longer maintained, where will it go?
The Earth-Sun $L_{1}$ point is unstable, just like the ...
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3
votes
Why is NASA redirecting an asteroid to Lunar Orbit instead of LEO?
The reason is that a lunar orbit (specifically, a distant retrograde orbit or DRO) is much more stable compared to a low Earth orbit so you can leave it there for a long time and study it in the ...
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3
votes
Where can I find detailed information on spacewalks?
Most of the publicly available procedural information you seek is on the Johnson Space Center Flight Data File page.
It may help to briefly review the organization of the EVA checklist documentation.
...
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3
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What are the limiting factors for interplanetary mission trajectories?
There's plenty of additional constraints on interplanetary trajectories. Of course the ones you mentioned first are the most driving constraints.
Concerning the others you mentioned maximum number ...
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3
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How well can the orbits of Jupiter Trojans to be visited by Lucy be predicted?
In this answer to the question How to calculate the planets and moons beyond Newtons's gravitational force? I show that you can calculate the Sun, the Moon, the planets and several asteroids to one ...
- 148k
3
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Why does ExoMars have more landing ellipse flexibility in 2020 than in 2018?
My answer is based on the article: "Selecting a Landing Site for the ExoMars 2018 Mission".
Vago, J.L., Lorenzoni, L., Calantropio, F. et al. Sol Syst Res (2015) 49: 538. https://doi.org/10.1134/...
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Only top scored, non community-wiki answers of a minimum length are eligible