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Questions tagged [entry-descent-landing]

Questions about the end-to-end process of landing a spacecraft on a target

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What is a "suicide burn"?

The term suicide burn occasionally comes up in answers and comments, usually without any real explanation or definition. What is meant by the term "suicide burn"?
user's user avatar
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13 votes
1 answer
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How does a gamma ray altimeter work? What kind of sensor is used?

The answers to the Space SE question Soyuz landing ground detection really surprised me. A gamma ray altimeter is used by the returning Soyuz capsule to detect the presence of solid ground immediately ...
uhoh's user avatar
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When things land on Mars what fraction of their velocity do they remove propulsively?

Some recent comments have got me wondering about this What is the distance between one of the mars's satellite revolving near the highest volcano olympus mons and the volcano olympus mons? comments ...
uhoh's user avatar
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Blimp on Earth, but a glider on Mars?

Could enough surface area be created with a blimp to shed speed using Mars' atmosphere to have a controlled soft landing to minimize the need for retrorockets? Runway would need to be in place. While ...
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7 votes
1 answer
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How could the landing date of Perseverance Rover be fixed irrespective of 26 days launch window?

I am very much aware of this question from 2018 by @uhoh - Why would InSight's arrival date at Mars be fixed, and independent of the launch date?. I was led here by a similar question which arose in ...
OrangeDurito's user avatar
10 votes
1 answer
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Can the space shuttle use OMS engines during landing?

Can the space shuttle use its OMS engines if the shuttle is short during the runway approach? Is fuel available for use in such a situation and will the engines provide reasonable thrust to get to the ...
Ashvin's user avatar
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7 votes
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Is Perseverance's heat shield's thickness radially symmetric?

I came across this video1 about the Mars 2020 Perseverance rover mission, especially the atmospheric entry phase. It says between about 03:50 and ...
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5 votes
1 answer
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Has there ever been an attempt or serious consideration for spacecraft to land on Mars without an ablative-type heat shield?

My answer to Do exploration spacecraft enter Mars atmosphere against Mars rotation, or on the same direction? lauds the use of ablative heat shields for minimizing radiative heating of a spacecraft by ...
uhoh's user avatar
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4 votes
1 answer
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When during the flights did astronauts use the Valsalva device?

A spongy material is installed to the inside helmets called the Valsalva device (top right in this image) allow astronauts to do the Valsalva maneuver to relieve pressure on their eardrums when there ...
Bob516's user avatar
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2 votes
5 answers
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Can a blimp dead drop on Mars or Earth this way?

I saw a space jump where someone had exceeded the speed of sound before the air slowed him down enough to deploy a parachute, because the air was not dense enough to tear him apart in the upper ...
Muze's user avatar
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2 votes
2 answers
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What were Mars 2's conical aerodynamic braking shield and "gunpowder" engines?

The Soviet Mars 2 and Mars 3 lander missions were the first (human-made) spacecraft to reach the surface of Mars with Mars 3 the first successful landing. They both carried Prop-M's; the first wheel-...
uhoh's user avatar
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How to retrieve MSL EDL trajectory using Javascript and webgeocalc API?

I found a "javascript gateway" to NASA SPICE data, the "webgeocalc" web api: https://wgc2.jpl.nasa.gov:8443/webgeocalc/example/perform-calculation.html It works both online and ...
jumpjack's user avatar
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-9 votes
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Can a reusable electric powered blimp stage for launch possible? [closed]

Originally this question asked about using blimps and electricity in replacement of boosters. As written then it was no good and got down votes. I had a few question marks and each question really ...
Muze's user avatar
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15 votes
3 answers
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What happens to Insight's parachute on Mars?

All of the animations I see show the heat shield detaching and falling to the ground, then Insight detaching and landing. There is no information about what happens with the upper part of the heat ...
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10 votes
2 answers
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Why does in-flight mission abort often ends in ballistic high-g reentry?

I am seeing a lot of references to the “ballistic reentry” mode of the crew return vehicle in relation to the abort during the powered ascent stage. In partiulat, the recent crewed Soyuz MS-10 abort ...
kkm mistrusts SE's user avatar
9 votes
1 answer
905 views

Why is InSight's nylon parachute a "soft good"?

NBC News' Mars InSight's landing team leader is all 'nerves and excitement' ahead of risky touchdown includes a conversation with Rob Grover, "who leads the team in charge of InSight's landing at ...
uhoh's user avatar
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8 votes
1 answer
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How different was the Apollo LM descent trajectory from the most fuel-efficient?

In most diagrams of the Apollo Lunar Module descent profile (example at the start of this video), it looks like the LM turns over and points some of its thrust downward relatively early in the process....
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8 votes
1 answer
359 views

Archimedean braking for low density Venus lander + subsidiary question

Subsidiary question: Imagine a sphere 10cm in diameter in low venusian orbit. Slow it down a little in order to deorbit it. What's the density of the sphere, in order to touch the ground at 0 vertical ...
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7 votes
1 answer
406 views

Can the SuperDraco engines aboard Crew Dragon be used to save the crew on splashdown if the chutes failed?

I've heard it several ways, so I should ask here. In the case of a main chute failure, are the SuperDracos able to attempt a contingency propulsive splashdown to save Dragon's crew? If this is in the ...
Anton Hengst's user avatar
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6 votes
2 answers
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Drawbacks and advantages of two slidable & rotatable control surfaces for BFS sized spaceships

BFS (SpaceX's Big Falcon Spaceship) is in development and has seen between 2016 and 2018 three major design modifications. January 2018 I asked here how BFS planned to manoever during aerobraking. ...
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6 votes
2 answers
220 views

How does a Mars lander reach a chosen landing site?

I see lots of questions how landing sites are chosen, but none so far how these landing sites are reached. It already looks like magic how the target planet can be reached at all, but when are ...
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1 answer
164 views

When NASA spacecraft arrive at Mars, is Mars always always above the horizon in the US?

Writing How long did the plasma blackouts of Perseverance's signals to MRO and direct-to-Earth last during its seven minutes of terror? I noticed that Mars was high in the sky over the Green Bank ...
uhoh's user avatar
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5 votes
1 answer
180 views

Are there any studies or technology envisioned for Mars entry and landing without a parachute?

Are any space agencies examining the possibility of a Mars landing without a parachute? It wasn't clear to me if the use of the HIAD (Hypersonic Inflatable Aerodynamic Decelerator) would eliminate ...
Bob516's user avatar
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4 votes
3 answers
1k views

How much time it takes for the capsules to descend from ISS back down to Earth?

How much time it takes for the space capsules to descend from ISS back down to Earth? Soyuz, Dragon, Crew Dragon, Cygnus, European ATV and Japanese HTV and any other such craft. From the moment they ...
Joe Jobs's user avatar
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3 votes
1 answer
468 views

How many spacecraft bounced like a ball on Mars? How many tried to?

The answer to Why a rover bounces after landing on Mars? is "the Mars Exploration Rovers" of which there were two. However, they might not be the only spacecraft to use bouncing like a ball ...
uhoh's user avatar
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3 votes
2 answers
337 views

Maximum dynamic pressure upon Mars entry

I have a Mars landing simulation, and one of the things it calculates is the dynamic pressure as the spacecraft descends through Mars' thin atmosphere (given by $q=\frac{1}{2}\rho v^{2}$). I know it ...
InquisitiveInquirer's user avatar
3 votes
2 answers
3k views

What is the return speed of the Falcon 9 booster?

The Falcon 9 first stage detaches at about 70 km high and it descends in about 6 minutes. That means an average descending speed of 200 m/s But what is the maximum speed it reaches on descent? And ...
Joe Jobs's user avatar
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3 votes
0 answers
95 views

Atmospheric entry of asteroid mining products

This is a more general question than How to get processed asteroid metals back to Earth in a safe manner That question was actually a quick check to see if a particular idea was plausible. Instead, ...
Craeft's user avatar
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1 answer
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Falcon 9 altitude and speed during reentry burn?

After MECO, stage 1 of Falcon 9 does up to three engine burns: a boostback burn followed by a reentry burn followed by a final landing burn. I'm interested here in the reentry burn. How high and how ...
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