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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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35 votes
3 answers
6k views

Why was it necessary to program InSight with an ability to land in dust storms?

If the entire event of EDL (Entry - Descent - Landing) is going to take only 7 minutes and if the command to begin could be signalled based on ground weather conditions, why was it necessary to take ...
karthikeyan's user avatar
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28 votes
7 answers
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Curiosity and Perseverance landing - with so much dust blown everywhere, what's the point of the skycrane?

Curiosity and Perseverance were landed using the rather complex skycrane system because it would prevent the rockets from contaminating the landing site. But the video shows a great deal of dust being ...
ikrase's user avatar
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27 votes
3 answers
6k views

Why won't NASA show any computer screens?

This question was inspired by yesterday's NASA video stream of Perseverance landing on Mars (congratulations). I like watching rocket launches, they are really awe-inspiring, even if it's just a SN9 ...
Edheldil's user avatar
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18 votes
4 answers
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Is there a risk that re-entering capsules or other components will hit ships or islands?

How precisely can the splash-down point of re-entering capsules (from Mercury onwards) be known in advance? Wasn't there a risk that capsules would hit a ship or an island? Likewise, Russian and ...
Joshua Fox's user avatar
18 votes
1 answer
3k views

How did NASA avoid a repeat of the Mars Polar Lander failure?

One of the most likely causes of the MPL (Mars Polar Lander) crash landing on Mars was the deployment of the legs being mistaken by the onboard computer as touchdown. Phoenix (and later InSight) ...
Andykins 's user avatar
15 votes
3 answers
2k views

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 ...
anonymous'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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13 votes
1 answer
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Why are cone shaped heat shields used for Mars entry?

Heat shields used for Earth reentry are usually curved but heat shields used for Mars’ entry are coned shaped. Why is this?
Tom's user avatar
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12 votes
2 answers
1k views

Quickest return from stable Earth orbit to ground?

Inspired by this Worldbuilding question about orbital deployment (deploying things to the ground from orbit): What is the quickest that something has actually deorbited and landed from a stable closed ...
kwc's user avatar
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10 votes
1 answer
932 views

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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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
10 votes
1 answer
7k views

What is crossrange and downrange for an entry vehicle?

I have been searching the terms online but still can't get a more intuitive understanding. If you could refer me to some website, book or if you could offer me an explanation I would really appreciate ...
dareToDiffer07's user avatar
10 votes
1 answer
783 views

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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10 votes
1 answer
304 views

What went wrong in the Chandrayaan-2 mission with the Vikram lander?

On September 7th 2019, ISRO attempted to land a lunar lander ,Vikram, with rover , Pragyan, on the moon. It was very exciting to watch until the lander lost communication with ground station during ...
John's user avatar
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9 votes
4 answers
4k views

Why don't SpaceX boosters belly flop?

The first F9 booster landing attempts failed because the booster broke up. After that, they began lighting the engines in the upper atmosphere to slow the booster. It seems to me that their problem ...
Abdullah is not an Amalekite'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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9 votes
3 answers
456 views

Would this Starship design alternative be viable?

Considering Starship's atmospheric entry, belly dive and "bellyflop", latest iteration displays four aerodynamic surfaces, two aft fins and two canard fins. Soon, this configuration will be ...
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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 ...
user avatar
8 votes
1 answer
647 views

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....
Nick S's user avatar
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8 votes
1 answer
573 views

Meteor color hints at chemistry

This recent meteor over the midwest. Reports described it at blue / green. I have seen blue / white, red and yellow meteors. I presume red means iron, green means copper. Can meteoritics or meteor ...
Johnny Robinson's user avatar
8 votes
2 answers
316 views

Falcon 9: Why does F9 first stage always lose Video Link during Entry Burn?

Typically the F9 first stage and the drone ship each lose the video connection once during landing: F9 first stage during entry burn Drone ship during F9 first stage touch down (see here and here) ...
Dave's user avatar
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7 votes
1 answer
725 views

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
7 votes
1 answer
407 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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7 votes
0 answers
59 views

Why wasn't the MSL landing ellipse in Gale Crater placed further South?

This paper documents the final landing site selection process for the Mars Science Laboratory (MSL) mission. One of the cons associated with Gale Crater (as pointed out in Table 10 of the paper), was ...
olamarre's user avatar
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7 votes
0 answers
72 views

What are the rules for callouts during mission landings?

I remember hearing at one point that in the control room at JPL, only the GN&C Lead is allowed to make the announcement for touchdown. It's because they don't want someone prematurely (and ...
Phiteros's user avatar
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7 votes
0 answers
261 views

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 ...
user avatar
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 ...
nmajoros's user avatar
  • 327
6 votes
3 answers
302 views

Where can I find high quality "descent" photos at as many different altitudes as possible?

I'm working on a graphical simulation and I'd like to get the "look and feel" to seem as realistic as possible. Other than Apollo landing videos (which seem pretty limited and low quality obviously) ...
User's user avatar
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6 votes
1 answer
308 views

With and without refilling at LEO, how much more than the landers weight of the Venera 9 mission could a Starship deliver near a pole of Venus?

Venera 9 was a Soviet space mission to Venus that consisted of an orbiter and lander with a launch mass of 4936 kg and with an entry mass of 1560 kg. It was the first spacecraft to return an image ...
Cornelis's user avatar
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6 votes
1 answer
198 views

Starship surface heating on Mars landing

Mars atmosphere is much thiner than Earth's And then how much will Starship heat on a Mars landing comparing to a landing on Earth?
Joe Jobs's user avatar
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6 votes
1 answer
401 views

Did the manned NASA capsules rotate during descent?

Watching the NS-11 launch, I noticed that during descent when the main chutes were deployed, the capsule rotated quite a bit, and would rotate back. Was this an issue as well during the Mercury/...
CBredlow's user avatar
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6 votes
2 answers
368 views

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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5 votes
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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5 votes
2 answers
351 views

Is there a way to recover any of the energy of reentry of a Mars lander?

Is there a way to recover any of the energy of reentry of a Mars lander? Tremendous energy is generated as a craft enters the atmosphere – admittedly over a fairly short time - and only one time. We ...
A. Flowers's user avatar
5 votes
1 answer
284 views

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
  • 149k
5 votes
0 answers
251 views

Lunar Descent and Landing Simulation

I am trying to simulate lunar descent and landing as a part of my undergraduate project. For time being, I have included gravity turn guidance scheme and used these equations Now, I can solve ...
Kuldeep Barad's user avatar
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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4 votes
2 answers
1k views

Can we significantly reduce entry velocity with this method by airbraking alone for interplanetary travel?

For example, can a space ship overshoot Mars in a reverse gravitational slingshot mixed with a little air breaking, steering to keep the spacecraft from orbit and then land on Mars with a near 0 ...
Muze's user avatar
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4 votes
1 answer
280 views

How long does the descent of the Falcon 9 first stage take?

After separating from the second stage, how long does it take for the Falcon 9 to come back to Earth? From LEO and from GEO. Note: this question is similar: How long does it take to recover the first ...
Joe Jobs's user avatar
  • 2,650
4 votes
1 answer
190 views

Why Crew Dragon needs 18 hours between ISS separation and descent?

The Crew Dragon undocks from ISS but then it spend 18 hours in orbit before deorbit burn. From there, it takes less than one hour to come back to Earth. Why it needs 18 hours? Evven if they check all ...
Joe Jobs's user avatar
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4 votes
2 answers
531 views

How was an emergency landing site at Diego Garcia used during the Apollo program?

On the current Starlink mission as the 2nd stage passed over the Indian Ocean I heard mention of contact with a ground station at Diego Garcia. Checking that article I found the subsection Space ...
uhoh's user avatar
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4 votes
1 answer
585 views

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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4 votes
1 answer
283 views

How to get MARS2020/Perseverance EDL trajectory data from spice kernels?

For MSL EDL it is available this answer: How to retrieve MSL EDL trajectory using Javascript and webgeocalc API? How can I adapt it to MARS2020/Perseverance?
jumpjack's user avatar
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4 votes
2 answers
282 views

How did "STOP" button work on Lunar Module?

The button to stop the descent engine of Lunar Module was not "just a button": it evolved and changed multiple times during development, and this is one of the many existing designs: What ...
jumpjack's user avatar
  • 3,043
4 votes
0 answers
197 views

Atmospheric Entry Simulation: Numerical Inaccuracy

I am trying to make an atmospheric entry/aero-assist simulation. For the propagator, I have used conventional equations of motions in planet fixed reference frame: where the scalar states are- ...
Kuldeep Barad's user avatar
3 votes
1 answer
1k views

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 ...
Muze's user avatar
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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
  • 2,650
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