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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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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 ...
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 ...
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 ...
1 vote
0 answers
98 views

How to approximate the force generated by Falcon 9 grid fins?

I'm interested in approximating the force generated by the grid fins on a Falcon 9 rocket during its descent phase. However, I currently lack specific data and equations for this calculation. Can ...
0 votes
0 answers
90 views

How do you approximately calculate the center of pressure during flight? [duplicate]

I'm working on a simulator for landing the falcon 9 booster rocket. I'm aiming to incorporate aspects like the effects of restorative torque. However, I've been trying to figure out how to determine ...
0 votes
0 answers
139 views

How to Model the Aerodynamics of Landing a Falcon 9

I'm currently working on a landing simulation for the Falcon 9. One of my primary tasks is to model both the environment and the rocket. In a previous rough simulation, aerodynamics were mostly ...
0 votes
2 answers
360 views

How can Starship belly flop with a full payload?

Starship had an empty weight of under 100 tons. Of this, less than 12 tons is accounted for by the engines. Starship is supposed to be able to make atmospheric entry with a 150 ton payload in the nose....
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 ...
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) ...
2 votes
0 answers
108 views

Is it possible for fuselages to have a negative lift coefficient at positive angle of attacks?

Recently I was interested in the descent phase of the first stage of the falcon 9 launch vehicle. I assumed a long cylinder to represent the first stage. using DATCOM to predict aerodynamics ...
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 ...
13 votes
1 answer
488 views

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?
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?
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 ...
-3 votes
1 answer
285 views

Can starship land back on earth after sending 100 tons to LEO? [closed]

Starship payload capacity to LEO is shown as 100 metric tons in SpaceX's Page. Can the starship land after sending this payload or will it require orbital refuelling to return to earth? Related but ...
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 ...
1 vote
0 answers
223 views

Defining overshoot and undershoot boundary of entry corridor

I have been reading up on the mathematic of atmospheric entry. I have found different methods to theoretically calculate the corridor width but I don't understand how to define the overshoot and ...
3 votes
1 answer
168 views

How is parachute cover during Mars EDL prevented from crashing onto parachute or lander upon parachute opening?

MARS2020/Perseverance footage of parachute opening shows that parachute cover ejected by the lander (together with other "things") followed same trajectory of parachute box, until parachute ...
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 ...
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?
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 ...
2 votes
0 answers
218 views

Apparent close encounter of Inspiration4: Is the airspace cleared for returning spacecraft?

In the recording of the SpaceX live-stream covering the return of the Inspiration4 crew one can see an aircraft cross path with the capsule at 22:59:58. This image is a frame grab of the scene seen ...
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) ...
2 votes
1 answer
193 views

From what altitude will they cut Dragonfly helicopter loose on Titan and make it land itself, and what are the main factors determining this altitude?

Titan's surface pressure is about 1.5 bar and because the surface gravity is low pressure falls off much more slowly with altitude than it does on Earth. From Wikipedia's Atmosphere of Titan; vertical ...
3 votes
0 answers
178 views

Why does the landing trajectory of a blunt body take an S shape in the lower atmosphere?

I coded some Matlab plots of altitude vs time for the re-entry of a point mass (so no aerothermo analysis included). In all the trajectories, there is an S shape closer to the ground. Why? Please ...
28 votes
7 answers
6k views

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 ...
3 votes
1 answer
469 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 ...
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 ...
2 votes
2 answers
190 views

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-...
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 ...
2 votes
1 answer
160 views

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 ...
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 ...
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 ...
3 votes
0 answers
122 views

How to get MSL coordinates during EDL from SPICE kernel?

Upon trying to extract MSL position above surface by decoding a SPICE kernel, I am gettin this error: At epoch 3.9750216818313E+08 TDB (2012 AUG 06 05:16:08.183 TDB), there is insufficient ...
0 votes
0 answers
80 views

How long to flip over stage 1 of Falcon 9?

Curious how fast stage 1 flips over. 180 degrees is a lot of turning. At a rate of 5 deg/s, it would take 36 seconds to flip. This seems very long for the maneuver. A more modest duration of 10 s ...
0 votes
1 answer
2k views

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 ...
2 votes
1 answer
210 views

How long do the ascent and the descent of Virgin Galactic's spacecraft take?

The VMS Eve mothership releases the VSS Unity spacecraft after ca. 48 minutes. The total duration is approximately 2 hours. As a result, the ascent time + the descent time that the Virgin Galactic's ...
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 ...
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 ...
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 ...
18 votes
4 answers
3k views

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 ...
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 ...
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 ...
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 ...
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 ...
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, ...
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 ...
0 votes
0 answers
165 views

Why have JPL martian rovers stopped using airbags and started using skycranes? [duplicate]

Pathfinder and the Mars Exploration Rovers used airbags to kill their terminal velocity. The Curiosity and Mars 2020 rovers have or will use skycranes. Why have JPL started using propulsive terminal ...
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 ...
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 ...