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47 votes
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What eliminates the velocity when occupants return from ISS to earth, and how much?

Nearly all the velocity is cancelled by atmospheric deceleration of the descent module, before its parachutes are deployed. ISS orbital velocity is around 7700 m/s. An initial retro-burn of the ...
Russell Borogove's user avatar
28 votes
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Do exploration spacecraft enter Mars atmosphere against Mars rotation, or on the same direction?

There is always a benefit to entering a planet's atmosphere with matching rotation. In the case of Earth, the difference is a rather huge 920m/s effective airspeed between reentering prograde or ...
CuteKItty_pleaseStopBArking's user avatar
25 votes

What eliminates the velocity when occupants return from ISS to earth, and how much?

The process is described here, which answers nearly all of your question. The reentry burn removes about 120 m/s of velocity from the capsule (that's your 1) and the final impact is 15 miles per hour ...
Steve Linton's user avatar
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24 votes
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Bounce off the atmosphere at reentry?

Yes, a capsule cannot literally bounce off the atmosphere and its kinetic energy must be reduced by an encounter with the atmosphere, rather it would just pass through the atmosphere and back into ...
Blake Walsh's user avatar
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18 votes
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Can a reentry be done slowly?

Not without propellant. Or at least not easily. However the "why" is a bit tricky. This is far from the whole story but one of the problems is that generating enough lift to keep you from diving too ...
ANone's user avatar
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17 votes
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Would it be feasible to decelerate a crewed vehicle from ~25 km/s only using the atmosphere of Mars (in the context of an "express transit")?

Nope, sorry. Completely disregarding the (enormous) heat factor of the aerobraking. The requirement specifies manned. The path through Mars' atmosphere will be very nearly a straight line. A bit of ...
CuteKItty_pleaseStopBArking's user avatar
16 votes

How do we control a Reentering Capsule in the denser part of the atmosphere?

The entry vehicle for the Apollo missions is the command module (CM), which has a symmetric body with an offset center of gravity (c.g.). This offset c.g. causes the CM to trim ...
Organic Marble's user avatar
14 votes

How do we control a Reentering Capsule in the denser part of the atmosphere?

For Gemini, Apollo, and Soyuz capsules, lift is achieved by offsetting the center of gravity of the reentry module from the center line of the craft. This is represented in your diagram by the "...
Russell Borogove's user avatar
13 votes

How can delta-v and aerobraking as shown in this chart be explained?

Here's the original source of the diagram: https://www.reddit.com/r/space/comments/29cxi6/i_made_a_deltav_subway_map_of_the_solar_system/ Your concerns are also discussed there. 27000m/s is a very ...
Rikki-Tikki-Tavi's user avatar
12 votes

Can a reentry be done slowly?

It is possible to do a slow and cool reentry. But it would be extreamly expensive. Just slow down from orbit speed to subsonic speed above the atmosphere and then fight gravity until it is possible ...
Uwe's user avatar
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10 votes

How can delta-v and aerobraking as shown in this chart be explained?

The calculations for Ulysse Carion's chart were done by Curious Metaphor. If you go the this Reddit thread, you'll see a conversation between Curious Metaphor and I. For years I made delta V charts ...
HopDavid's user avatar
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10 votes
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Mathematically, what is the argument in favor of skipping reentries?

The two systems that I know of that were qualified for skip entry, Apollo and Shuttle, did so purely for cross-range capability. The skip entry would have been used for an emergency return that could ...
Mark Adler's user avatar
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9 votes
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Could a reentry powered monorail and flywheel make a kinetic engine for lift?

Take the super-optimistic 500 kJ/kg energy density of flywheel energy storage. In reality 10% of that would be a great result. $ E_k = {1 \over 2} mv^2$ so 0.5*1kg*(8km/s)^2 = 32MJ per kilogram of ...
SF.'s user avatar
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9 votes

Do exploration spacecraft enter Mars atmosphere against Mars rotation, or on the same direction?

Space craft will tend to enter orbit counter clockwise as viewed from the northern hemisphere. This is due to the fact that most objects in the solar system orbit and rotate this way with the ...
Slarty's user avatar
  • 9,720
8 votes

Gliding into the atmosphere

You can't just slow it down over many orbits I think the question is suggesting letting a little bit of drag slow the Cessna down until it's at a normal speed before gliding through the atmosphere. ...
Phil H's user avatar
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7 votes

What will Max Q for descent be?

According to https://www.flightclub.io/results/?code=SS10 , reentry Q for flights like SES-10 peak at almost 92kPa at T+434 sec, about 3x the ascent max Q. The reentry prep burn brings velocity down ...
Russell Borogove's user avatar
7 votes

Gliding into the atmosphere

First of all, the heat shields aren't there just for the dense atmosphere with high deceleration, the upper atmosphere part of reentry also generates heat. If you had a craft that could fly in the ...
JanKanis's user avatar
  • 541
7 votes

How can delta-v and aerobraking as shown in this chart be explained?

A 250km periapsis Earth orbit won't produce significant atmospheric drag. The inbound-aerobraking-possible notations for orbits are assuming that you dip lower into the atmosphere in order to slow ...
Russell Borogove's user avatar
7 votes

How can delta-v and aerobraking as shown in this chart be explained?

Adding to @Rikki-Tikki-Tavi answer. For destinations where aerobraking is possible, and you have a sufficiently heat and acceleration hardened vehicle, it's possible to cheat. The map shows how much ...
Leliel's user avatar
  • 168
7 votes
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Starship reentry velocity on return from Mars: What are the options

Starship's limited $\Delta V$ means that it can't stray too far from minimum energy transfers. 100t payload + 120t dry mass + 1200t of propellant + 380s $I_{sp}$ $\to$ ~$6900m/s$, turns out this wasn'...
BrendanLuke15's user avatar
7 votes
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Starting refueled in LEO, how much payload could a heat-protected Starship softly land on Mercury after a gravity assist from Venus?

A single Venus flyby helps, but it does not make the journey possible for Starship. Below is a plot of 2025-2030 trajectories from Earth to Mercury that flyby Venus once. They are plotted by the Earth ...
BrendanLuke15's user avatar
6 votes
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Is this a first Mars aerobraking for ESA, or for anyone?

ESA has done aerobraking with Venus Express. NASA has done aerobraking at Mars several times, as well as at Venus. This will be the first time that ESA has done aerobraking at Mars.
Mark Adler's user avatar
  • 58.2k
6 votes

Do exploration spacecraft enter Mars atmosphere against Mars rotation, or on the same direction?

See also answers to How much does the rotation of the Earth affect re-entry and could we go against it? When things land on Mars what fraction of their velocity do they remove propulsively? ...
uhoh's user avatar
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6 votes
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How did Venus Express' periapsis decay so quickly?

Venus Express (VEX) used a highly elliptical, polar orbit. A peculiar feature of this orbit around Venus is that the pericentre altitude will drift due to third body perturbations from the Sun's ...
Armadillo's user avatar
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5 votes
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How will BFS maneuver during aerobraking?

According to Elon, mainly with aerodynamic control surfaces. Compared to the design I showed last time, you can see that there’s a small delta wing at the back of the rocket. The reason for that is ...
Saiboogu's user avatar
  • 6,417
5 votes

In what atmospheric densities or pressures have aerobrakings been performed?

No spacecraft has yet used aerobraking for orbital insertion. That's called aerocapture. Aerobraking has been used by orbiters only after a propulsive orbital insertion. What matters for the drag of ...
Mark Adler's user avatar
  • 58.2k
5 votes

Orbital reentry glider with no heat shield

If you want to minimize heating, you need to spend time at high altitudes (>100 km) gradually losing speed. This means you need wings to provide lift. So for now I'm going to ignore the heating issue ...
Hobbes's user avatar
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5 votes
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Is aerobraking used for orbit insertion for each planet with an atmosphere?

You are confusing aerobraking with aerocapture. Aerobraking is used to circularize an elliptical orbit into a circular one after orbit insertion, and it has been used a few times on the following ...
GdD's user avatar
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5 votes

Starting refueled in LEO, how much payload could a heat-protected Starship softly land on Mercury after a gravity assist from Venus?

One thing to keep in mind is the trade off between use of gravity assists, the alignment of the planets at launch and the mission duration. It is theoretically possible to use multiple passes of the ...
Slarty's user avatar
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