51 votes
Accepted

Why isn't a centrifuge used for astronauts on the space station?

The short answer is it would cost a lot of money. In order to get a 1G force, you'd either need something really big, or rotating very fast. For example, the reference design for the space colonies ...
FKEinternet's user avatar
  • 1,756
50 votes

What is "mission design"? What do mission designers do (if such a designation exists)?

Yes, there are people whose sole job is "mission design." They design the trajectory that a spacecraft should follow to fulfill its mission and all of the maneuvers needed for that to happen....
ChrisR's user avatar
  • 6,220
38 votes
Accepted

Exactly why does Starship need to be this big for interplanetary travel?

A lot of launch costs are independent of rocket size. It's no cheaper to clear the flight path for a smaller rocket, for example. It also takes a lot longer to do 10 launches instead of one large ...
Christopher James Huff's user avatar
36 votes

Why did the space shuttle's altitude go down after reaching 108,000m?

The drop in acceleration around 40s into the flight is the shuttle throttling down to reduce the aerodynamic load on the vehicle. It then accelerates when past this point. The drop in acceleration at ...
Innovine's user avatar
  • 4,625
36 votes

Why doesn't JWST use ion thrusters?

Since the L2 point is unstable, JWST needs engines to maintain it's orbit. It uses mono-propellant engines which have given it a 10 year (maximum) lifespan. The JWST uses bi-propellant engines (...
David Hammen's user avatar
  • 74.8k
34 votes

Would it have been any more difficult to build the space station without the space shuttle?

I do not think your assertion that "other rockets were just as capable of performing the task at that time" is correct at all. I'd love to hear your counterexamples, if you have any. Perhaps you are ...
Organic Marble's user avatar
32 votes

Would it have been any more difficult to build the space station without the space shuttle?

Launching and assembling the ISS in its current design could not have been accomplished without the STS (Shuttle system), but that is largely because the ISS was designed with the STS in mind as its ...
Kengineer's user avatar
  • 1,748
31 votes

How realistic is the 1 kg/km² solar sail in "Death's End"?

A solar sail with an areal density of $1~\mathrm{kg}/\mathrm{km}^2 = 1~\mathrm{mg}/\mathrm{m}^2 =0.001~\mathrm{g}/\mathrm{m}^2$ is impossible by known materials science because graphene has an areal ...
WaterMolecule's user avatar
29 votes
Accepted

Why weren't Saturn V and the Soviet N-1 Moon rockets made larger in order to simplify Lunar missions?

In order to use the direct ascent method of landing on the moon, which is where the entire vehicle descends and leaves the moon, you would need a rocket an order of magnitude bigger than the Saturn V, ...
GdD's user avatar
  • 20.3k
29 votes
Accepted

Is this plot of deep space trajectories correct? Did most launch retrograde from Earth? Why do some change direction between planets?

The diagram you show is the digital version of a drawing by someone with an Etch-a-Sketch: completely inaccurate. The diagram below is accurate, showing Pioneer 10 & 11 and Voyager 1 & 2 ...
Tom Spilker's user avatar
  • 18.3k
28 votes

How will DART be able to hit a 170 meter rock dead-center at over 6000 m/s? What technologies will be use and how will they work together?

Didymos will be roughly 11 million kilometers (6.8 million miles) from Earth at the time of the DART impact.The round trip time for a radio signal from DART to the control center on Earth will be ...
Uwe's user avatar
  • 49k
26 votes

How much did we know about lunar soil conditions prior to Apollo 11?

The uncrewed Surveyor probes landed on the moon before Apollo did. They provided visual images of the landscape and pictures of soil samples that were dug up robotically. All the visual indications ...
Russell Borogove's user avatar
26 votes

How hard is it to fly through the tail of a comet? Has it been done?

Ulysses, the shuttle-launched joint NASA/ESA probe to study the sun's polar regions, ran through three comet tails, more or less by chance. Ulysses Catches Record for Catching Comets by Their Tails ....
Organic Marble's user avatar
26 votes

Is there something inherently more difficult about servicing satellites in the 2nd Sun-Earth Lagrangian point?

Distance certainly is a key factor. It took JWST a month to go from launch to L2 pseudo-orbit insertion. Another key factor is that to date, the only successful satellite servicing missions have been ...
David Hammen's user avatar
  • 74.8k
24 votes

What typically gets sent to the ISS?

If you want an example manifest for one logistics flight, that's available. Search terms...suggest "ISS Cargo Manifest" From SpaceX 2 Cargo Manifest (see link for details) 81 kg of crew ...
Organic Marble's user avatar
23 votes

Why doesn't JWST use ion thrusters?

@DavidHammen's answer goes a long way towards answering, especially in that the space telescope's bus was finalized quite a long time ago when ion propulsion was much less a proven long-term reliable ...
uhoh's user avatar
  • 149k
22 votes

Why weren't Saturn V and the Soviet N-1 Moon rockets made larger in order to simplify Lunar missions?

During the early part of the Apollo program, the "direct ascent" mode was favored and Lunar-orbit rendezvous (LOR) was considered far too complex. In fact, the specifications of the Apollo service ...
Russell Borogove's user avatar
22 votes
Accepted

Were the consoles in mission control computers or terminals for displaying information?

Since you have tagged the question apollo-program, I will explain the Apollo era consoles. Sources are from this Ars Technica article, which interviewed flight controller Sy Liebergot. The flight ...
DrSheldon's user avatar
  • 47.9k
21 votes
Accepted

How an americium-241 RTG would differ from one using plutonium-238?

Power and Mass From this paper (emphasis mine): The specific power of an 241Am-fuelled RTG cannot match that of a 238Pu system (except perhaps at small power output levels); however, the design work ...
Jack's user avatar
  • 9,976
21 votes

How well would Max Faget's April 1, 1969 design for the Space Shuttle have actually worked? What would have been the major problems?

The straight wing concept was perfectly workable. According to The Space Shuttle Decision, Max Faget preferred the straight wing approach primarily because it would optimize performance in the final ...
Russell Borogove's user avatar
20 votes

Has a spacecraft ever docked with the same space station twice in one mission?

The first, experimental redocking was performed on Soyuz 29 (though by crew of Soyuz 31) with the Salyut 6 station. Afterwards, the maneuver was repeated several times, usually between different ...
SF.'s user avatar
  • 55k
20 votes
Accepted

What target is the most difficult to reach in the solar system?

A couple of decades is long enough to reach more or less anywhere in the solar system by launching onto a Venus transfer and then using two or three Venus and Earth gravity assists to get to Jupiter ...
Steve Linton's user avatar
  • 19.6k
20 votes
Accepted

Are launch windows to Mars avoided if they result in landings during dust storm season?

Are launch windows to Mars avoided if they result in landings during dust storm season? No. It's pretty well known that the gusts of wind on Mars are relatively harmless to a person standing on Mars (...
Star Man's user avatar
  • 5,918
20 votes

How realistic is the 1 kg/km² solar sail in "Death's End"?

There is a extensive summary report on possible improvements of solar sail materials: "Ultra-Thin Solar Sails for Interstellar Travel - Phase I Final Report" December 1999, Dean Spieth, Dr. ...
asdfex's user avatar
  • 15k
20 votes

Is there something inherently more difficult about servicing satellites in the 2nd Sun-Earth Lagrangian point?

Getting to L2 in a timely fashion is more challenging than going to the Moon. The Apollo missions took about 3 days to get to the Moon. 4.5 days is how long the LRO took to orbit the Moon when ...
PearsonArtPhoto's user avatar
  • 121k
18 votes

How well would Max Faget's April 1, 1969 design for the Space Shuttle have actually worked? What would have been the major problems?

Mission Requirements for a spaceplane that are affected by its aerodynamic shape Cross-range capability Gliding range perpendicular to orbital plane on reentry. Otherwise, you have to wait in orbit ...
CourageousPotato's user avatar
18 votes
Accepted

Which 3D space simulation/visualization software (free or commercial) can I use as a post processor of data calculated with Fortran?

One option is SPICE-Enhanced Cosmographia. You could convert your output text files to SPICE SPK (.bsp extension) kernels or more simply a text file with structured data (see the InterpolatedStates ...
Alfonso Gonzalez's user avatar
17 votes
Accepted

When things land on Mars what fraction of their velocity do they remove propulsively?

Taking Mars Pathfinder and Viking 1 as examples: Mars Pathfinder was a direct entry at 7600 m/s and removed about 0.7-0.8% of that propulsively. Parachute deployment was at 360-450 m/s, and landing ...
Christopher James Huff's user avatar
17 votes
Accepted

Did the Apollo Command module really "skip" within, or off of the atmosphere as a part of its reentry program?

Text quoted here is from a presentation by John Burton called Introduction to Apollo Entry Guidance and Flight Performance Sorry about the giant block quote but it all seems relevant. Emphasis mine. ...
Organic Marble's user avatar
17 votes
Accepted

Can double deck spacecraft be designed and constructed for manned missions?

Yes. They can be designed. Big Gemini was a seven-person capsule design that took a two-seat Gemini capsule: (Note: this image shows both the capsule (the black part) and the service module (the ...
Anton Hengst's user avatar
  • 10.7k

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