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156 votes

If the astronauts on Apollo 11 had landed safely on the moon but could not take off, would there have been a rescue mission?

The following is a speech written for President Nixon, in the event that the Apollo 11 mission did not succeed. Fate has ordained that the men who went to the moon to explore in peace will stay on ...
Fred's user avatar
  • 13.1k
118 votes

What can the KSP game actually teach about spaceflight and orbital mechanics, and what are its limitations?

In my former job I was writing educational software. In short, it's exactly what you described: we offered a paid version of what you could get for free by looking out on the internet, going to class,...
Antzi's user avatar
  • 12.6k
100 votes

What can the KSP game actually teach about spaceflight and orbital mechanics, and what are its limitations?

In several press conferences, employees of NASA or private space firms have been asked if they played KSP, and some answered with "Yes". NASA used patched conics to find candidate orbits for ...
Polygnome's user avatar
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95 votes
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Would it be easier to put humans on Venus rather than Mars?

Technically, yes, it would be easier to put people on Venus. You need less of a kick for the interplanetary trip and slowing down is trivial with that dense atmosphere...one of the Pioneer Multiprobe ...
Christopher James Huff's user avatar
90 votes

What led NASA et al. to decide the ISS should be a zero-g station when the massive negative health and quality of life impacts of zero-g were known?

Reliability. Any rotating station needs non-rotating components: solar panels need to face the Sun, radiators need to be shadowed, docking points need to be non-moving, and so on. Making a rotating ...
Mark's user avatar
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88 votes
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Could "peak Apollo levels" of support have gotten NASA astronauts to Mars in the 1980's?

If you want to get really bummed out for 'what could have been', check out the Wikipedia page for List of manned Mars mission plans. The earliest plan to get to Mars was written by von Braun in 1948, ...
David Morris's user avatar
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72 votes
Accepted

Why was this Saturn rocket elevated for launch?

Your picture is not of a Saturn V, it's of a Saturn IB. The purpose of the elevated platform (known as the "milkstool") is to lift the rocket up so that it can be launched from Pad 39B using the same ...
Mark's user avatar
  • 15.3k
71 votes

How often is duct tape used during crewed space missions?

Gray tape was used during the Apollo missions, although only mentioned specifically by that name twice. The stowage manifests have several entries for tape. Although "duct tape" or "gray tape" is ...
DrSheldon's user avatar
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67 votes
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Why do ISS crew members often cross their arms?

It's about as standard procedure as crossing your legs when you're sitting. Arms in microgravity, without conscious effort to keep them by your body, will tend to extend the elbows to the sides - ...
SF.'s user avatar
  • 55k
66 votes
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Why can't we use the same radiation shielding in Mars that we used when going to the moon?

Radiation exposure is a cumulative risk. The more radiation you receive, the more likely you are to develop cancers. The Apollo missions took no more than two weeks to complete; the astronauts ...
Russell Borogove's user avatar
66 votes

Why can't we use the same radiation shielding in Mars that we used when going to the moon?

In addition to what Russell Borogove says about cumulative risk you're operating under a false assumption--that there was shielding on the Apollo capsules. Not only did the Apollo capsules not have ...
Loren Pechtel's user avatar
64 votes

Why do astronauts wear spacesuits during launch?

Are there failure modes that cause loss of pressure but not rapid, unplanned disassembly? Yes. The 3-man crew of Soyuz 11 died when a valve was jolted open, venting out all the cabin air supply. ...
Russell Borogove's user avatar
61 votes

Why were the SpaceX Crew-1 astronauts backed up by guards with automatic weapons?

Why were the SpaceX Crew-1 astronauts backed up by guards with automatic weapons? A NASA crew launch is a highly-visible symbol of US national pride. I mean, the slogan for the whole campaign is ...
Jörg W Mittag's user avatar
59 votes
Accepted

Did Apollo carry and use WD40?

It's hard to prove a negative, but the answer seems to be NO. It's not in D-7434 Stowage and the Support Team Concept, which has tables by location of the typical inventory stowed in the cabin. It's ...
DrSheldon's user avatar
  • 48k
58 votes

Why has the ISS not been left unmanned?

The ISS is a science laboratory -- a National Lab in fact. Leaving it uncrewed would take away a huge portion of the science productivity without substantially impacting the cost to operate it. Why ...
Tristan's user avatar
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57 votes
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Are all modern astronauts at least passable phlebotomists?

By my count, the OP asks three questions. I'll anecdotally answer two of them ("Is it something that most or all astronauts are capable of doing, or are there just a few "designated drivers&...
Digger's user avatar
  • 4,185
57 votes
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Why aren't spacecraft and spacesuits pressurised to 2.5 psi (17 kPa) of pure oxygen?

The sum of all partial pressures in the lungs must add up to the ambient pressure. The composition of gas inside the lungs includes the vapor pressure of H₂O at body temperature which is about 0.9 psi....
Woody's user avatar
  • 22.2k
56 votes

If the astronauts on Apollo 11 had landed safely on the moon but could not take off, would there have been a rescue mission?

The Apollo lunar module was battery powered, so could only maintain a livable environment for a few days (this was a major concern for Apollo 13, since the crew was reliant on the LM after the ...
Russell Borogove's user avatar
55 votes
Accepted

Could the Saturn V actually have launched astronauts around Venus?

It takes surprisingly little delta-v to reach Venus for a flyby -- about 3850 m/s from LEO instead of the 3200 m/s or so required to get to the moon -- so while the payload would have to be reduced ...
Russell Borogove's user avatar
55 votes
Accepted

If the ISS had an emergency, how long would it take to get a rocket to it?

A brand new rocket to be launched will have to be assembled, and that's a long process, though I do not know how long. But if it's for an emergency, you may find ready rockets. After the Columbia ...
Speedphoenix's user avatar
  • 5,324
54 votes

Why do ISS crew members often cross their arms?

Offered as a supplement to @SF's answer: This shows the fully relaxed arm position obtained by a sleeping astronaut. From here
Organic Marble's user avatar
54 votes

What led NASA et al. to decide the ISS should be a zero-g station when the massive negative health and quality of life impacts of zero-g were known?

I'll add one or two more items to Mark's excellent list. Stability - large rotating platforms (and they have to be large to produce useful artificial gravity) are subject to all sorts of precession. ...
Carl Witthoft's user avatar
53 votes

After the Crew Dragon's success, does Boeing's Starliner still offer value?

Commercial Crew awarded two providers for dissimilar redundancy. This is exactly why NASA decided to select two partners in the commercial crew effort. Having dissimilar redundancy is key in NASA’s ...
T.J. Tarazevits's user avatar
52 votes

How often is duct tape used during crewed space missions?

When I was in shuttle Endeavour's cockpit in May 2008 (the Orbiter was in the Orbiter Processing Facility) I noticed this duct tape applied to the aft Multifunction Display Unit. (personal photo) Two ...
Organic Marble's user avatar
50 votes

Would it be easier to put humans on Venus rather than Mars?

As others have already pointed out, getting humans to Venus would be marginally easier than getting them to Mars. Let's consider survival on Venus in a little more detail though. Although there haven'...
Jerry Coffin's user avatar
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
  • 6,180
50 votes

How did the Apollo guidance computers deal with radiation?

TL;DR: It was so busy getting stuff done, it didn't care. Being old, slow, massive and inefficient (by any modern standards, not by those in 1965) is a huge benefit when it comes to radiation hardness....
asdfex's user avatar
  • 15.1k
50 votes
Accepted

Can we write with chalk on blackboard in space?

There's no scientific reason against using a chalkboard, zero gravity isn't an impediment as making a mark is dependent on pressure between the chalk and the board. The reasons for not using chalk are ...
GdD's user avatar
  • 20.3k
48 votes
Accepted

Is there a mockup of the ISS on the ground?

There are multiple mock-ups of the ISS, for various purposes: The Space Vehicle Mockup Facility at Johnston space center contains replicas of many modules of the ISS, some of them assembled together. ...
SE - stop firing the good guys's user avatar
48 votes
Accepted

Why is it so hard to build crewed rockets/spacecraft able to reach escape velocity?

Delta-V to LEO is about 10 km/s. From there to C3 (Earth escape) is another 3.2 km/s. It's just another 30% delta-V. The problem is the Tyranny of the Rocket Equation. More delta-V means more fuel. ...
Schwern's user avatar
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