86 votes
Accepted

What makes (or at least made) Ada the language of choice for the ISS's safety-critical systems?

This Wikibooks link lists its strong points, some of which are: An extremely strong, static and safe type system, which allows the programmer to construct powerful abstractions that reflect the ...
Morgloz's user avatar
  • 861
84 votes
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What safety protocols did this Pythom Space rocket crew ignore?

The easy-to-spot stuff: (assumed) Improper transportation of hazardous materials. Both white fuming nitric acid and furfuryl alcohol are considered hazardous materials; none of the vehicles in the ...
Mark's user avatar
  • 15.3k
77 votes
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Why would a box full of 1cm balls released into LEO be so scary to an engineer supporting the ISS?

Well, gee, this question may as well have my name printed directly on it! Spacecraft protection from the orbital debris threat comes in two flavors: Shield and withstand Detect and avoid To start, ...
Tristan's user avatar
  • 17.3k
62 votes

What makes (or at least made) Ada the language of choice for the ISS's safety-critical systems?

Timing. Ada was developed in the 1970s and 80s with the intent of replacing the plethora of languages used in the US Department of Defense's realtime systems. NASA (and also organizations from Europe) ...
David Hammen's user avatar
  • 74.8k
49 votes

Why is it assumed that space flights have to be safe?

But wouldn't it be better for space exploration if we inherently assumed space travel is incredibly risky and that astronaut deaths are to be expected? NASA and Roscosmos do assume space travel is ...
David Hammen's user avatar
  • 74.8k
47 votes
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Is it safe to observe the ISS with the naked eye?

It's safe. The ISS is about 100 meters across at its widest, and it's 400km away; this calculator tells me that makes an angular size of ~0.014 degrees. The sun's angular size is about 0.53 degrees....
Russell Borogove's user avatar
46 votes
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How did sloshing prevent the Apollo Service Module from moving safely away from the Command Module and how was this fixed?

Let's start with the "Statement of Problem" in the anomaly report. ...the service module, upon being jettisoned on a lunar return flight, should have entered the earth's atmosphere, then skipped ...
Russell Borogove's user avatar
42 votes
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Why does Blue Origin claim Virgin Galactic's spaceplane doesn’t have an escape system whereas Virgin Galactic's passengers are wearing parachutes?

First of all, it should be clear that this infographic is by no means objective; it's designed to put SS2 in the worst possible light, and New Shepard in the best. That said, an "escape system&...
Russell Borogove's user avatar
40 votes
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What is the primary reason for SpaceX motion to have astronauts board Dragon before fueling up the rocket?

The Merlin-1D engines are now tuned to use the super cooled fuel and oxidizer. Thus you would be running the engines in an out of normal state, if not using it the same as all other launches with ...
geoffc's user avatar
  • 79.6k
40 votes

Why is it assumed that space flights have to be safe?

I think you're mixing up public perception vs engineering reality. For example, you mention the space shuttle... if the Challenger disaster was treated as a cost of doing business, the Space Shuttle ...
Schwern's user avatar
  • 8,006
40 votes
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Wouldn't it make sense to use parachutes for aborting test flights rather than destroying the whole rocket?

The ability to successfully deploy a parachute still requires some level of stability or control, it's simply not an option for a badly out-of-control rocket. In cases where something goes wrong, the ...
Nuclear Hoagie's user avatar
33 votes
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Is the overall mortality rate for being in a spacecraft in space or bound for space about 4%?

It depends on how you count. Flights or individual astronauts: 302 manned spaceflights, 4 of which ended with a total of 18 fatalities: 1.3% of flights. 544 people have been in Earth orbit, ...
Hobbes's user avatar
  • 128k
32 votes

Why would a box full of 1cm balls released into LEO be so scary to an engineer supporting the ISS?

There's a few pieces of information that are needed to explain why one might be wary of 1 cm objects: Objects as small as 4 inches (about 10 cm) can be seen by radars or optical telescopes on Earth ...
called2voyage's user avatar
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30 votes
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How dangerous are RCS thrusters?

For Shuttle EVA, the Space Shuttle Flight Rules show that the safe distance for a suited crewmember was 27 feet for the main jets, 3 feet for the vernier jets, and 3 feet for the APU exhaust. It's ...
Organic Marble's user avatar
28 votes

Is it safe to observe the ISS with the naked eye?

No problem, even with a telescope Not only is it perfectly safe with the naked eye, it's also not a problem at all with a large aperture telescope. At first, I tried looking at the ISS with a 80-...
Eric Duminil's user avatar
  • 1,678
27 votes

Tiny emergency propulsive device if stuck floating in a large volume in microgravity

I found a real world test of this. Dan Barry tried it when STS-96 was docked to the ISS. I've scanned his account from the book "Space Shuttle: the first 20 years." tl;dr - he escaped by ...
Organic Marble's user avatar
27 votes

Why is dust such a problem in microgravity? Wouldn't proper air circulation and filtration take care of it?

When you have gravity heavy particulates like shavings, crumbs, large dust granules, etc. will fall to the ground where they can be cleaned or form part of the environment. In microgravity everything ...
GdD's user avatar
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25 votes
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Did the U.S. Space Shuttles have a way for crew to bail out?

They did, but its use case was pretty narrow. The shuttle hatch was modified to be able to be explosively jettisoned, and a telescoping escape pole (pictured below) could be deployed that would help ...
Tristan's user avatar
  • 17.3k
24 votes
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August 30th 2018 Soyuz leak, any dangers for re-entry?

The leak is in the Orbital Module (OM), which is jettisoned prior to re-entry, so there is no concern there. Source: link in the question. Image source: spaceflight101.com
Organic Marble's user avatar
22 votes

What is the primary reason for SpaceX motion to have astronauts board Dragon before fueling up the rocket?

In addition to not wanting to change anything for crewed launches (as geoffc mentioned), adding crew to a fueled vehicle is a seriously dangerous move. If you look at the AMOS-6 failure you'll see ...
John Aaron's user avatar
22 votes

What makes (or at least made) Ada the language of choice for the ISS's safety-critical systems?

I remember taking Computer Science courses in the late 90s. The professor of CS explained to our meager group of CS majors that he was going to teach us C, rather than COBOL or Ada, because it would ...
Machavity's user avatar
  • 7,905
21 votes
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What is the "ISS's Keep Out Sphere" and what is its radius?

NASA has made a list of requirements for spacecraft approaching the ISS. SSP 50808 is an ITAR controlled document that identifies the requirements for rendezvous, proximity operations, and ...
Hobbes's user avatar
  • 128k
21 votes
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Was this a rapid SCHEDULED disassembly? How was it done?

No. I think this is actually the May 23, 1965 A-003 test, described in my answer to the question, Could a spacecraft spin so fast that it spontaneously deconstructs? Notice that the rocket and Apollo ...
Tom Spilker's user avatar
  • 18.3k
20 votes

What does it mean for a launcher to be 'nuclear-certified'?

Really what it means is "Category 3" certified, with an additional review of a self-destruct situation to prevent breaking the nuclear payload. Category 3 is also what is required to launch humans, ...
PearsonArtPhoto's user avatar
  • 121k
20 votes
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Electronic Circuits for Safe Initiation of Pyrotechnics?

This excerpt from the Space Shuttle Systems Handbook Volume 2, drawing 13.1, (pdf page 200) shows a typical shuttle pyro circuit. (This one happens to be for the nose gear assist thruster, but they ...
Organic Marble's user avatar
19 votes

Tiny emergency propulsive device if stuck floating in a large volume in microgravity

What if you just carried a couple of uninflated balloons with you? If you ever get stuck, just inflate the balloon, and then hold it near your center of mass, aim it away from you, and let the air ...
Azendale's user avatar
  • 291
19 votes
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What is the ortho/para issue with LH2 as a fuel?

The problem is that the transition produces enough energy to boil the LH2. As explained on the old sci.space.history group: Skipping the gory quantum-mechanical details... there are two energy ...
Organic Marble's user avatar
19 votes
Accepted

How does the launch risk for a plutonium RTG and a uranium fission reactor compare?

The probability and consequences of a release of Pu-238 from an RTG in a launch accident are very low, due to the protections in place for such an incident. It's not like they never thought of that. ...
Mark Adler's user avatar
  • 58.2k
19 votes
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Did the Apollo missions fly "over the top" of the Van Allen radiation belts?

Not exactly "over the top" (still through the outer portion of the belts), but yes, it appears so, according to this source. There are simplified trajectory plots shown in the link. Also this source ...
Sergiy Lenzion's user avatar
18 votes

How are the "lucky JPL peanuts" shared post-pandemic?

People received individual packages of peanuts and could sneak one under their mask. This page shows people holding individual packages of peanuts. And this video explains the procedure briefly.
Wyck's user avatar
  • 1,584

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