Hot answers tagged

107 votes
Accepted

Which country borders are visible from space?

The border between India and Pakistan is one of the most heavily guarded and well-lit borders in the world, so much so that it can be seen from space at night. It covers an immense distance from the ...
karthikeyan's user avatar
  • 4,479
91 votes

What did the Soviet Union and Russia bring to the ISS?

Initially, everything. The ISS started out as Mir-2 with some extra modules added soon afterwards. Then lots more over the next 10 years. The initial modules, Zarya and Zvezda, which housed living ...
geoffc's user avatar
  • 79.4k
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
  • 14.7k
85 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
  • 851
80 votes
Accepted

This image of the Space Shuttle is truly beautiful, but is it real?

This image is very similar to the following image https://spaceflight.nasa.gov/gallery/images/shuttle/sts-130/html/iss022e062672.html with the following description STS-130 Shuttle Mission Imagery ...
OON's user avatar
  • 1,694
77 votes
Accepted

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
76 votes
Accepted

Why does the ISS have to be destroyed?

The ISS is not designed to be run unmanned, entirely. The staff on board, when there are 6 astronauts, between exercise, sleeping, and maintenance get a single person-day of science work completed. (...
geoffc's user avatar
  • 79.4k
76 votes
Accepted

Is the zero gravity experienced in ISS the "artificial" kind?

Gravity is everywhere. There is never any actual true "zero gravity" in the universe. But if you're in freefall - meaning following gravity's pull rather than resisting it, or being blocked ...
Stilez's user avatar
  • 1,886
72 votes
Accepted

Would all crew leave the ISS if one had a medical emergency?

All of the crewmembers assigned to the sick crewmember's crew transport vehicle (which as of this writing means the Soyuz) would have to leave as well. Otherwise they would be left without a means of ...
Organic Marble's user avatar
68 votes
Accepted

Why vent $CO_2$ and $H_2$ waste products to space on ISS?

Added complexity is never welcome in a situation where lives are on the line and help isn't a phone call away. There have been a number of ammonia-related events and those are in systems that should ...
uhoh's user avatar
  • 149k
67 votes
Accepted

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
64 votes

Why aren't the 'bedrooms' aboard the ISS also the escape pods?

Primarily, because without a lot of extra equipment, they could at best be space coffins for the astronauts. First, they share life support with the rest of the station. Air circulated through them ...
SF.'s user avatar
  • 55k
62 votes

What are these green text/line displays shown during the livestream of Crew Dragon's approach to dock with the ISS?

The display shown is from the screen of one of the Space Station Computer laptops in the US Lab. This was being downlinked to Mission Control in Houston to monitor the functioning of tools used by ...
Erin Anne's user avatar
  • 10.8k
61 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
  • 73.8k
60 votes
Accepted

What language is software running on the ISS written in?

Almost all of the safety critical software that runs on the US side of the Space Station is written in Ada. I wrote "almost all" rather than "all" because there are probably some low level device ...
David Hammen's user avatar
  • 73.8k
58 votes
Accepted

What's the baseball bat for? (seen in CRS-8 berthing NASA TV broadcast)

The baseball bat is for "Attitude adjustment", apparently :) Source: Arstechnica photos of ISS control room (ADCO=Attitude Determination and Control officer) Here's a better pic of the bat from the ...
Andy's user avatar
  • 5,178
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
  • 17.3k
58 votes
Accepted

Evacuating the ISS but wait, there's only one Spacecraft?

By design that will never happen. There are always enough return seats for the crew. This is exactly why the whole crew of one of the visiting vehicles gets in it whenever it undocks, even when it is ...
Organic Marble's user avatar
56 votes
Accepted

Why do they have a Snellen eye chart on the ISS?

Eyes do strange things in microgravity (when you consider they're deformable bags of fluid, this isn't too surprising). This report outlines the changes that can be identified after just a short ...
Andrew is gone's user avatar
56 votes
Accepted

Does the ISS have a watch system with at least one person monitoring at all times

It definitely does, and not just one person - except these people are ground-based. The astronaut crew is only a small fraction of the number of people operating, controlling and maintaining ISS. ...
SF.'s user avatar
  • 55k
56 votes

ISS Structural Integrity

"Is that really all that holds it together?" Well, no. There are several different attach mechanisms used to hold the various parts of the ISS together. The mechanism used depends on what kind of ...
Organic Marble's user avatar
55 votes

Why does there appear to be a 180-degree stereo microphone array outside the ISS?

That is a UHF antenna. It was well placed on the Lab to get in the way of robotics ops during space station assembly. This is a picture of a different UHF antenna unit (this one is on the P1 truss ...
Organic Marble's user avatar
55 votes
Accepted

What caused this bright light from the ground at night seen from the ISS?

Well I confirmed via Google Maps that this is Mecca. As shown in the map and image below the roads align with those lighted in the image. The dark areas in the first image are steep hills to the ...
Josh King's user avatar
  • 2,419
55 votes

How can I, a high school student in Bucharest, go on to become an ISS astronaut?

As Antzi states, NASA only employs US nationals in its astronaut corps. However, Romania joined ESA (the European Space Agency) in 2011 and ESA has its own astronaut corps. As a Romanian national you ...
stuart10's user avatar
  • 641
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
52 votes
Accepted

Why use water tanks from a retired Space Shuttle?

They're already made, have plenty of usable life left, were stored in a way that facilitates reuse, and apparently cost less than building and certifying brand new ones. https://www.nasa.gov/feature/...
ceejayoz's user avatar
  • 1,278
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
  • 1,746
51 votes
Accepted

How do ISS astronauts "get their stripes"?

They're simply visual differences for identification. After Apollo 11, folks on the ground had a hard time finding photos of Armstrong on the moon. Most photos were taken by him and there was no ...
BowlOfRed's user avatar
  • 6,842

Only top scored, non community-wiki answers of a minimum length are eligible