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1500 questions
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How many astronauts never got to fly in space in their astronaut career?
We know that many people who take astronaut training and become astronauts may never get to fly to space at all.
How many astronauts (number or %, or both) have never flown to space in their astronaut career?
The percentage probably changed a lot…
James C
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19
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Minimum number of satellites to image the entirety of Earth's surface at all times
The simplest solution would be a tetrahedron, but as the satellites all need to orbit in circles, it seems this configuration would only guarantee full coverage at one time.
For simplicity, there's no minimum resolution requirement, the Earth is a…
Guillochon
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19
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Dawn Spacecraft: Why are the orbits so high?
I understand Dawn has a mission to undertake geologic ("Cereologic"?) mapping of Ceres, but its final orbit will be at 22,000 km / 49% disk illumination.
Surely, there would be some value for adding (or finalizing) on a much closer orbit for some…
Mikey
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19
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What contributes the majority of the mass in an ion drive?
In another question I've been corrected that batteries don't weigh that much in ion drive powered probes. Well, I thought a can of xenon would have a chance to be lighter than a solid block of plutonium, but truth of the matter, I have no…
SF.
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19
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Why do spacecraft enter the atmosphere violently instead of a smooth spiral?
Why do spaceships almost make a straight line in the atmosphere when coming back to earth? This makes the ship undergo high stress and temperature. Why don't they make a spiral trajectory so that they can slowly brake?
agemO
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19
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How accurately (maximum possible accuracy) can future satellite positions be predicted?
Agencies/organizations who own/operate satellites want to know their future positions after a certain amount of time. We know that models of satellite dynamics are imperfect and also perturbations effects are often hard to predict/quantize.
Given…
James C
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19
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How much sunlight gets to the surface of Titan? What would astronauts see?
Saturn being at 10 A.U. means sunlight on Titan's cloud tops is about 1/100 that on Earth's. That's 4000 times the illumination of Earth's moon. Titan's atmosphere is described as opaque smog. If it were 99.97% opaque the surface would still be…
Bob Stein
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19
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Are there any promising next-generation space station cooling technologies?
The ISS had problems related to ammonia more than once.
These problems happened in different calender years, and it seems like almost every "near miss" that makes the news about the ISS is connected to the ammonia loop. This system exists to…
AlanSE
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19
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Could the Apollo 13 crew have survived the CO2 issue using their spacesuits
In the book on the ill-fated Apollo 13 mission there is a chapter that contains an overview of the consumables on board the spacecraft, and whether or not they might pose a problem to the survival of the astronauts. Because the CDR and LMP were…
JDT
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19
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What limits the speed of space probes currently?
...other than budget, obviously.
Our computers nowadays are good enough that we should be capable of sending a probe to a neighbor star system and back, and get some pretty good analysis reports. We do have batteries that would survive a hundred…
SF.
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How much of the Interplanetary Transport Network is currently known?
The Interplanetary Transport Network is a network of mathematically-defined paths through our solar system that would require little to no energy for a spacecraft to follow them, albeit at very low speeds. While these pathways would not be practical…
Gwen
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19
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6 answers
How close can I get to a rocket launch and not get killed?
There was a question regarding the closest distance regular people are allowed to be near a rocket. At that distance (Baikonur I, 1.1 miles, 1.8 km), even if a rocket explodes, there is a small chance someone is getting killed.
What I ask you is how…
user6738
19
votes
2 answers
How much delta-v can we squeeze out of a gravitational slingshot and what factors limit it?
A lot of space probes use gravity assists from various space objects to boost their speed and save on propellant requirements. On what factors does the increase of delta-v depend? My guesses are:
Mass of object (the more massive, the…
user6738
19
votes
3 answers
How is the Quantum Drive performing on board the BARRY-1 cubesat?
Since 2001 there has been chatter about reactionless “quantum drives” such as the EmDrive developed by Satellite Propulsion Research Ltd. These drives supposedly produce thrust without consuming propellant or interaction with external fields. If…
Woody
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19
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What kept the Soviets from going to the Moon (before the US)?
I know that Saturn V's payload was 140 tons, about 20 times that of Soyuz. The Soviets did not have a functioning rocket with similar characteristics. But why? They had a head start in the space race by focusing on it early on. What kept them from…
MWB
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