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1500 questions
73
votes
5 answers
Why is it easier to escape the solar system than get to Mercury or the Sun?
It has been mentioned several times on this site that it is "easier" (less delta-v, and hence less fuel) to reach the escape velocity of the solar system, than to reach the planet Mercury or the surface of the Sun:
Calculating solar system escape…
DrSheldon
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73
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2 answers
When will New Horizons overtake Voyager 1 in distance from the Sun?
Basically, what the title asks. To my understanding, New Horizons is currently the fastest spacecraft that's moving away from the Sun, with arguably only Helios-A and Helios-B possibly faster still, but in an elliptical orbit around the Sun, so they…
TildalWave
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73
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4 answers
Could we breathe an atmosphere that is not nitrogen based?
As I understand it, the important part of Earth's atmosphere that we breathe is the oxygen. However, Earth's air is only about 21% oxygen with the rest made up of about 78% nitrogen and 1% other gases, mostly argon.
Could we safely breathe the air…
Rozgonyi
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72
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3 answers
Did Feynman cite a fallacy about only circles having the same width in all directions as a reason for the Challenger disaster?
In a Math Overflow post about mathematical fallacies it was stated that:
Richard Feynman regarded the mistake that a "circle is the only figure
which has the same width in all directions" as one reason for the
space shuttle Challenger…
StayOnTarget
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71
votes
2 answers
Can a human land on Deimos using pressurized deodorant cans?
Can an astronaut use deodorant sprays which contain pressurized butane as cold gas thrusters to land on Deimos from Deimos' orbit?
If yes, how many cans would be required to get 5 m/s of delta-v for a human with and without a EVA suit?
What is the…
Ashvin
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5 answers
Why do SpaceX Starships look so "homemade"?
Maybe this is not possible to answer, but I was hoping there was some reliable information available on this.
It seems to me that the SpaceX Starship rockets have sort of a homemade quality to them, like they were made in someone's garage with basic…
PhilippNagel
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71
votes
9 answers
Which country borders are visible from space?
You can see the borders of North Korea with China and South Korea at night from the ISS since unlike their neighbours, they have almost no light. That got me thinking, which other country borders (of directly adjacent countries with no large bodies…
DarkDust
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71
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10 answers
Why is SpaceX considering Methane as fuel for their next engine, the Raptor?
Currently, SpaceX has developed the Merlin 1 family (1B (Falcon 1), 1C (Falcon 9 v1.0), 1D (Falcon 9 v1.1/F9-R/Falcon Heavy), vacuum versions and sealevel versions) which are LOX/RP1 based. (75-205Klbs thrust)
They developed (and abandoned) the…
geoffc
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Why did it take so long to notice that the ozone layer had holes in it? Which satellite provided the data?
Wikipedia says:
The discovery of the annual depletion of ozone above the Antarctic was first announced by Joe Farman, Brian Gardiner and Jonathan Shanklin, in a paper which appeared in Nature on May 16, 1985. (paywalled)
I believe the discovery…
uhoh
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1 answer
Why did the Apollo 13 crew extend the LM landing gear?
From the Apollo 13 radio transcript, as they're going through the Lunar Module activation checklist:
060:58:58 Lousma: Okay. The only item on page 10 is to deploy the landing gear.
060:59:06 Lovell: Okay, we'll do that now.
[Comm break.]
061:00:10…
Mark
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Why is using a space elevator cheaper than rocket power?
Why is rocket power so much less efficient? In both cases you want to lift a given weight a certain height. What does climbing a tether give you that you don't have when using rockets? Wouldn't a rocket following the same path as the elevator get…
Xavier Aaron
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70
votes
6 answers
Why does the ISS have to be destroyed?
ISS might be destroyed soon, de-orbiting for a controlled reentry into the Pacific Ocean.
Why isn't simply pushed away from Earth to an outer stable orbit (not sure if it's possible) or even into an interstellar space voyage?
Maybe it has not any…
Adriano Repetti
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70
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7 answers
Who coined the phrase 'Rapid Unscheduled Disassembly'?
Usually simply abbreviated as a RUD, and also sometimes expanded as Rapid Unplanned Disassembly, and being a way of understating that a rocket exploded.
I saw it attributed recently to Elon Musk, but although he has popularized the phrase among the…
kim holder
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1 answer
How far could we send someone before they get a lethal dose of radiation?
Given current technology, how far could we send someone before they get a lethal dose of hard radiation? What if they don't need to make a return trip? I know that last I had heard, Mars was too far to be able to take a return trip without being…
Danalog
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Why would SpaceX not use parachutes for the final descent of the first stage?
According to what I've read, SpaceX tried to use parachutes to recover the first stage of the Falcon 9, but it did not survive reentry.
Now they plan to use 2 separate rocket burns to land:
Reentry burn
Landing burn
I understand the reentry burn…
neelsg
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