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120 votes

A starship is traveling at 0.9c and collides with a small rock. Will it leave a clean hole through, or will more happen?

@Hobbes answered this in a comment. Your final guess Will it collide with enough energy to initiate fusion with the atoms of the hull? is correct. See the first XKCD What-If comic, "Relativistic ...
Dan Pichelman's user avatar
89 votes

Is the SpaceX Falcon Heavy payload (a Tesla car) space junk?

No, because it is not in Earth orbit First the payload does have a purpose: it is a boilerplate, and those have a purpose, namely to "test various configurations and basic size, load, and handling ...
MichaelK's user avatar
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68 votes

Why are there mountains/mounds in the centre of craters on the lunar surface?

Oh, I can answer this one. In my structural geology class, we breezed over a few paragraphs on the tectonics of impact craters, but it was in the textbook, and, being space-related, I was intrigued. ...
Anton Hengst's user avatar
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63 votes

Is the SpaceX Falcon Heavy payload (a Tesla car) space junk?

Yes, it's space junk: after about 6 hours, the second stage will stop working and there will be no way to change the trajectory of stage and payload. So it's a non-functional satellite, i.e. junk. An ...
Hobbes's user avatar
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53 votes

Does NASA have an end-of-the-world policy?

First off, large life-ending asteroid impacts are very rare as there aren't many of them out there and we've found almost all of them: Looking at the 'continent' and 'global catastrophe' areas of ...
astrosnapper's user avatar
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50 votes

BBC: "A rocket launched by Elon Musk's space exploration company is on course to crash into the Moon and explode." Will it really explode?

It depends on how you define "explosion". Most generally, it merely describes something that breaks into pieces violently. Astronomical impact events can generate explosions simply from ...
Nuclear Hoagie's user avatar
42 votes

Is the SpaceX Falcon Heavy payload (a Tesla car) space junk?

Footnotes: ${}^1$ That the term "Space Junk" (as used in this answer and which is probably the right answer) has a different generally agreed meaning in spacecraft lingo than just plain "Junk" has ...
uhoh's user avatar
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35 votes

A starship is traveling at 0.9c and collides with a small rock. Will it leave a clean hole through, or will more happen?

I answer this question from a purely structural-mechanical point of view, i.e. not considering fusion as discussed in Dan Pichelman's answer. Will it create a football sized hole through the ship ...
Everyday Astronaut's user avatar
32 votes

BBC: "A rocket launched by Elon Musk's space exploration company is on course to crash into the Moon and explode." Will it really explode?

I think it's worth looking at how much energy that rocket is going to be carrying. Plugging the 4 tonnes and 5000 mph figures into an Online calculator we find that the impact will carry close to 10 ...
Jack Aidley's user avatar
27 votes
Accepted

If a Voyager crashes into something, would we know?

Most likely no. Voyager downlink communication (via its radio link to NASA's Deep Space Network (DSN) is not continuous. You can check the contact schedule at this Voyager site. If everything looks ...
Tom Spilker's user avatar
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26 votes

A starship is traveling at 0.9c and collides with a small rock. Will it leave a clean hole through, or will more happen?

Let us consider a 10 kg rock with a $0.1\,\mathrm{m}^2$ cross-sectional area. Further let’s assume that we are lucky and the rock passes only through one wall of the spaceship (say $3\,\mathrm{mm}$ of ...
Steve Linton's user avatar
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26 votes
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How did two satellites end up in almost the same orbit except moving in opposite directions?

How? Simple, because they launched into those orbits. Why? Well, first, let me explain what their orbits actually are. IRAS (13777) and GGSE-4 (2828) are both in high-inclination orbits, 70° and 99°...
Anton Hengst's user avatar
  • 10.7k
24 votes

Why not crash the ICPS into the Moon?

The upper stage for Apollo 8 through Apollo 12 were sent into heliocentric orbit. On the last five flights, Apollo 13 through Apollo 17, the upper stages were instead intentionally crashed into the ...
David Hammen's user avatar
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21 votes
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Can a nuclear detonation on Moon destroy life on Earth?

Probably not. Just to give you an idea, lunar rocks hit the Earth on a somewhat regular basis. The power required to have a rock hit Earth is equivalent to that of making a 450 m crater. This comes ...
PearsonArtPhoto's user avatar
  • 121k
21 votes

BBC: "In 2009 Prof McDowell & other astronomers performed an experiment in which a similar-sized rocket was crashed into the Moon." Really? Which one?

"2009 impact" would probably be when the LCROSS/LRO upper stage was crashed into a crater at the Moon's south pole. The LCROSS Centaur upper stage had a mass at impact of around 2300 kg; an ...
Mark's user avatar
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19 votes

Is the SpaceX Falcon Heavy payload (a Tesla car) space junk?

It depends. In the industry, the concern with space junk is whether or not certain objects are a navigational hazard. If the Falcon Heavy payload were on a collision course with an active spacecraft, ...
called2voyage's user avatar
  • 23.7k
19 votes

How many satellites can stay in a Lagrange point?

Lagrange points as I understand it are points in space between 2 objects where the gravitational pull between them is effectively equal. A quick check of Wikipedia's Lagrangian point or any article ...
uhoh's user avatar
  • 149k
16 votes
Accepted

How can we avoid collisions when moving from one orbit to another?

Exactly the same way you avoid collisions when not altering orbit. Altering your orbit does not significantly alter your risk of collisions, other than possibly moving you to a higher or lesser ...
CuteKItty_pleaseStopBArking's user avatar
14 votes

BBC: "A rocket launched by Elon Musk's space exploration company is on course to crash into the Moon and explode." Will it really explode?

Energy-wise, I'd call it an explosion Kinetic energy (KE) = 1/2 mv2 The article quotes the mass at 4 tons, and the speed as 5,000 mph. That gives: KE = 0.5 * 3628 kg * 2235 m/s * 2235 m/s = 9 ...
codeMonkey's user avatar
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14 votes
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Have any bits of a space mission ever collided with a planet or large moon (not Earth) that was not a target of the mission?

Yes https://scitechdaily.com/space-junk-just-crashed-into-the-far-side-of-the-moon-at-5800-mph/ A piece of space junk (China or spaceX) hit the far side of the moon
Catprog's user avatar
  • 434
14 votes
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How likely is it that the Voyager spacecrafts haven't yet been damaged by micrometeoroids?

This is a great question, I'm no planetary scientist but I'll give a partial answer to get things started. Interplanetary dust is ubiquitous in the solar system and interplanetary spacecraft including ...
uhoh's user avatar
  • 149k
13 votes

Why are there mountains/mounds in the centre of craters on the lunar surface?

It's actually a rebound effect that occurs with an impact forming a large crater. https://www.lpi.usra.edu/education/explore/shaping_the_planets/impact-cratering/ explains: Central peaks – Peaks ...
Oscar Lanzi's user avatar
  • 8,525
13 votes

Why are there mountains/mounds in the centre of craters on the lunar surface?

It might help to compare the crater formation to a drop impact: It seems that rock can behave like a viscous mass if you hit it fast enough.
Eric Duminil's user avatar
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12 votes
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Would the one million people on Mars be killed by an impact equivalent to an Extinction Level Event on Earth

I would guess no. What makes the extinction level events so dangerous for us isn't the impact or the shockwave. A shockwave on Mars won't do much damage since the atmosphere is very thin anyway, and ...
Innovine's user avatar
  • 4,625
10 votes
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How might one approach using AI (convolutional neural network) to predict collisions in orbit?

As a data scientist with an interest in space stuff, I am well positioned to give an answer this question. I must confess I don't understand fully what is going on in this system from just the lecture ...
Ingolifs's user avatar
  • 6,458
10 votes

A starship is traveling at 0.9c and collides with a small rock. Will it leave a clean hole through, or will more happen?

Probably the spaceship is destroyed. The big problem is that the energy of the rock-spaceship collision is large. So large that even if a trivial amount is deposited into the spaceship, the ship is ...
Yakk's user avatar
  • 573
9 votes
Accepted

Is Starman/Roadster in any danger in the asteroid belt?

Is Starman/Roadster in any danger of asteroid belt? Honestly? No. The Asteroid belt does contain lots of asteroids. But this is deep space. These things are not close together in any sense. Think ...
Simba's user avatar
  • 206
8 votes
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What prevents all these man-made objects flying in space from colliding with each other?

Douglas Adams summed it up perfectly "Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that'...
geoffc's user avatar
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8 votes

How often do active satellites have to change course to avoid other active satellites?

Per the most recent (March 2022) Orbital Debris Quarterly News issued by NASA, the International Space Station has conducted 30 orbital debris avoidance maneuvers since 1999. That's a bit over one per ...
David Hammen's user avatar
  • 74.9k
7 votes
Accepted

Which two satellites had a 44% probability of collision at 2017-01-07 21:53 UTC?

First of all, it was a miss. Whew! The close approach predicted at 21:53:00 UTC on 7 Jan 2017 has passed without incident. The JSpOC has confirmed that both satellites are being tracked as single ...
PearsonArtPhoto's user avatar
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