4 ms·

Empty end hits first, dispersing a lot of force. Motor end rotates around still carrying a lot of force and impacts leaving a second crater. Or am I missing so

Empty end hits first, dispersing a lot of force. Motor end rotates around still carrying a lot of force and impacts leaving a second crater. Or am I missing something that makes this newsworthy?

jahnu 4y ago
From TFA, "No other rocket body lunar collision has ever created two craters to our knowledge."
- Grimburger 4y ago
  How many of those are there?
  - jfk13 4y ago
    According to https://www.nationalgeographic.com/science/article/a-rogue-rocket-part-is-about-to-collide-with-the-moon https://www.nationalgeographic.com/science/article/a-rogue-r..., this was "the first known event of its kind". So I guess we don't have much to compare with...
    - KMag 4y ago
      That's not a great source. By "of its kind" they must mean accidental booster stage impacts. NASA intentionally crashed 5 different Saturn V 3rd stages into the moon. At least some of those impacts were to generate vibrations for the seismometers they installed on the moon. See the Wikipedia article linked by the sibling post.
  - jahnu 4y ago
    Sort by status: https://en.wikipedia.org/wiki/List_of_artificial_objects_on_the_Moon https://en.wikipedia.org/wiki/List_of_artificial_objects_on_...
mannykannot 4y ago
I think it is implied in the article that only the motor is massive enough to excavate a crater. The similarity in size of the craters suggests they were created by objects of similar mass. At least one early rocket design (Atlas) had fuel tanks so insubstantial that they had to be pressurized until they were loaded with fuel on the pad, and a loss of pressure could be expensive... https://www.youtube.com/watch?v=imkdz63agHY https://www.youtube.com/watch?v=imkdz63agHY
- rob74 4y ago
  That could still work: when the empty end hits first, it has the mass of the engine(s) behind it, and obviously after it bounces/rotates, the engine(s) hit the ground directly and use up the rest of the momentum. But this is just guessing on my part - and of course, if the Moon's gravity would rotate the engine downward as another commenter suggests, it wouldn't work out this way...
  - mannykannot 4y ago
    With the mass of the motor behind it, I would guess the fuel tank would crumple like an empty beer can smashed against the rocks.
N19PEDL2 4y ago
> Empty end hits first In reality, the motor end should hit first, since free-falling objects usually rotate in such a way that the heaviest part is positioned at the bottom. The atmosphere could influence and modify this behaviour on other celestial bodies, but the Moon does not have it.
- hibbelig 4y ago
  > In reality, the motor end should hit first, since free-falling objects usually rotate in such a way that the heaviest part is positioned at the bottom. The atmosphere could influence and modify this behaviour on other celestial bodies, but the Moon does not have it. Interesting. How does that happen without atmosphere? I thought the atmosphere is what creates this effect in the first place.
- deleted 4y ago
  [deleted]
- Zardoz84 4y ago
  if you are right, on vacuum, a heavy mass should fall faster that a light mass...
  - deleted 4y ago
    [deleted]
adamcharnock 4y ago
I don't think anything manmade and space-borne is going to have enough structural integrity to perform any kind of summersault upon impact at that velocity. See the fighter jet vs concrete wall video [1]. That was going at 500mph, and notice how the tail of the craft doesn't even perceptibly slow down. And a change in velocity would be required for the tail to rotate around (whether the impact is on an angle or head on) This space object was travelling at 5800mph, 11+ times the speed. Sure a meter or so of moon dust may be a bit softer, but its solid rock underneath right? I'd guess the equivalent would be putting a kitchen sponge between that fighter jet & concrete wall. [1] https://www.youtube.com/watch?v=F4CX-9lkRMQ https://www.youtube.com/watch?v=F4CX-9lkRMQ

Empty end hits first, dispersing a lot of force. Motor end rotates around still carrying a lot of force and impacts leaving a second crater. Or am I missing something that makes this newsworthy?

jahnu 4y ago

From TFA, "No other rocket body lunar collision has ever created two craters to our knowledge."

Grimburger 4y ago
How many of those are there?
- jfk13 4y ago
  According to https://www.nationalgeographic.com/science/article/a-rogue-rocket-part-is-about-to-collide-with-the-moon https://www.nationalgeographic.com/science/article/a-rogue-r..., this was "the first known event of its kind". So I guess we don't have much to compare with...
  - KMag 4y ago
    That's not a great source. By "of its kind" they must mean accidental booster stage impacts. NASA intentionally crashed 5 different Saturn V 3rd stages into the moon. At least some of those impacts were to generate vibrations for the seismometers they installed on the moon. See the Wikipedia article linked by the sibling post.
- jahnu 4y ago
  Sort by status: https://en.wikipedia.org/wiki/List_of_artificial_objects_on_the_Moon https://en.wikipedia.org/wiki/List_of_artificial_objects_on_...

mannykannot 4y ago

I think it is implied in the article that only the motor is massive enough to excavate a crater. The similarity in size of the craters suggests they were created by objects of similar mass. At least one early rocket design (Atlas) had fuel tanks so insubstantial that they had to be pressurized until they were loaded with fuel on the pad, and a loss of pressure could be expensive... https://www.youtube.com/watch?v=imkdz63agHY https://www.youtube.com/watch?v=imkdz63agHY

rob74 4y ago
That could still work: when the empty end hits first, it has the mass of the engine(s) behind it, and obviously after it bounces/rotates, the engine(s) hit the ground directly and use up the rest of the momentum. But this is just guessing on my part - and of course, if the Moon's gravity would rotate the engine downward as another commenter suggests, it wouldn't work out this way...
- mannykannot 4y ago
  With the mass of the motor behind it, I would guess the fuel tank would crumple like an empty beer can smashed against the rocks.

N19PEDL2 4y ago

> Empty end hits first In reality, the motor end should hit first, since free-falling objects usually rotate in such a way that the heaviest part is positioned at the bottom. The atmosphere could influence and modify this behaviour on other celestial bodies, but the Moon does not have it.

hibbelig 4y ago
> In reality, the motor end should hit first, since free-falling objects usually rotate in such a way that the heaviest part is positioned at the bottom. The atmosphere could influence and modify this behaviour on other celestial bodies, but the Moon does not have it. Interesting. How does that happen without atmosphere? I thought the atmosphere is what creates this effect in the first place.
deleted 4y ago
[deleted]
Zardoz84 4y ago
if you are right, on vacuum, a heavy mass should fall faster that a light mass...
- deleted 4y ago
  [deleted]

adamcharnock 4y ago

I don't think anything manmade and space-borne is going to have enough structural integrity to perform any kind of summersault upon impact at that velocity. See the fighter jet vs concrete wall video [1]. That was going at 500mph, and notice how the tail of the craft doesn't even perceptibly slow down. And a change in velocity would be required for the tail to rotate around (whether the impact is on an angle or head on) This space object was travelling at 5800mph, 11+ times the speed. Sure a meter or so of moon dust may be a bit softer, but its solid rock underneath right? I'd guess the equivalent would be putting a kitchen sponge between that fighter jet & concrete wall. [1] https://www.youtube.com/watch?v=F4CX-9lkRMQ https://www.youtube.com/watch?v=F4CX-9lkRMQ