Whatever hit the Moon in March, it left a double crater

[DoctorOetker]

Does a similar high resolution image of the same region before date of impact exist? If so it would significantly strengthen the claim that both craters are due to the same recent impact.

Looking at the density of craters how can we exclude the possibility that one of the craters simply existed before the new one?

What alternative scenarios have been considered and ruled out? It would be nice to see what other explanations were considered but ruled out, and how it was ruled out. For example, did the object hit a lava tunnel? (I don't think so, nor do I see how it could explain a double crater, but I would like to see the thought processes of elimination of hypotheses).

If the conclusion is correct, what was the second mass on the opposite end of the rocket motor? Is it some taboo failed project? A "stillborn" crew capsule?

EDIT: the linked references actually show before and after images:

https://www.nasa.gov/feature/goddard/2022/nasas-lunar-reconn...

[stouset]

> Looking at the density of craters how can we exclude the possibility that one of the craters simply existed before the new one?

One thing to note is that the density of craters on the moon is a result of a relatively infrequent number of impacts over an astronomically long time. With no process by which impact craters are weathered (wind, seismic activity), craters remain essentially forever.

[jstanley]

Isn't the obvious answer that it was actually 2 objects very close together?

Or would we expect them to have drifted far enough apart by the time they hit the moon that the craters would not be so close?

[compiler-guy]

To this layman who knows very little about orbits and impact craters, that explanation makes a lot of sense.

But the professional software engineer in me knows that even people well skilled in adjacent fields dont understand the issues that makes things “obvious” in my own field.

I therefore don’t doubt that the experts who study space debris considered the obvious explanation and rejected it. Or concluded that it wasn’t as obvious as it may seem.

That they are willing to defer to the crater-formation expert shows an admirable humility and deference to someone who is far more likely to know.

[simonh]

It's highly unlikely they would remain that close unless they split apart very soon before impact. Solar radiation exerts a small force on any object in space that depends on the object's orientation, reflectivity, rotation, etc. This introduces a small variation in it's flight path that can add up to several kilometres of uncertainty in just a few weeks. So even objects with very close flight paths, but differences in structure and rotation, will diverge. Objects with low mass to surface area and an elongated shape, such as empty fuel tanks, are subject to particularly high uncertainty in their trajectory.

[BurningFrog]

> (18-meter diameter, about 19.5 yards)

This is an unfortunate mix of precision and approximation.

[bombcar]

I love the machine-generated ones, where it'll say "1 kilogram, or 2.20462 lbs".

[pitaj]

I could understand if they went to 59 feet. But yards are roughly the same as a meter. Why even bother?

[antod]

The replies to this make me think I've found "my people". Can we form a group?

[happyopossum]

Why? Those are both close enough for the intended purpose. 20 yards would be too imprecise, and 19 yards 24 inches is too wordy...

[cheschire]

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?

[mannykannot]

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

[adamcharnock]

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

[jahnu]

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

[N19PEDL2]

> 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.

[DiabloD3]

Possibly an electrostatic discharge "crater" as distance was finally short enough to be bridged by potential, and then the second crater is the actual impact.

[guerrilla]

Is that more plausible or probable than two small objects spread out very slightly in the tangent plane and also a bit in time? They say "the" object a lot but is that something we have the precision to know, i.e. that it was not two objects instead? What I really want to know is if static discharge of that magnitude is common? If so, that's kinda cool.

[ianai]

Since it seems the suspicion is it being a Chinese booster, two craters makes me wonder if the booster blew up during it’s active mission but remained tethered together. Not like explosions are known to routinely follow expectations.

[karmicthreat]

The government decided to finally take out the Moon because it was interfering with local tv channels.

[shreyshnaccount]

Thing hit moon, impact launched another thing up, which then fell close by?

Idk anything about orbits, so the experts have prolly already rejected this hypothesis

[GEBBL]

Does the moon take a lot of impacts that would have been destined for earth?

[jstanley]

Most of the stuff that leaves a small crater on the moon would burn up in Earth's atmosphere long before it hits the ground.

[tiffanyh]

Random Factoid: it's extremely rare but the reason why the moon appears the same size as the sun is that the sun is 400x wider than the moon, but also 400x farther from the earth than the moon is.

Our moon holds so many mysteries. Just the very fact that such a large object can be so close in proximity to us while also orbiting is mind boggling.

https://astronomy.com/magazine/ask-astro/2000/10/why-is-the-...

[MonkeyClub]

I have the same question, if anyone knows the answer it'd be awesome.

I mean, sure, simply by virtue of the moon's being there, it sort of fends some stuff off like a fence.

But beyond that, is its gravitational pull adequate to affect trajectories?

If so, wouldn't earth's trump it? (Although the inverse square here may play a big part, but that would also make me more inclined to disregard the moon's gravity pull as assisting in any protection it otherwise naturally affords.)

Edit: clarified (?) thought

[iamgopal]

That would be Jupiter and Saturn. For this instance, it’s other way around.

[BurningFrog]

About as much as the percentage of the sky it covers, I assume?

[BurningFrog]

Do we have a good enough camera in orbit to look at the debris?

With no atmosphere, the conditions for that should be ideal.

[Fatnino]

LRO is that camera and that's what took the picture we have.

It's getting up there in years so we could probably build something better today but we haven't yet.

[BurningFrog]

I also have a hunch/theory:

It happened to hit a ridge of hard rock, which withstood the impact unchanged.

[Jerrrry]

Material science is moot at astronomical impact forces.

A meteorite hitting sand will make the same impact as if it hit steel.

[giantg2]

Finally, a proper label for the opposite of double rainbow - double crater.

[swayvil]

The object was probably longish and cylindrical-ish. Like a baguette. Hit, broke in half, then the other end hit.

[invisible]

Could it not be that one is an impact crater and the other is blasted out from an explosion?

[Maraguy]

Does this mean its even more dangerous to setup a moonbase?

[Melatonic]

Send over the Chinese rover to investigate!

[bluelightning2k]

Was it crypto?

I have it on good authority from some rather artificial-sounding YouTube comments that that they were planning on going to the moon.

raies hand for high five. Gets left hanging...

[BeefWellington]

I mean it definitely cratered...

[mcv]

I was thinking it might have been GME or AMC.

Maybe I've been hanging out on /r/WSB too much.

[eyko]

Got you -- :high_five:

Although my 2¢: it was a good joke until the second paragraph. That killed it for me – if I'm fed the explanation there's no more fun in "getting" it.

[crikeyjoe]

I think it might have been the Indian lunar probe that crashed into the moon.

[bratbag]

'space junk' has long been used as a colloquial term for human generated debris in space, sourced from all nations. This material was discarded by China.

Anything more that you read into that, may be due to some heightened sensitivity that your own flavour of propaganda has installed in you.

[jfk13]

The Register's style is to use every bad pun, innuendo, or corny joke they can find. They'd do the same regardless of the nationality involved.

[delaaxe]

Being offended at the phrase « Chinese junk » is peak woke virtue signaling