Space junk on a 5,800-MPH collision-course with moon on Friday | Hacker News Reader

Space junk on a 5,800-MPH collision-course with moon on Friday

latimes.com

42 pointsNews-Dog40 comments

I hope some of the currently active missions on the Moon can record some data from the event. The lunar seismometers placed during Apollo are no longer active. [0]

[0] https://en.wikipedia.org/wiki/Lunar_seismology

DuckDuckGo - Search > ' Dust-Detector-Moon '

<https://html.duckduckgo.com/html?q=Dust-Detector-Moon>

Exactly what I was thinking... it's too bad they shut down due to a lack of funding of all things...

there has been concerns about ships landing on Moon raising dust hanging around for long and thus causing issues for the following landing/launches. Looks like we're beginning such a pollution of the near-Moon space.

Wouldn't asteroid (more common due to no atmosphere) impacts cause similar pollution?

Yes, and the amount of dust would probably be proportional to the energy they carry to the impact point, and their trajectory relative to the surface.

But the moon doesn't have an atmosphere. Surely there's nothing for the dust to "hang around" in. It would either achieve escape velocity or continue in an arc until it hits the ground again.

Wouldn't the dust technically become the atmosphere? There is still gravity on the moon.

> Wouldn't the dust technically become the atmosphere?

No, because it's not a gas (dust has basically zero pressure) and it won't stay aloft at a constant or nearly constant altitude. It will either fall back to the surface or escape.

I have a hard time believing that the dust would escape given the gravity of the moon.

> douldn't the dust technically become the atmosphere?

Only for short time, while it's vaporised into a gas by the impact. For that time it will join the rest of the "infinitesimal amount of gas" that forms a very tenuous atmosphere around the moon.

https://www.nasa.gov/mission_pages/LADEE/news/lunar-atmosphe...

Dust is generally held in suspension by the air here on Earth, because of the air currents and because of air viscosity. With no atmosphere on the moon, I suspect the dust would not stay suspended above the surface very long.

> It would either achieve escape velocity or continue in an arc until it hits the ground again.

Correct. IDK about impacts, but for rocket exhausts, the surprising result is that some of the kicked-up dust can achieve escape velocity, and "where it hits the ground" is "anywhere on the moon" - denser nearby, obviously, but there's no 100% safe distance anywhere on the lunar surface.

https://www.theverge.com/2019/7/17/18663203/apollo-11-annive...

Moon gets struck by meteorites all the time... dust kicked up by landings or man-made impacts isn't really a problem that warrants concern.

maybe the issue is takeoffs more than landings

> dust kicked up by landings or man-made impacts isn't really a problem that warrants concern

In general no. With regards to other human people and hardware that might be on or near the moon when it's kicked up, it definitely is a concern.

NASA once calculated, "when a rocket lands on the moon, or launches, how far can the kicked-up dust travel?". And got the answer "everywhere on the moon is in range. Some dust will also escape the moon."

https://www.theverge.com/2019/7/17/18663203/apollo-11-annive...

> that could be bad news for any future habitats that NASA or other space agencies might want to build on the Moon

> “It could ruin a spacecraft in orbit around the Moon if it just happens to be in the wrong place at the wrong time,”

> will be sand-sized stuff blown completely off the Moon into orbit around the Sun.

Generally the plan is to put down a pad once you've got the first ship there.

There's some cool NASA concepts around for what is basically a household microwave with wheels that melts the regolith into a ceramic type material.

https://space.stackexchange.com/questions/35319/can-you-real...

How well does regolith absorb microwaves?

According to the parent comment's link "Tiny specks of metallic iron (Fe0) are embedded in each dust particle's glassy shell [...] microwaves melt lunar soil in less time than it takes to boil a cup of tea"

That's unexpectedly convenient for this plan!

Dark side of the moon! I’m queuing up Pink Floyd Friday.

Is there nowhere we won't descrate?

The moon is an ideal place to desecrate.

Public service: 9334 km/h.

thank you sir for this.

Many LOL's - Thanks! - I needed That!

2593m/s or 2.6km/s. Not sure if they're more common in the industry, but they certainly are in Kerbal Space Program.

0.0008649% the speed of light

1.56*10^7 furlongs per fortnight

Would this be its speed relative to the moon?

That is a very interesting question! I wanna know too.

Also,

> 3 tons of space junk, a punch that will carve out a crater big enough to fit several semitractor-trailers

These are likely US tons, so 2722kg. I'm not sure about the SI conversion of the semitractor-trailer units.

> scientists expect the object to carve out a hole 33 feet to 66 feet across

Oh, so 10-20 meters :-)

> 33 feet to 66 feet across

I loled at this. It was so obviously 10 - 20 meters.

Should probably just say "About 50 feet in size"

> > 3 tons of space junk, a punch that will carve out a crater big enough to fit several semitractor-trailers > These are likely US tons, so 2722kg.

Earlier reports put the mass at explicitly "4 metric tons" [0][1], so it is a bit of a guess either way.

> I'm not sure about the SI conversion of the semitractor-trailer units.

Are we talking Arizona trailers, normal NA trailers or international-compliant sizes to begin with?

[0] https://www.space.com/spacex-rocket-crashing-into-moon-crate... [1] https://www.livescience.com/spacex-rocket-to-hit-moon

5040 knots, aka nautical miles per hour.

Because if you are using miles, use the only ones that matter (in aerospace).

to put that in perspective, that's 4.5 sunradii per fortnight, or .55 AU/year

Too bad it’s not headed to Purim’s location. Just sayin’

It'll be a few days early for Purim

Purim is March 17 this year, the President of Ukraine is Jewish, and celebrates it.

> Purim is March 17 this year

That's also St Patrick's day. It's going to be quite the drinking day for the intersecting demographic.

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