Orf Topic as they say.

[Sysadmin]

Wednesday, November 24

The second mission of the week is the launch of the DART probe that was mentioned at the top of the article. A SpaceX Falcon 9 rocket will carry the probe out of Earth?s gravity before it sets a course for asteroid

65803 Didymos. The asteroid is a binary asteroid which means it has a satellite orbiting it ? this satellite is known as Dimorphos and will be DART?s impact target. As things stand, the impact is due to take place on September 30, 2022, but variables cause the schedule to shift.

The DART mission doesn?t carry any scientific payloads, just a camera called DRACO which will help to target the Didymos system. An interesting aspect of this mission is the inclusion of the NEXT-C ion engine. Compared to other ion engines, NEXT-C is described as having improved performance, thrust, and fuel efficiency. Though not the primary propulsion system on DART, NEXT-C will demonstrate its potential for use in other deep-space missions. This mission will launch at 6:20 a.m. UTC and will be available from NASA?s and SpaceX?s live streams on their websites.

The Double Asteroid Redirection Test (DART), @NASA's first #planetarydefense test mission, will impact an #asteroid to demonstrate a technique that could be used in the future to protect Earth from a potential impact.

Learn more in this new @JHUAPL video! https://t.co/Yk6ic5ncyg 

[williamwright]

How do they know there isn't life on that asteroid?

Bill

[Tim Streater]

They're not hitting the asteroid.

[Paul]

If there is, we'll "take care of it".

All those years of practice at the arcade, are not going to be wasted. Pew! Pew!

I really wonder what will happen, when Dimorphos splits in two. Will they send two rockets, with a bullet each, to split those in half ? What should our strategy be ? Should we pivot our ship, and then take careful aim ? Etc.

Paul

[williamwright]

They're hitting an asteroid that is one of two asteroids that orbit each other.

Bill

[Brian Gaff (Sofa]

I doubt very much if there is life there, since the whole asteroid belt is one continuous shooting gallery without our help, but waiting around for a rock to hit it is a bit difficult, so they will take their own 'rock' with them!

Its not the first time impactors have been sent to asteroids. at least two other missions have done this in order to reveal sub surface material. Brian

[Tim Streater]

Yes, they are hitting the satellite, not the asteroid. And they are hitting a

170 metre rock with a craft weighing, what, one ton? No chance of splitting that.

The idea is to slightly change its orbit around Didymos and see what the effect is.

[Martin Brown]

The theme tune to "Red Dwarf" answers that perfectly well.

It's cold outside Theres no kind of atmosphere I'm all alone, more or less Let me fly far away from here?

[Paul]

More info here. Some simulations included.

Paul

[Tim Streater]

Thanks - that's interesting. I see that modelling what's gonna happen depends on some serious unknowns.

[pinnerite]

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The New Scientist had an article in recent weeks about space debris about to ruin our lives before global warming or grey goo get us.

So where is this collision scheduled to take place?

Outside the lagrange point I hope. The local one that is.

Alan

[Tim Streater]

The asteroid is not at a Lagrange point.

[williamwright]

It's much like climate prediction then.

Bill

[Andrew]

Is that known unknowns, or unknown unknowns (like Covid-19)

[Tim Streater]

I'd say it's all the former (even covid was a known unknown - we knew there'd be a pandemic sometime without knowing what form it would take). In this case the form of the surface (solid or rubble pile) will have an effect on the reaction to the impact.

[whisky-dave]

But those unknown unknowns are known, they have been known for a few hundred years like the plague , spanish flu, asian flu, and others that come around every so often like asteriods and hemorrhoids....

[Tim Streater]

Seems the impactor (now launched) weighs some 500kg (around 0.5 tons). Meanwhile the satellite it will hit weighs around 5 million tons and the asteroid itself around 500 million tons.

They estimate the speed reduction of the satellite as around 0.4mm/sec, which doesn't sound much but adds up over time.