NASA finds crashing spacecraft into asteroids is a viable defence strategy Plumes of dust and rocks kicked up from the surface of asteroid Dimorphos after NASA's DART spacecraft smashed into it altered the space rock's orbit more than the kinetic impact alone, according to research published on Wednesday. Boffins successfully changed the position of an astronomical body in space for the first time in …
On the scale of energy used to create the asteroid in the first place, this was a light brushing with a feather. Besides, can you do violence to an inanimate object. We changed it, but I don't think we "damaged" it. It's just a rock that will float around in nothingness until it hits something.
Astronomers would have to spot the object in advance – "several years at a minimum, but preferably decades"
Yet also be able to measure its position and trajectory at vast distances with sufficient certainty to be *sure* it would impact Earth.
Otherwise, if you're unlucky, the deflector mission will cause it to hit the Earth when if left alone it would have missed!
In orbit of what? The Earth? The Sun? Both assume you would be able to adjust the flight path of the craft easily from being in a continuous, long-term stable orbit to heading (the right way) out into space, and that the craft can gain sufficient momentum (notably in the right direction!) from the available fuel it lofted on original launch (especially as gravity slingshots are likely to be unavailable)? For the timescales involved, it's probably just as easy to launch from Earth. That way it's also easier to prep the correct size/mass of the craft you need for the job. Or maybe the Moon or Mars are better (or additional) locations?
Loitering impactors could work but you're right, they need to be in an orbit that is easy to escape from. How about a big circuit between a gas giant and the sun (angled off the ecliptic so we don't accidentally bomb ourselves). Adjusting the vector on the long boring part of the orbit wouldn't require as much energy as escaping from a close orbit.
Another possibility is just sending up motors and guidance systems to the asteroid belt (or rings of Saturn) to bolt on to a lump of rock to add mass for a space based impactor.
But given the current state of rocket technology, the best bet would be to prep a few impactor frameworks on the ground and jut add whatever motors are available when it's needed.
“ How about a big circuit between a gas giant and the sun (angled off the ecliptic so we don't accidentally bomb ourselves).”
Big expensive (in delta-V terms) plane change[1] required to put the interceptor into an out of the ecliptic orbit and then another one to intercept an incoming threat which is most likely to be in (or close to) the ecliptic
[1] I don’t know much about orbital mechanics, but I *do* know that plane change is about the most energy intensive manoeuvre (short of actually putting something into orbit in the first place) you can do with a satellite…
"plane change is about the most energy intensive manoeuvre (short of actually putting something into orbit in the first place) you can do with a satellite…"
From the comments in another recent discussion somewhere online, I think plane changes can actually be more expensive (in terms of delta-v) than launch.
I heard on the radio that it was knocked out by 4x more than they expected. I'm surprised at this as I would have expected them to get it roughly correct knowing the velocity and mass of both objects? Perhaps they don't know the the mass of the asteroid? But 4x!?
It's not exactly brain surgery, though is it?
As it seems we can no longer rely on Bruce Willis to go up there and sort this out, bless him, we might need something like this to save humanity.
Other cheap aussie lagers are available, and I *think* this advert has aged well.
Ha ha ha. I'd forgotten that little quip. See? They even knew about it back then!
Did they take something for the ladies? Couple of bottles of sherry?
Perhaps they don't know the the mass of the asteroid? But 4x!?
That was addressed in El Reg's article. Besides the momentum transfer of DART's impactor, the plume of debris ejected by the impact had a stronger rocket-like effect than expected. It's hard to model the behavior of a milli-G pile of dust and gravel during a deep impact.
For a pile of dust & gravel just rely in the ejection impulse. Send up a solar-powered gizmo that parks itself on the asteroid scooping up handfuls & ejecting it. No need to achieve high velocities and wiith enough warning the entire asteroid could be thrown away. My H Robinson could design something suitable in a trice.
Wouldn't it be funny if the ESA and NASA both launched kinetic impactors* at the same existential threatening bit of space debris and they crash into each other over the object of interest? Maybe we can rather shield the earth by surrounding it with an orbiting, high velocity ring of asteroid deflecting metal fragments. Oh wait, construction has already started.
Anyway, remind us again why this smelly, polluted, over populated planet is worth saving while some little dictator man has his fingers on the nuclear weapons trigger ready to cause more damage than a HUGE comet or asteroid can ever do?
* FireFox spell checker suggests "imp actors" :rolling-eyes:
re kinetic "imp actors"
Was it not a rugby antic a few years ago to throw people of diminished growth as part of a drunken "frolic" ?
Ah yes:
https://www.theguardian.com/sport/blog/2011/sep/15/dwarf-throwing-england-rugby
Could that be what the Firefox spellchecker was alluding to ?
ESA and NASA work together very closely, so this would never happen anyway. In fact, ESA also supported NASA with DART:
ESA’s network of eyes on the sky, Estrack, is supporting NASA in the weeks before impact by tracking DART, helping to provide data on its status, location and velocity and crucially keeping a constant watch during its final 12 hours when a live stream of images will be pulsed home to be made available and watched ‘live’ by countless around the globe.
https://www.esa.int/Space_Safety/Planetary_Defence/ESA_deep_space_network_tracks_DART_asteroid_impact
Or we would quickly see conspiracy theories claiming that the mission is actually intended to knock it into Earth's orbit, or denying the science that says it will hit Earth, or saying we should let [the US | China] fund it alone because based on calculations of the exact time of impact and the direction of approach that's where it will most likely hit.
So, considering that the mass ejection produced more movement than expected, maybe we need to be careful how much mass from Earth we eject out beyond Earth's orbit.
Title: Just popped into my head. Searched it before posting and found it was the B side to "Point me at the Sky" strange coincidence.
Icon: Visual of mass ejection. Okay, mass conversion as well.
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2024
