I searched and didn’t see a dedicated thread to this on the SDMB already, so here goes…
So, NASA’s DART mission appears to have been a smashing (heh) success-- the vending machine-sized satellite hit the smallish asteroid Dimorphos dead-center. My understanding is that it will take a couple months before enough data is gathered to know exactly how much its course has been altered, but it’s expected to be approximately a 1% change in trajectory overall.
In terms of being able to ultimately divert a future asteroid large enough to cause an extinction level event on a direct collision course with Earth, was this a ‘baby step’ toward that goal, or is this a pretty big deal, in the sense of “we’re ready for The Big One”? I’ve read that even though Dimorphos is just a fairly small asteroid, it would cause some pretty bad damage if an asteroid of its size hit Earth-- potentially taking out a city the size of New York and causing damage for thousands of miles in every direction. But it wouldn’t wipe out humanity, or all life on the planet.
I doubt there’s a definitive factual answer for this so IMHO it goes…
(BTW, I googled “nasa dart mission” and stumbled across a fun Easter egg-- when I started scrolling down, the info suddenly canted at a slight angle. At first I was like “WTF?!?”, then started laughing)
That’s a fun Easter egg. On my desktop screen a little spaceflight flues across, hits a picture and then the screen tilts.
As for your question, I think it’s a good small step. The really impressive thing to me is that the spacecraft guided itself into the asteroid, using AI to find the target.
It’s a baby step to collect initial data for future study. We should also practice landing payloads the size of a nuke onto an asteroid. Placing a couple of nukes on a extinction level asteroid while it is still far enough out and you could use them to redirect its trajectory. Right now it’s still science fiction, we need to prove out the methods now so we can use it if necessary in the future.
I had already been scrolling down when that happened, so I didn’t see the DART spacecraft hit the picture the first time- I thought starting to scroll triggered the tilt.
In any case we are most likely going to need to have prior experience in landing multiple large components safely onto an asteroids surface and secure it. No need to send actual nukes until we had to, test could be performed with other items. Just placing a nuke on the surface would be crude, ideally we would want to create some sort of crater to act as a barrel so that it could direct the energy effectively like a rocket nozzle. Even a solar sail would somehow have to be secured to the surface. We may even come up with several possible solutions depending upon the size of the object.
Nukes in the actual asteroid seem unnecessary, if you really need the nukes to get the necessary delta-v may be a better option would an Orion version of DART, if you catch my meaning.
The example above was to shade the asteroid to change it’s velocity. It seems to me that would take quite a while to change the velocity, just as would attached solar sails. Of course, the further away from Earth an asteroid is, the smaller change in velocity would change it’s path.
I could see at some point we could track a good part of the solar system the same way we track satellites in orbit around earth. We could very well develop the technology to track threats years or decades in advance of them being getting close enough to earth to require throwing the kitchen sink at them.
ISTM that the big technical challenge for protecting the planet from asteroids is detection, not deflection. If we detect them all early enough, then we can deflect them all early enough. We could send hundreds or probably thousands of missions equivalent to DART without significantly straining humanity’s resources.
As I understand it, it’s more important to catch them well before they get close to a gravitational keyhole that might send it on a collision course with Earth. If we can make it miss the keyhole, it will miss Earth, guaranteed.
Follow up-- it was reported yesterday that the DART spacecraft collision reduced the orbit time of the asteroid Dimorphos by 32 minutes! A successful mission would have been considered anything more than a 73 second reduction, and 10-15 minutes at most was expected.
I don’t understand why the error bars were so high. You know exactly how fast and how big the spacecraft is, and you should know pretty darn well the exact orbits of the asteroids or else you wouldn’t be able to hit them. The only open question I can think of is how heavy the asteroids are, and that shouldn’t differ from what is expected by more than an order of magnitude.
I was wondering this as well. I’m far from an expert on physics, but I would have thought that if you have a spacecraft of (X) known mass and velocity smashing into an asteroid of (Y) estimated mass, it seems like you should have had a pretty good idea of how much the orbit will change.
As you say, the mass was probably not known for certain, so that’s a variable. Maybe another variable was that they weren’t sure how direct a hit they were going to be able to achieve, and were able to hit the asteroid pretty much dead center. When they saw that they had a direct hit, they may have known they were going to get a significant course correction, but weren’t going to announce that until they had direct evidence.
ISTM that there would be a myriad of factors that NASA couldn’t know – not just the exact density of the asteroid, but the density variation – if it’s denser at one end, then that could affect how the impact nudges it. Also, how elastic the materials are, and the exact point of impact. That seems like it could add up to a lot of error.
I don’t think density could be off by an order of magnitude given what they already know about it. And given that it is a self-contained system, the elasticity and point of impact shouldn’t matter. I guess if it was a pile of rubble and it got hit sideways, some of the momentum could have been transferred to the ejecta instead of the main asteroid. (If it got hit head on, I would think, but could be mistaken, that if anything any unexpected ejecta should add to the speed difference rather than subtract because they’d be sent backward).
