"The DART spacecraft changed the orbital period of Dimorphos by a whopping 32 minutes"

[Talitha]

More here (Wed Oct 12th 2022)

[OAITW r.2.0]

1. That's pretty damn good, but what does this mean?

Did the asteroid move greater than 1 Earth radius? Over time and distance,

[brush]

2. Does that mean it shifted it's path by degrees...

which would make it miss Earth if it was headed towards us?

[Bernardo de La Paz]

4. No. It is in orbit around a second asteroid. A real problem asteroid would get more mass

The technique has been proven, now.

If there was a real problem asteroid in our future, it would be given a much more massive hit. And perhaps multiple hits.

The mass of the impacter was 570 kg (1260 pounds for provincials). It would not be difficult to assemble in a few months a fleet of say a dozen boosters and their impacters massing say 10,000 kg each (22,000 pounds). 120,000 kg / 570 kg = 210 times the mass.

Plus, you can by choosing timing and orbital insertions and gravity boosts you can gain velocity and hence momentum at impact.

Plus,

The other big thing is that the farther ahead you can determine the need, the bigger end effect a nudge has. So in principle if you detect it far enough ahead, you could impact it with a feather at a walk and it be enough. That is effectively impossible because computing the orbits is a "multi-body problem" where computing even three bodies can be a challenge.

So, is it enough mass? Not this one perhaps, given anticipated forecasting and sizes involved, but something like it is enough mass. Search and forecasting are improving too.

[brush]

5. Did the hit alter/change the orbit of the smaller asteroid...

around the larger one? Just trying to understand what was accomplished.

[Bernardo de La Paz]

6. Yup, you got it. . . . nt

[PSPS]

3. I guess that qualifies as a success

32 minutes is about 1/2 degree. They would have considered a 73 second change (about 0.02 degree) a success so this accomplished about 25 times the deviation desired. Whether this would be "enough" would depend on the distance from Earth, of course. And then there are other considerations. Would the deviation send it into the influence of other bodies with unpredictable/undesirable results? I'm pretty sure they can calculate that. As John Glenn said, "Get the girl, check the numbers."

[muriel_volestrangler]

7. No, this is minutes of time (for the period of the orbit around the larger asteroid), not angle

The observed decreases in relative brightness for each night’s dataset correspond to Dimorphos eclipses from a new orbital period of 11 hours and 23 minutes – demonstrating that the eclipse timing differs from pre-impact period of 11 hours and 55 minutes.

https://www.nasa.gov/feature/nasa-dart-imagery-shows-changed-orbit-of-target-asteroid

An orbit with a shorter period has less energy (eg it needs less energy to send a satellite into a low orbit around Earth that takes around 100 minutes, than to put it into a geostationary orbit that takes 24 hours). So they know that they took a significant amount of kinetic energy out of this asteroid by hitting it 'head on'. If they can work out its mass accurately (which such a close-up view may help with), they will know how much.