The DART mission to nudge an asteroid

Funkworks

Low Earth Orbit, obstructing Earth's view of Venus
Joined
Jul 28, 2018
Messages
4,688
Reaction score
5,359
The DART mission has taken off. Its goal is to target an asteroid, crash into it, and make it deviate from its present course.

 

boomtube-mk2

Well-Known Member
Joined
Sep 6, 2014
Messages
2,290
Reaction score
2,020
Whatever happened to LUCY?
The last I read about it one of the solar panels had problem fully deploying.

Couldn't we just cajole the asteroid into not hitting Earth?
"Come on Dimorphos, you don't really want to collide with Earth; what would all the other asteroids think?"
 

dr wogz

Fly caster
Joined
Feb 5, 2009
Messages
8,890
Reaction score
4,845
Location
Land of Poutine!
Does anyone else have the feeling that someone isn't being completely straight with us about this mission?
what do you think the mission is really all about?

Not being rude or trolling.. But am genuinely curious as to what you might think this is about.. Mining? crossed my mind as well.. Planned 'touchdown' on a moving target? also thought of that.. to add a remote device to an asteroid: to weaponize it / make it controllable / make it capable of hitting a specified target?! also thought of that.. :D
 

Funkworks

Low Earth Orbit, obstructing Earth's view of Venus
Joined
Jul 28, 2018
Messages
4,688
Reaction score
5,359
If they could get some High-Def. video of the impact, that would be cool.

From today' wikipedia:
"It is accompanied by an Italian Space Agency (ASI) 6-Unit LICIACube flyby Cubesat that will be released 10 days before impact to observe the asteroid and Dart's impact."

On the LICIACube page:
"it plans to take a image every 6 seconds during the DART's impact period

News story:
 

Blast it Tom!

Well-Known Dweeb
TRF Supporter
Joined
Dec 29, 2019
Messages
1,971
Reaction score
1,783
Location
Pittsburgh
Knock a train off the track with a BB gun
That's what I'm thinking; I can't imagine that they'll be attempting to do anything like bust it up, and it's tough to imagine a measurable "nudge" - maybe if they impact perpendicular to the path? But I have yet to read up on mission specifics. Mass x velocity squared can represent a lot of energy at interplanetary speeds, but how would it be distributed? What is the mass of the target asteroid? Recall the Osiris-Rex mission to sample an asteroid, the approach speed was very, very slow as the gravity was so slight - but it was still an awfully big chunk of rock to imagine changing it's path with an earth-launched directed energy source - especially if they're only counting on impact energy.
 
Last edited:

OverTheTop

Well-Known Member
TRF Supporter
Joined
Jul 9, 2007
Messages
8,021
Reaction score
6,321
Location
Melbourne Australia
I am reading a book currently that discusses a lot of detail about redirect missions for planetary protection. Move it early enough and a small deflection is sufficient. If you are trying to move it to prevent a harmonic return on future orbits it can be sufficient to keep it out of "keyhole" zones which might only require a deflection of a couple of hundred meters or even less. You don't necessarily have to deflect it the width of a planet.

Also current modelling says you get about three times the kinetic deflection energy. The kinetic energy is only about 1/3 of the impulse provided, a plasma stream caused by the impact provides the rest. This mission will validate some of the modelling.
 
Last edited:

Joekeyo

Well-Known Member
TRF Supporter
Joined
Sep 12, 2019
Messages
766
Reaction score
716
Location
Sun City Center, FL
If NASA said that the mission was to find an alternative source of magnesium, we could find that more believable. Nevermind, they tried that already.
 
Last edited:

Funkworks

Low Earth Orbit, obstructing Earth's view of Venus
Joined
Jul 28, 2018
Messages
4,688
Reaction score
5,359
Found a bit of data.

Moon data

moon diam: 160 m
moon radius: 80 m
moon volume: 2,144,660 m3
moon density: 1.7 g/cm3
moon density: 1700 kg/m3
moon mass: 3,645,922,994 kg

Probe data

probe speed: 6.6 km/s
probe speed: 6,600 m/s
probe mass: 610 kg
probe momentum: 4,026,000 kg·m/s
probe energy: 13,285,800,000 J

In case anyone wants to calculate (maybe me later).

 
Last edited:

OverTheTop

Well-Known Member
TRF Supporter
Joined
Jul 9, 2007
Messages
8,021
Reaction score
6,321
Location
Melbourne Australia
They’re probably going for a side impact, which will make the moon deviate from its regular orbit.
Based on a quote from your last link (GSFC) I suspect they are going to hit it head-on, directly aiming for the CG (so no induced rotation). It looks like they are looking at the orbit relative to its companion and this makes sense as it it should be quite a sensitive tool to measure the changes. Measuring changes in the heliocentric orbit of the pair around the sun is more difficult and doesn't make sense. Remember it is the \( {\Delta}V \) in line with the orbit that raises or lowers the orbit. Pushing on the side just changes the eccentricity I think. They are going for a head-on slam and estimating a 1.4% decrease in orbital period (lowering of relative orbit).
 
Last edited:

ThirstyBarbarian

Well-Known Member
Joined
Feb 11, 2013
Messages
10,972
Reaction score
5,175
I saw something on this last night. The main asteroid has a small “moon” asteroid orbiting it. And the orbit of the moon around the main asteroid is known very precisely. So the impact of DART on the small moon asteroid is going to cause an extremely small change in the moon’s velocity. EXTREMELY small. I don’t recall exactly what he said, but a remember the words “about half a millimeter”, so maybe .5mm per second? Per hour? I don’t really know. But apparently it’s enough to cause a measurable change in the orbit of the moon around the main asteroid. This is just a demonstration project, so as long as the change is measurable, the experiment will provide data, even if there’s not a practical application at this scale.

The other thing the guy mentioned was that as a practical matter, if we want to save the earth from an asteroid impact, the best way would be to know years in advance and just deflect it a tiny bit. It really doesn’t need to be very much.
 

Funkworks

Low Earth Orbit, obstructing Earth's view of Venus
Joined
Jul 28, 2018
Messages
4,688
Reaction score
5,359
Based on a quote from your last link (GSFC) I suspect they are going to hit it head-on, directly aiming for the CG (so no induced rotation). It looks like they are looking at the orbit relative to its companion and this makes sense as it it should be quite a sensitive tool to measure the changes. Measuring changes in the heliocentric orbit of the pair around the sun is more difficult and doesn't make sense. Remember it is the \( {\Delta}V \) in line with the orbit that raises or lowers the orbit. Pushing on the side just changes the eccentricity I think. They are going for a head-on slam and estimating a 1.4% decrease in orbital period (lowering of relative orbit).

Ok thanks. And I edited my post. Sometimes my links are longer than I have time read on a lunch break 😁
 

cbwho

Well-Known Member
Joined
Mar 20, 2019
Messages
380
Reaction score
248
Location
MN
This is perhaps one of the most important NASA missions. It's a shame nowadays that people (rocketeers especially) don't understand the importance of staving off the next big asteroid strike...
 

OverTheTop

Well-Known Member
TRF Supporter
Joined
Jul 9, 2007
Messages
8,021
Reaction score
6,321
Location
Melbourne Australia

aerostadt

Well-Known Member
TRF Supporter
Joined
Oct 26, 2009
Messages
4,082
Reaction score
781
Location
Brigham City, UT
One of the reasons MRV and MIRV on ICBM's are so practical is that once the payload is out of the earth's atmosphere the bus that is carrying all the warheads can make minor adjustments sending the warheads on vastly different trajectories. (Such is the insanity of warfare finding technical solutions to engineering problems. Once they are up who cares where they come down that is not my department says Wernher von Braun, or so went a comedian's line. Bottom line, give engineers good jobs to do real work.)
 

OverTheTop

Well-Known Member
TRF Supporter
Joined
Jul 9, 2007
Messages
8,021
Reaction score
6,321
Location
Melbourne Australia
I can't imagine that they'll be attempting to do anything like bust it up,
Breaking up an asteriod is problematic in that unless you give it enough energy to ensure all the pieces have sufficient escape velocity to get away from each other then they all just stay in the same neighbourhood and you don't get a second shot at the problem. That is one of the things that limits using nukes. If the asteroid is rocky a nuke has a chance of splitting it. Ok to use them on metallic asteriods, but the issue there is timing. They estimate that it is most effective to detonate the explosion at about 70m altitude. The problem is that the closing speeds for these missions is in the range of 20-30km per second. Timing is critical for maximum effectiveness.
 

Michael L

Random Pixel Generator
TRF Supporter
Joined
Sep 21, 2020
Messages
669
Reaction score
567
Location
Weimar, TX
Breaking up an asteriod is problematic in that unless you give it enough energy to ensure all the pieces have sufficient escape velocity to get away from each other then they all just stay in the same neighbourhood and you don't get a second shot at the problem.

The Russians just proved that with a satellite. Trash everywhere.

staving off the next big asteroid strike...

I'm not sure how important it is but I'm all for trying as long as we don't splatter the planet with the detritus. Hand grenades were invented for a reason and the are effective.
 

Funkworks

Low Earth Orbit, obstructing Earth's view of Venus
Joined
Jul 28, 2018
Messages
4,688
Reaction score
5,359
... they all just stay in the same neighbourhood and you don't get a second shot at the problem...

I haven't digged into this very much, but many small pieces still seem better than a big one. By coming in smaller, the pieces would come in at different times and places, spreading overall friction heat over a larger area, and more mass would burn up. It all depends on size and speed of course. A diameter of 160 m or 500 ft is apparently when it starts to be a concern. Not sure how fast a typical meteorite goes.
 

Latest posts

Top