New research explores asteroid deflection using spacecraft to crash into body at high speeds

February 17, 2016
An artist's illustration of asteroids, or near-Earth objects. Credit: ESA - P.Carril

Asteroids headed for a collision with the Earth, if found early enough, can be acted upon to prevent the potentially devastating consequences of an impact. One technique to divert an asteroid, called kinetic impact, uses a spacecraft to crash into the body at high speeds.

This approach delivers the momentum of the spacecraft, while also providing an additional boost of momentum through the production of crater ejecta exceeding the asteroid's escape velocity. Researchers at Lawrence Livermore National Laboratory (LLNL) have been studying the effectiveness of the kinetic-impactor strategy by carrying out 3D simulations of the process.

In a new paper published in Icarus (link is external), LLNL planetary defense researchers find that by kinetic impact is sensitive to a range of asteroid characteristics, including strength, porosity, rotation and shape. These and other asteroid properties may not be well constrained before an actual mission is staged, leading to variability in the deflection outcome. By simulating a range of initial conditions for the target asteroids, researchers were able to quantify, for example, how greater target strength decreases the delivered momentum impulse and how, for an asteroid of constant size, added porosity can result in more effective deflections, despite the dampening of the shock waves produced during an impact.

In this model, asteroid Golevka (approximately 500 meters across) is impacted by a 10,000 kilogram mass traveling at 10 kilometers per second along a principal axis of the asteroid. Colors denote the accumulation of damage. The final change in asteroid velocity for this example is approximately 1 millimeter per second.

In this model, asteroid Golevka (approximately 500 meters across) is impacted by a 10,000 kilogram mass traveling at 10 kilometers per second along a principal axis of the asteroid. Colors denote the accumulation of damage. The final change in asteroid velocity for this example is approximately 1 millimeter per second.

The kinetic-impact approach is one of the most mature technologies for deflecting a hazardous asteroid. For cases where the warning time is known well in advance and the asteroid is not too large, it is the preferred deflection mechanism, as described in a 2010 National Research Council report (link is external).

"Asteroids are naturally diverse, and researchers have little direct information about their mechanical properties," said Megan Bruck Syal, lead author on the paper. "This study emphasizes the important role of characterization research, which is needed to constrain the different types of conditions that could be encountered at potential deflection targets."

These results provide new information on the range of possible responses to a kinetic deflection attempt, which can directly inform the design of future kinetic-impact missions. The simulation results also are potentially useful for the interpretation of results from rare, full-scale impact tests, such as the Asteroid Impact and Deflection Assessment mission's planned impact of the Didymos secondary in 2022.

Explore further: New map shows frequency of small asteroid impacts, provides clues on larger asteroid population

More information: Megan Bruck Syal et al. Deflection by kinetic impact: Sensitivity to asteroid properties, Icarus (2016). DOI: 10.1016/j.icarus.2016.01.010

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antialias_physorg
5 / 5 (4) Feb 17, 2016
sensitive to a range of asteroid characteristics, including strength, porosity, rotation and shape.

So how about we shoot the deflector past the asteroid dragging a net. When the asteroid catches the net the deflector is whipped around and detached when it is deflected by 90° from its original path.

This may be a method that is less sensitive to porosity, rotation and shape.

Making the net sturdy enough to not get ripped apart by the strain and getting it to stick to the asteroid may be quite a trick, though.
daqddyo
5 / 5 (2) Feb 17, 2016
"These and other asteroid properties may not be well constrained before an actual deflection mission is staged, leading to variability in the deflection outcome."

like hitting the Earth during this orbit or during future asteroid orbits?
marko
1 / 5 (1) Feb 17, 2016
Another way to deflect the asteroid is to use retrorockets to blow back at the asteroid.

The rocket exhaust would react against the asteroid from some distance away, so the exhaust pressure would eventually strike the asteroid surface with less intensity than a full-on direct impact.

Potentially the 'impactor' could be fired toward the asteroid at even higher speeds than a direct strike model, because the retrorocket would then be able to use more delta V in braking to indirectly push against the asteroid.

The 'impactor' could conceiveably use excess rocket thrust to move directly away from the asteroid as well until all the fuel is expended.

Also more than one puffer rocket could be used together or in series, instead of the big bang method which could shatter the asteroid into many unmanageable pieces.
antialias_physorg
5 / 5 (6) Feb 17, 2016
retrorockets

That might be tricky, because you
a) need to have your craft stationary relative to the asteroid (something an impactor most decidedly does not want to do). This requires a lot of fuel
b) need to spend the same amount of fuel you are blasting at the rock in the opposite direction (or you'll just end up sending your retrorocket-craft off into space)
TheGhostofOtto1923
3.7 / 5 (3) Feb 17, 2016
dragging a net
Antialias needs to consider that if he thinks of something, experts have most likely thought of it first.

"One presentation, by Harold Gerrish of NASA's Marshall Space Flight Center, shares a heritage with space shuttle tethered-satellite missions flown in 1992 and 1996. Tethers Unlimited, of Bothell, Wash., proposed the use of free-flying CubeSats to deploy nets and tethers for capture and control after the primary spacecraft rendezvous with the asteroid target...

"Northrop Grumman offered another strategy in which a capture craft is equipped with sensors, guidance and propulsion to characterize and match the motion of the target before deploying two clamshell-like AstroMesh capture panels. After enclosing the asteroid, internal webbing would secure it for the lunar leg of the mission..."
gkam
1 / 5 (4) Feb 17, 2016
Cut-and-paste.

Real experience.
antialias_physorg
5 / 5 (5) Feb 17, 2016
Antialias needs to consider that if he thinks of something, experts have most likely thought of it first.

Gee..don'tcha think I'm aware of these?

I was thinking of the combination of a massive slug and a net...not a controlled net/thruster approach.
TheGhostofOtto1923
3 / 5 (2) Feb 17, 2016
Antialias needs to consider that if he thinks of something, experts have most likely thought of it first.

Gee..don'tcha think I'm aware of these?

I was thinking of the combination of a massive slug and a net...not a controlled net/thruster approach.
Oh you mean something like this?

"The plan is to attach a gigantic weight to an Earth-bound asteroid using an enormous cord. This crazy-sounding contraption would change the asteroid's center of mass and subsequently its trajectory, averting a potentially catastrophic scenario...

"Aerospace engr Major David French of the Air Force Research Labs [EXPERT] mathematically modeled how different weights and lengths of tether would affect a killer asteroid's orbit over time. The results are in the Dec issue of Acta Astronautica.

He found that, in general, longer tethers and larger masses would more significantly change the asteroid's orbit. The alteration would occur slowly, taking anywhere from 10 to 50 years."
TheGhostofOtto1923
3.7 / 5 (3) Feb 17, 2016
Further

"This tether-deflection idea is an interesting intellectual exercise," said astronomer David Morrison of the Asteroid and Comet Impact Hazards Group at NASA's Ames Research Center. "But it is of no practical value."

Morrison points out that putting enormous objects, such as a heavy tether and ballast, in space is far beyond the entire human race's launch capability. Furthermore, the cost of designing and building a strong enough rope makes the solution intractable.

"From a practical point of view, the technique is a mess," agreed Russell Schweickart, former Apollo astronaut... Schweickart and Morrison offer a much simpler idea that uses current technology: Change the asteroid's orbit by crashing something into it. Even a relatively small satellite would alter the orbit enough to stave off certain doom..."

-No sense trying to reinvent the wheel, oder?
Hat1208
5 / 5 (4) Feb 17, 2016
Why would you crash into the object instead of landing on it and using the remaining fuel to move the object with no threat of it breaking into smaller projectiles? Anyone.
gkam
1 / 5 (2) Feb 17, 2016
I agree.
Uncle Ira
5 / 5 (6) Feb 17, 2016
Why would you crash into the object instead of landing on it and using the remaining fuel to move the object with no threat of it breaking into smaller projectiles? Anyone.


This is only a guess because I am not the scientist-Skippy. Maybe the crash method will transfer more momentum with the impact and alter the course more than just using up what little fuels might be left over after the trip?
Hat1208
5 / 5 (7) Feb 17, 2016
@Uncle Ira

I would also guess that the distance that the asteroid is encountered would be of some importance.
Steelwolf
not rated yet Feb 17, 2016
If there is going to me a 'Mission' to do such a thing, there should be set up something like a large Solar Sail of Mylar and with proper adjustments of size of sail to create different thrust values so that it could be nudged into, say a Lunar orbit so that the asteroid can be mined. If it is going to come close to us anyways, we may as well slow it down enough to join our gravitational well and then we can mine said asteroid at our leisure instead of worrying about an impact. If you are going to waste 10kg of vehicle and the propellant to get it up to that velocity, one may as well do either a well built robotic assembly or a manned mission that can be on hand WHEN things Go Wrong to be on hand to make adjustments and even start prospecting the asteroid. So much more profit in capture than just deflection. Besides, deflected can still come back at us much, much later.
Uncle Ira
4.4 / 5 (7) Feb 17, 2016
@Uncle Ira

I would also guess that the distance that the asteroid is encountered would be of some importance.


Yeah, a little bump a long way off would do more than a big crash closer up.

But I will tell you one thing true. I am glad the scientist-Skippys are working on it. But if one comes around, I hope they will keep it to them selfs until they get through saving us. If one was going to hit us, there is not much I could do to help, and it would really ruin what time I have left. Telling me so I can worry about it I mean.
Jayded
5 / 5 (1) Feb 18, 2016
If the objective is to deliver the momentum of the spacecraft to the asteroid in an attempt to alter course, then surely it would be easier to build heavy missiles with space capability. They could be launched faster, act in a closer range if need be and deliver the momentum impact rapidly. Would also cost ALOT less then ramming a spacecraft into an asteroid and you would have more than one shot at achieving the deflection.
Captain Stumpy
5 / 5 (4) Feb 18, 2016
But if one comes around, I hope they will keep it to them selfs until they get through saving us
@Ira
yeah,,, the panic would be crazy if it were announced... and it if failed, it would only escalate

it would be a great reason for a h*ll of a party though!

.

Besides, deflected can still come back at us much, much later.
@Steel
yeah... but with every attempt we learn more and more, so it would be easier to accomplish as we progressed

of course, it also stands to reason that we are going to be hit regardless (eventually) so the thinking that it can still come back to hit us is moot

something WILL come to hit us... tis far better to be prepared and to do something than sit there and do nothing, eh?

.

build heavy missiles with space capability
@Jayded
which is a spacecraft, isnt it?
i don't think they mean a rover, shuttle or Apollo craft in use unless it's an emergency

Space billiards (LOL)
antialias_physorg
5 / 5 (7) Feb 18, 2016
Why would you crash into the object instead of landing on it and using the remaining fuel to move the object

1) You need to match velocity with an asteroid in order to land. This takes a LOT of fuel. Fuel is the thing that imparts the energy. It is better to spend that fuel accelerating an impactor than to spend it doing nothing to the asteroid.
2) Landing is tricky business (see Philae) . It may even be impossible if the asteroid is rotating quickly. If there's a rotating asteroid approaching you'd need a backup plan (impactor?). It's better to have a one-size-fits-all solution than to develop several solutions in parallel (Going for several systems tailored to different types of asteroids is something we can afford once we have the first system down pat)
bluehigh
1 / 5 (4) Feb 18, 2016
Gee..don'tcha think I'm aware of these? - Anti-Thinking


Probably not, you looked it up on Wikipedia and squawked like a parrot. Fell back in your rocking chair and dribbled.

Aside from feeding crackers to the senile this article and thread was simply, um, dumb.

bluehigh
1 / 5 (2) Feb 18, 2016
it would be a great reason for a h*ll of a party though! - The Captain


At least someone has sensible priorities, however you might want to find another reason.

There's no likely impact in the forseeable future.
antialias_physorg
5 / 5 (4) Feb 18, 2016
If there is going to me a 'Mission' to do such a thing, there should be set up something like a large Solar Sail of Mylar and with proper adjustments of size of sail to create different thrust values so that it could be nudged into, say a Lunar orbit

To nudge it into a lunar orbit you would have to slow it down considerably (the average relative speed of a close encounter of this kind is 70km/s ). This takes either a huge amount of fuel or a solar sail that has been attached VERY far out.

The problem with the "very far" is that there is a size above which asteroids are really dangerous. Unfortunately that size is small enough so that we cannot detect asteroids around that size limits very far out. So we need a short term deployable/effective system (i.e. several days to several weeks). Solar sails are more on the order of several months/years until they impart enough momentum to make a difference.
FainAvis
5 / 5 (4) Feb 20, 2016

There's no likely impact in the forseeable future.


We all missed the Chelyabinsk thingo, and there have been a few where we only got the back number plate.
Whydening Gyre
5 / 5 (2) Feb 20, 2016
sensitive to a range of asteroid characteristics, including strength, porosity, rotation and shape.

So how about we shoot the deflector past the asteroid dragging a net. When the asteroid catches the net the deflector is whipped around and detached when it is deflected by 90° from its original path.

This may be a method that is less sensitive to porosity, rotation and shape.

Making the net sturdy enough to not get ripped apart by the strain and getting it to stick to the asteroid may be quite a trick, though.

The logistics of getting a net that "heavy" out to an asteroid would prob'ly be quite prohibitive given todays technology...
And once you get the net around it - its still on the same trajectory, no?
Whydening Gyre
5 / 5 (3) Feb 20, 2016
Aside from feeding crackers to the senile this article and thread was simply, um, dumb.

But they're the Triscuit with olive oil, cracked black pepper and thyme ones... and I am kinda hungry...

AA,
Saw your second comment about a weight and a tether attached to the net - would make it even MORE logistically prohibitive, no...?
Whydening Gyre
not rated yet Feb 22, 2016
Here's a thought...
Why not pick a smaller asteroid in a Lagrangian area of the asteroid belt, strap an acceleration device to it, bring it to an Earth Langrange point and keep it on standby for use as necessary?
A well timed, glancing blow to an incoming threat surely would change the incoming trajectory, no?

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