Assessing Asteroid Threat

Makarand writes "According to a proposal submitted to the European Space Agency a fleet of five mini-probes should be sent each targeting an asteroid considered potentially dangerous. The mission objective will be to learn more about dangerous near earth objects so that we can plan how best to respond when under threat. Once in space, the probes would use ion propulsion engines that provide thrust by shooting out a stream of electrically charged particles. Power for the ion engines would be provided by ultra-lightweight solar arrays. Each probe will carry instrumentation to learn about the physical and chemical make-up of the target. The mission would cost around $150 mil which is quite low according to space mission standards."

Comments

A gamble for 10 billion...

[little1973]

That is the raw translation of a hungarian novel written in the early 80's.

It takes place in the near future when the Earth population is 10 billion. An asteroid threatens Earth, but so big nothing can be done just one thing. By calculating the trajectory of the asteriod the engineers notice that it nearly collide another, but smaller asteroid.

So, they send up a spaceship with full of explosives and ram it into the small asteroid in order to give it a push which is sufficient to make it collide with the big one.

Billiard on the cosmic scale. And it was written well before the public became aware of the asteriod threat.

what characteristics?

[fermion]

The article is quite short on details of exactly what threat characteristics we are to catalog. My understanding is that the two most important characteristics that threaten us is that the object has mass and will likely collide with earth. Both of these can be estimated quite well in enough without a mission to the object. Any characteristics beyond that, be it shape or chemical composition, does not seem to be so critical.

Now, one might argue that if we knew things like chemical make up or density or the like we might know how to destroy the object or perhaps could change it's trajectory with engines or a tractor beam or something. However, this implies that we know the object exists with enough advance notice to do something. To plan a research encounter, that might be a year. To plan a destructive encounter, I think that might be a month. I seem to remember that the in the last near miss, we did not detect the object until after it had passed.

Which is to say that we need better detection technology coupled with serious research of how to change trajectory. I do not believe converting a single projectile into hundred of projectiles is a reasonable solution. And of course, if we don't know the object is coming, there is nothing we can do

A lot of negativism

[panurge]

A lot of the arguments so far seem to be of the "why give up smoking, I might fall under a bus" variety. From the same people that continue to buy SUVs?

Considering the amount of money spent on practising for war every year - "defense", the proposal to the EU is peanuts. It is a proposal to start investigating the possibilities of a very real threat. I seem to recall the Siberian meteor impact as estimated as equivalent to about a 30MT H-bomb, and we were very lucky it hit where it did. It also seems that satellite photography is identifying more and more impact sites on the Earth. When I was a kid very few of these were recognised, and it seems reasonable to me that if we are learning that the frequency of such hits is much higher than expected, we should start to do something.
It's also worth remembering that the big impact on Jupiter occurred only a few years ago, and that very visible impact may well have concentrated people's minds. As telescopes get better, astronomers are realising there is far more debris out there than anybody knew- the old idea of 9 tidy planets and an asteroid belt has turned into a solar system full of all kinds of junk, moonlets, comet formation belts- the Solar System seems to be more like Mexico City than Singapore, if you see what I mean.
A billion dollars sound like a lot, but how much is the ABM system going to cost?

Dealing with a hard rock or a dirty snowball could need very different approaches (gentle push versus big bang?). Just because a multi-mile wide asteroid could be undeflectable and fatal, doesn;t mean that the real threat might come from a thing 100M across - obviously deflectable with the right technology, but nuking it could result in thousands of destructive small impacts.

To sum up this ramble:

• Destructive meteor impacts do occur on Earth
• Some of them are potentially preventable
• The cost of research is probably going to be far less than the US is going to spend developing nuclear warheads this year
• The cost of stopping a small asteroid could be a lot less than the estimated budget for stopping Saddam Hussein
• All in all, it looks far from a waste of EU money.

Thank you for reading this far.

Re:Solution looking for a problem

[jafac]

No, I think an ICBM would just about do the trick too, take off the warhead, and your payload becomes the third stage, get the third stage out of LEO using about half it's fuel (very rough assumption, expecially since we also would have had to fit it with appropriate guidance and maneuvering systems), land the 3rd stage ass-end-up on the asteroid, and fire the remaining fuel.

ICBM doesn't necessarily mean "nuke".

FYI - Mercury's Redstone, Gemini's Titan, etc. were formerly Ballistic Missiles - adapted for use in manned spaceflight - FYI.2; Titans are still one of the premier spacelauch vehicles in use today, and many are actual decomissioned ICBMs. (they're pretty useless as ICBMs compared to Minuteman or Peacekeeper, because Titans are liquid fueled) - but even so, I think a Peacekeeper would make an excellent asteroid-shover in a pinch, but I'm not sure exactly how much of the third stage would be left for asteroid-shoving if one just removed the warheads and fitted it with guidance/maneuver equipment. Maybe with some strap-ons?

Now, we all KNOW that an ION engine would be better for this application, because you get your energy from solar radiation (or nuclear power), instead of burning your propellant and oxidizer, plus, you get to apply thrust over a much longer period of time, with much finer control. But on the other hand, we've had exactly ONE successful use of ION engines. It's a worthy wheel to reinvent, but that doesn't mean we shouldn't get something rolling more quickly than development of an ION-based asteroid-shover would take. Then do ION-based technology later. In any case, we definately have adequate technology to get such a device positioned. Much of it sitting unused, waiting around for armageddon. If an asteroid strikes our world and ends all life because we were saving our launch capability (idle ICBMs) for a massive nuclear strike, we'll even be jilted of that.