The Discovery Enterprise: Animation of NASA's Proposed Asteroid Retrieval Mission

I agree there is a problem of keeping humans interested in Space. In this
instance capture of asteroids is being linked with the possibility that one
of these could damage local areas of the planet - a large one could put
paid to life on the planet itself.

Nasa's advice on asteroid hitting Earth: pray ...
http://www.telegraph.co.uk/science/space/9943048/Nasas-advice-on-asteroid-hitting-Earth-pray.html

*Washington (CNN)* -- The good news is that the chances an asteroid big
enough to destroy a continent or all of civilization will hit Earth this
year are only one in 20,000, a congressional panel learned Tuesday.

The bad news is the government needs to spend billions of dollars in coming
years for new technology to prevent such a possible catastrophe, regardless
of the low probability, experts told the House Science, Space and
Technology Committee.

"The odds are very small, but the potential consequences of such an event
are so large, it makes sense to take the risk seriously," contended John
Holdren, who directs President Barack Obama's Office of Science and
Technology Policy.

http://edition.cnn.com/2013/03/19/politics/congress-space-threats

... If the probability that a big one could 'destroy a continent or all of
civilization', is one in 20,000, it is something to worry about. I
remember, before Chernobyl the probability of a nuclear accident was put as
being less than one in a million.

Coming to the issue of capturing an asteroid; in the animation we see a
relatively small satellite capture a 500 ton asteroid. Evidently it would
have exhausted part of its fuel resource to align with the velocity of the
asteroid - I can only wonder how much fuel will be left to put the asteroid
in orbit around the moon. Clearly there is a need to develop new propulsion
technology which will make use of the material of the asteroid - possibly
by converting parts of it into plasma - to provide propulsive power.

The issue of cost is obviously very important. If the material obtained
from the asteroid is of high value private players will be prepared to
invest in these ventures. If the 500 tons is all gold, the market value
will be more than $ 20 billion.

If we wish to guard against the possibility of a large asteroid hitting
planet earth, we should treat the problem independently from that of
capturing small asteroids. In the case of avoiding a catastrophic impact,
we will mainly be trying to deflect the orbit of the asteroid - however so
slightly.

To avoid a catastrophic asteroid impact:

1. We can keep an eye on the asteroids that have already been detected
(even as we add to this inventory). Is there a one in 20,000 probability
that one of these could suddenly turn rogue?

2. The big question is can we be hit by a large asteroid that we have
failed to detect. What is the probability of this happening; one in a
million?

3. Is it theoretically possible to have a three dimensional radar system
covering the entire solar system which can give advance warning (of say
three years) of a body larger than (say 30 meters), heading towards planet
Earth? What will such a system cost?

4. Evidently we missed the 17 meter asteroid that hit Chelyabinsk. Could it
have been detected?

5. Had we known about this asteroid, could we have predicted that it would
impact over Chelyabinsk?

....

Regards,

Selvaraj

Asteroid capture will not solve the problem of catastrophic loss of life on
the planet in the event of a large asteroid hitting planet earth

On 15 April 2013 23:37, sailor.barsoom wrote: