In article ,
ess says...

On 4/09/2018 9:29 AM, wrote:
"The notion of an asteroid headed for Earth is typically seen as a bad omen. On
the flip side, some scientists and entrepreneurs increasingly see this scenario
as a potential opportunity. Deliberately redirecting asteroids to our planet?s
vicinity could enable us to study them up close, or even mine them.

Given that these objects are packed with valuable resources, building a
collection of them nearby could spark major advances in spaceflight, to say
nothing of the scientific research that might result from easy access to these
extraterrestrial bodies.

A recent paper published in Acta Astronautica suggests that asteroids could be
captured in Earth?s orbit with aerobraking, a maneuver that uses atmospheric
drag to decelerate and position objects in stable trajectories around a planet.
Aerobraking has helped place interplanetary spacecraft in orbit around Mars and
Venus, and to slow down spacecraft returning to Earth.

Led by Minghu Tan, a PhD student at the University of Glasgow, the paper
immediately addresses the most obvious concern with this scenario: What if
there?s some mistake in the redirect process and an asteroid accidentally
impacts Earth? It?s bad enough that the dinosaurs were oblivious to their
doomsday space rock, but it would be especially embarrassing if we humans smack
ourselves in the face with one."

See:

https://motherboard.vice.com/en_us/a...o-earths-orbit


After the aerobraking pass, you need to raise its perigee quite a lot,
or it's just going to come back and burn up, either on the next pass, or
some subsequent pass.

The article doesn't say how the perigee would be raised. Unless they're
planning on using a lunar flyby, I don't see how you can do this without
a sufficiently large rocket engine.

I'm not an expert in orbital mechanics but I do agree you have to
somehow raise the perigee after the aerobraking pass(es) is(are) done.

Giving that we're talking about a hugely massive object, this seems a
big ask.

Yep. I'd rather drop Kuiper belt objects on Mars myself. No danger to
humans on earth. :-)

Jeff
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