[meteorite-list] Asteroid Eaters: Robots to Hunt Space Rocks, Protect Earth

[Ron Baalke]

http://space.com/businesstechnology/technology/madmen_techwed_040519.html

Asteroid Eaters: Robots to Hunt Space Rocks, Protect Earth
By Tariq Malik
space.com
May 19, 2004

At the movies, the best way to stop an asteroid from wiping out 
Earth is to lob a few nuclear missiles at the rocky beast or blow 
it apart from the inside with megaton bombs. 

While those methods promise some fantastic explosions
-- and maybe a blockbuster hit -- a team of engineers are
looking at a more patient approach. Their weapon: a swarm of
nuclear-powered robots that could drill into an asteroid and
hurl chunks of it into space with enough force to gradually
push it into a non-Earth impacting course. 

"We're aiming to examine the whole idea of these robots," said
Matthew Graham, design project manager for the study at
SpaceWorks Engineering, Inc. (SEI), an engineering consulting
and concept analysis firm in Atlanta, Georgia. 

SEI researchers have completed a preliminary study into the
robots, called Modular Asteroid Deflection Mission Ejector
Node (MADMEN) spacecraft, under a grant awarded by the
NASA (news - web sites) Institute for Advanced Concepts
(NIAC) to come up with new techniques to defend the planet 
against pesky near-Earth objects (NEOs).

"Previous studies by NASA and NIAC focused on concepts that 
could detect asteroids or bump them using propulsion systems 
of nuclear weapons," NIAC director Robert Cassanova told 
SPACE.com.  "[MADMEN] was rather unique in that it would 
nibble away at the asteroid."

Eating away at a killer asteroid

At the heart of the MADMEN concept is a mass driver, which 
would eject asteroid material as it is drilled out of the rock 
and sling it out into space using electromagnetic acceleration. 
The recoil from that ejection would pushes against the robot, 
and therefore the asteroid, imparting a small amount of force 
for each shot.

"It's like throwing rocks from inside a rowboat," Graham said 
in a telephone interview. "Over time, you end up moving the boat."

A preliminary design for a MADMEN spacecraft outlines a one-ton 
robot that would stand about 36 feet (11 meters) high, just 
slightly taller than NASA's Apollo moon lander, on an asteroids 
surface.

The mass driving ejector, a self-assembling tube, would extend out 
toward space ready to start its slow, steady push against the rock 
at a rate of one shot a minute or so. A liquid-propellant booster
rocket could deliver the lander to its cometary or asteroid target. 

But the push would be small, and more than one MADMEN spacecraft 
would be required to constantly shove a space rock in one, uniform 
direction.

A MADMEN swarm

Since each MADMEN robot could only give a small push to an asteroid 
over time, SEI reseachers envision sending an entire fleet of them 
to a potential Earth impactor. The key, they said, is to have a
lander on each face of an asteroid working together autonomously to 
push the space rock in one direction as it tumbles through space. 

In a presentation to NIAC, MADMEN researchers compared their robotic 
devices to Star Trek's cybernetic juggernaut, the Borg, a species 
that overlooks individual casualties in pursuit of its goals. 

"The benefit of the swarm is redundancy," Graham said. "Some could 
be destroyed, others lost, and the rest can still challenge the 
asteroid."

To build a swarm, MADMEN robots would have to be manufactured well 
before a potentially Earth-threatening asteroid was discovered. A 
stockpile of inert MADMEN spacecraft - each with its own fuel reserve - 
could be gathered into nearby parking orbits where they could be 
called upon if a stray space rock wandered too close.

Deciding how many MADMEN to send, thousands or maybe just four or so, 
would depend on the lead-time before a potential impact, researchers 
said. 

"If you have a good amount of warning, like 10 years, then you don't 
need to send many," Graham added.

More study needed

There are still a number of technological hurdles facing researchers 
before the first MADMEN robot could start its Earth-protecting mission. 
Not the least of which is the mass driver machinery needed to eject 
asteroid chunks into space. 

"People have not made a production versions of this," Graham said, 
adding MADMEN mass drivers would have to continuously fire away 
ejecta on time scales of a year. "So something very reliable and light 
and strong and accurate is needed."

A lightweight space nuclear power plant also requires further study, 
as well as the drilling system that would eventually eat away at 
offending asteroids or comets.

"Drilling systems today mainly use water to move mass up the tube and 
away from the bit," Graham said. "In space, you need to develop a 
closed system to do that."

With the first phase of MADMEN study complete, SEI researchers are 
awaiting a decision from NIAC on whether to fund a second round of 
research that would focus, among other things, on the design of a 
technology-testing precursor mission to be carried out in the next 
decade.

"Phase two means going into more detail, building a roadmap to develop 
the enabling technology for these projects," Casanova said. "We'd like 
to think that NASA would be interested in these projects once a phase 
two study is finished."

Graham said it could be several months before phase two approval for 
the MADMEN project is awarded. He is confident, however, that if the 
need were urgent enough, Earth scientists would be able to step up to 
the task of defending the planet with MADMEN robots or some other 
method.

NASA, Graham explained, has already demonstrated its ability to land 
on as asteroid when the NEAR spacecraft came to a soft landing on the 
asteroid Eros.  Meanwhile, the European Space Agency's Rosetta mission 
is expected to drop its own lander Philae on a comet sometime in 2014.

"If it's a world-killing asteroid, well then it's all about 
motivation," Graham said.