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

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed May 19 12:56:39 2004
Message-ID: <200405191651.JAA27499_at_zagami.jpl.nasa.gov>


Asteroid Eaters: Robots to Hunt Space Rocks, Protect Earth
By Tariq Malik
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

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

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

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

"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

"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

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.
Received on Wed 19 May 2004 12:50:55 PM PDT

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