Date: Fri, 29 Jun 2007 09:39:54 -0400
From: "Michael Walsh" <MJW at press.jhu.edu>
To: <wsfalist at keithlynch.net>,<wsfa-forum at yahoogroups.com>
Subject: [WSFA] Whoops ....Re: Jetpacks ...
Reply-To: WSFA members <WSFAlist at KeithLynch.net>

> ekovar at panix.com 06/28/07 9:32 PM >>>
>Michael Walsh wrote:
>> http://sciencenow.sciencemag.org/cgi/content/full/2002/826/2
>
>"Subscribe/Join AAAS or Buy a Site Pass to View Full Text. The
>content you
>requested requires a AAAS member subscription to this site or
>ScienceNOW
>Site Pass purchase. If you already have a user name and password,
>please
>sign in below."

Well, ain't that interesting.  I guess my .edu address gets me the
access.

Anyway, here's the text:

It's Not Easy to Derail a Roach

By sticking tiny cannons on the backs of cockroaches to see how their
recoil jars the insects' balance, researchers have added firepower to a
new mathematical model that explains how roaches move so nimbly. The
model has already helped them design a better robot bug.

Cockroaches such as the 44-millimeter-long Blaberus discoidalis from
South and Central America can scamper over rugged terrain with
remarkable agility and speed. How do they keep their balance?
Integrative biologist Robert Full of the University of California,
Berkeley, suspected that some of the insect's balance-preserving
reflexes may be too fast to be controlled by its nervous system alone
and are also built into its mechanical structure. Full calls these
responses "preflexes." Working with a team of Princeton University
mathematicians, Full developed a mechanical model of the roach with its
legs acting like springs. Just the mechanical properties of muscles and
exoskeleton, they found, could account for the insect's stability.

The obvious way to check the model--by throwing real roaches off
balance and observing how they regained their footing--wasn't so simple.
After trying everything from magnets to spring-loaded projectiles,
integrative biologist Devin Jindrich, now at the Harvard School of
Public Health in Boston, decided on jetpacks of sorts. These
2-centimeter-long plastic tubes filled with explosives, triggered by
electrical wires, delivered 10-millisecond bursts. Gluing these to
roaches' backs, they observed how running bugs reacted when a quick
blast knocked a leg off balance. The performance was astonishing. "They
didn't even break their stride," Jindrich says.

This rapid recovery rivals the fastest nervous reflexes and thus
bolsters their model, the scientists report in the 15 September Journal
of Experimental Biology. Comparative biomechanist Andrew Biewener of
Harvard University's Concord Field Station in Bedford, Massachusetts,
agrees. Furthermore, he suggests that "a lot of the principles of
movement that apply to invertebrates here are going to apply to
vertebrates as well," meaning that intrinsic properties of muscles and
skeleton may be more important to animal movement than thought.

Full and engineer Daniel Koditschek at the University of Michigan, Ann
Arbor, have designed a breadbox-sized robot with springy limbs like a
cockroach. It scrambles at 3 meters per second over rough terrain. Full
says this simple model for stability has helped liberate computing power
that can now be used for navigation and path-planning.

--CHARLES CHOI

It comes with a photo of the cockroach with a jetpack ... which you
should be able to see here:
http://amos.indiana.edu/library/scripts/rocketroach.html