[meteorite-list] SIMONE: Europe's Plan to Explore Near Earth Objects

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:25:45 2004
Message-ID: <200305281538.IAA04704_at_zagami.jpl.nasa.gov>

http://space.com/businesstechnology/technology/simone_esa_030528.html

SIMONE: Europe's Plan to Explore Near Earth Objects
By Tariq Malik
space.com
28 May 2003

A handful of small, asteroid-bound satellites could one day help protect our
planet from space rocks careless enough to cross paths with Earth as they
wander through the Solar System.

At present, researchers with the European Space Agency (ESA) are
evaluating plans to send a five-craft fleet to nearby asteroids and other
objects to learn more about their size, shape and inevitable path through
our planet's neighborhood. The hope is to develop a better understanding of
these rocky neighbors and prepare for the off chance one ends up heading
straight for us.

"Ultimately, this is all driving toward identifying any future physical
impacts," said the project's science leader Simon Green during a telephone
interview. Green is a researcher the Planetary and Space Sciences Research
Institute at Open University in the United Kingdom, which is partnering with
the technology group QinetiQ on SIMONE. "You need to learn as much about
[near-earth objects] as you can in order to identify one that might hit."

SIMONE

The project dubbed the Smallsat Intercept Missions to Objects Near Earth
(SIMONE), is one of six low-cost missions under development by the ESA
earlier this year to study space rocks.

With SIMONE, scientists plan to launch five microsatellites into space, each
headed to a different asteroid. The cube-shaped probes measure about three
feet (one meter) per side and weigh about 264 pounds (120 kilograms).

Once in space, a pair of solar arrays should unfold like wings to generate
the electricity needed to run an ion engine, a propulsion system that uses
electrically charged particles to push a craft through space. NASA used the
propulsion method in its Deep Space 1 mission.

"It's a technology that has been around awhile," said Andrés Gálvez, head of
ESA's Advanced Concepts Team, of the ion drive. "But SIMONE would be the
first time a satellite this small has carried one."

Ion engines are a wonder when it comes to spacecraft fuel efficiently
because they require less fuel than conventional engines, which is exactly
why they are planned for the SIMONE project, Gálvez told SPACE.com.
Electricity from the SIMONE's solar panels is expected to ionize xenon gas
carried in a small donut-shaped tank onboard each of the five probes,
allowing the craft enough power to reach, and stay with, near-earth
asteroids.

"Each [SIMONE probe] is a stand alone craft," Green said. "So for the sort
of budget you'd expect for one large stand alone machine, we get five."

ESA researchers estimate SIMONE to cost around $160 million Euro (about $186
million USD) for all five satellites. That includes each SIMONE payload of a
multispectral camera for imaging, an x-ray spectrometer to determine an
asteroid's composition, a radio science experiment to measure mass, an
infrared spectrometer to seek out any minerals and surface details and a
laser altimeter to take topographical measurements.

"There's quite a lot of clever instruments packed aboard these things,"
Green said.

Crossing paths with asteroids

The Earth is no stranger to impacts by otherworldly objects. Scientists
believe an object the size of a small city slammed into our planet 65
million years ago and led to the extinction of dinosaurs and a crater we now
call Chicxulub in the Yucatan Peninsula.

While that impact was huge, even smaller space rocks can cause devastating
effects. In June of 1908, a 200-foot wide (60-meter) asteroid exploded near
Russia's Tunguska River in Siberia. The explosion released about 10 megatons
of energy, about 500 times that of the atomic bomb dropped on Hiroshima, and
flattened the forest for a diameter of 30 miles (50 kilometers).

"We really don't known much about them," Gálvez said of the smaller
asteroids that swing by Earth. "Not even how many there are."

NASA researchers estimate that there are between 1,000 and 1,500 asteroids
about a half-mile (1 kilometer) in diameter near Earth to worry about. About
640 of them have been found and NASA hopes to have cataloged the bulk of
them by 2008.

But some researchers think that looking for large, kilometer-sized space
rocks, which impact the planet about once every 100,000 years or so, may be
too narrow.

"Statistically, we should be concentrating on rocks down around the
300-to-200 meters (984-to-656 feet)," said Brian Marsden, of the Minor
Planet Center at the Harvard-Smithsonian Center for Astrophysics. "We'd need
to do it, of course, which much more effort than we do today, and with
larger telescopes." Those smaller asteroids hit the Earth every millenium or
so, with even small chunks impacting very century.

Marsden told SPACE.com that while ESA's SIMONE concept is on the right track
in terms of which targets to visit - the five initial asteroids selected
range in diameter from 390 meters to 1,100 meters - he doubts that visiting
individual rocks would lead to better impact estimates.

"You can find Earth-crossing asteroids from the ground, and it takes time,"
he added. "It's more an orbital problem which is not going to be done in a
mission like this."

But where SIMONE can help is in the countermeasure department, Marsden said.
The data from each SIMONE probe should give astronomers a plethora of data
of the composition, mass and characteristics of a spectrum of asteroids.
With enough of that data in hand, astronomers and world leaders could
develop the tools and methods necessary to prevent an impending impact.

""If something is really going to hit us, it isn't going to just go away,"
Marsden said. "So what are you going to do? Do you try to hit it or break it
into pieces? That's where this project becomes useful."

SIMONE rides shotgun

ESA officials said the compact design of each SIMONE probe means more than
just a cheap spacecraft that fits in a box.

"The main point of using a microsatellite is not because we want to so
something small," said Gálvez. "It also makes it much easier to find launch
opportunities."

In theory SIMONE should be small enough to be launched as a secondary
passenger on its Ariane 5 rocket, meaning the ESA wouldn't have to pay top
dollar for using the launch vehicle. That ability increases the flexibility
of the SIMONE concept for use in a variety of other missions as well.

Researchers are already studying the possibility of SIMONE+, a larger
spacecraft similar in design to its smaller precursors that could be used
for missions to Mars and other planets.

Green said the SIMONE project has yet to progress past the development and
study stage, largely due to a lack of funding. With the appropriate funds in
hand, he added, SIMONE probes could be launched by 2008 and make their first
asteroid rendezvous within a four-year period.
Received on Wed 28 May 2003 11:38:26 AM PDT