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SciITech
The Battalion
Page 3 • Wednesday, April 28, 2004
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Nuclear power could help propel spaceships on distant flights into the atmosphere
By Robert S. Boyd
KRT CAMPUS
WASHINGTON — To boost future space-
ps to distant moons and planets, the Bush
inistration is turning to nuclear power, long
a fio-no for a nation nervous about anything to
do with radioactivity.
^■Despite activists’ fears of a nuclear accident,
NlSA has used small atomic generators to power
sck ntific instruments and communications sys
tems on at least 25 space missions over the last 30
years. Unlike batteries, which run down, or solar
^Hiels, which don’t work well far from the sun,
niilear generators give steady, reliable, almost
Junl united power.
E/HEach of the Mars rovers, Spirit and
Opportunity, has eight penny-sized pellets of
■ radioactive plutonium aboard to keep its elec-
Inic instruments warm during the freezing
U^.iMlirtian night. The huge Cassini spaceship,
JSJwlich will reach Saturn in June after a seven-
year voyage, carries 72 pounds of plutonium to
produce electrical energy.
_HTo the dismay of some opponents of nuclear
p a( jprbjects in space or on the ground, NASA has
be; m work on a far more controversial project.
desiMFor the first time, it intends to use a powerful
nia lear-propulsion system to send a large scientif-
lie spaceship, traveling as fast as 50,000 mph, on a
itotu of the ice-covered moons of Jupiter, where
scientists think they might find evidence of life.
^■NASA’s science chief, Ed Weiler, calls the
ship "Battlestar Galactica," after the science-fic
tion TV show.
*"■1116 proposed spaceship will depend on
mjclear fission — splitting uranium atoms — to
.,M>pel it to the neighborhood of Jupiter, starting
""Onetime after 2011.
(When the atoms are split, they will generate
heat that can be converted to electricity. The elec-
trkity, in turn, would accelerate electrically
ncharged hydrogen atoms and speed them out the
rear of the spaceship, thrusting it forward.
jKjjjBThe multibillion-dollar mission is known as
short for Jupiter Icy Moons Orbiter.
e#Vt’s the first phase of a larger NASA program
tli^Bled Prometheus, which is designed to develop
aid Bclear propulsion for a series of space missions,
ftm including the human expedition to Mars that
, bsident Bush proposed in January,
versil)
jil r.-
:mr:
NASA wants to spend $2 billion
developing Prometheus over the next five
years. JIMO’s trip to Mars would cost bil
lions more. "Our nuclear budget is going
up radically," Weiler said
JIMO will be "difficult both techni
cally and politically," Prometheus direc
tor Alan Newhouse acknowledged.
Before the space reactor can get off the
ground, members of Congress will have
turned over several times and one or two
new presidents will have been in the
White House. Support for putting a
nuclear power plant in space may not
last that long.
"It depends on who wins the next
several presidential elections," said John
Pike, an expert on space policy and
director of GlobalSecurity, a nonprofit
organization in Washington. "Another
administration might not want it."
Prometheus officials say a nuclear fis
sion system would give a spaceship up to
100 times more thrust than a non-nuclear
system of similar weight. JIMO could
make the trip to Jupiter in one-third to half
the time of today's vessels, which are
launched by chemical rockets fueled by
hydrogen and oxygen. Using current tech
nology, the trip takes about 38 months.
Furthermore, the current generation
of spaceships, once they've dropped off
their booster rockets, depend on batter
ies or solar power, which have limited
capabilities.
"Solar does not provide enough power at the
outer planets, which are too far from the sun,"
Newhouse said. "Chemical (power) limits maneu
verability and destination. We launch and we
coast. We can't change targets. We can't operate
many instruments. We can't transmit a great deal
of information."
With nuclear propulsion, he said, "we have
power all the way. We can go into orbit, slow down,
stay there, go back, change targets. We have almost
unlimited power for instruments. We can send back
much more data. We have more launch opportuni
ties. We don't have to wait for the planets to line up."
The pro-nuclear enthusiasm of the Bush
administration rankles activists, who oppose put
ting atomic devices in space.
Bruce Gagnon, the coordinator of the Global
Nuclear power for long flight to Jupiter
The Jupiter Icy Moons Orbiter, a crewless space probe planned for some time after 2011, will have
a nuclear engine, which is more powerful than non-nuclear engines but raises safety concerns.
Communication
Radiation
shield
Radar
antenna
Frame
Nuclear
reactor splits
uranium atoms;
reaction creates
Electric
generator uses
heat to generate
electricity
How the thrusters work
Heat radiator
disperses excess.
heat into spac
Electric current
' puts opposite
electric charges
on propellant
and grid
Propellant
Hydrogen, argon
or other gas
Positive
propellant
ions
Negative
grid
p Gas rushes
^ toward grid,
passes
through it*
Backward
force
pushes
spacecraft
forward
* Charge neutralized as gas passes
courtesy of • KRT CAMPUS
Network against Weapons and Nuclear Power in
Brunswick, Maine, is concerned about the envi
ronmental consequences of an accident.
"We're told, 'Don't worry; everything is going
to be safe,"’ he said. "But space technology fails on
occasion. We've seen enough examples, like the
Russian 1996 Mars mission that fell back to Earth
and spread a half-pound of plutonium around.
Imagine if Columbia (the space shuttle that
exploded last year) had a nuclear reactor on it."
NASA officials contend that JIMO will be safe.
They point out that the spaceship will be launched
on a conventional chemical rocket. The nuclear
reactor won't be turned on until it's well out in
space, beyond where it could fall back to Earth.
Even if a spaceship carrying uranium or pluto
nium blew up on the ground — or tumbled to
Earth like Columbia — officials say there's little
risk of harm to people.
Unlike plutonium-239, the stuff of nuclear
bombs, plutonium-238, the material used in on
board power generators, is "quite harmless," said
John Hancher, a geochemist at George Washington
University, in Washington. "It's used in pacemakers
and navigation beacons. Its particles are stopped by
the skin, clothing, even a piece of paper."
Fissionable uranium-235, which would be
used for propulsion, is more toxic. But NASA
says a space reactor isn't like an atom bomb —
it can't explode. The worst effect of an acci
dent on or near Earth would be scattered
radioactive dust, which would be harmful only
if breathed in.
"We will need presidential approval to launch
nuclear material," Newhouse pointed out. "We have
to think of safety up front."
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