Prometheus -NASA nuclear reactor project to jupiter

[M, Nivas]

NASA (news - web sites) has embarked on a challenging

quest to build a powerful nuclear reactor for

long-duration deep space excursions. 



As part of the multi-pronged Prometheus Project,

engineers and scientists are now tackling plans for

the nuclear-powered Jupiter Icy Moons Orbiter (JIMO).

This flagship mission using electric propulsion

powered by a nuclear fission reactor would showcase a

slate of key technologies. It also promises to usher

in a new era of solar system exploration. 



The amount of power available to JIMO from a nuclear

reactor would be hundreds of times greater than on

current interplanetary spacecraft.



JIMO's ambitious interplanetary passport -- departing

Earth no earlier than 2011 -- calls for orbiting three

planet-sized moons of Jupiter: Europa, Ganymede, and

Callisto. Each moon may harbor vast oceans beneath

their icy surfaces. Loaded down with science

instruments, JIMO's tour allows for inspecting the

makeup of these moons, their history, and their

ability to support life.



But building JIMO is no cakewalk. 



The technical hurdles ahead are daunting. So much so,

there is a cynical running joke within some corners of

the space science community that the icy moons of

Jupiter may thaw before JIMO ever shows up.



Paradigm buster



A JIMO milestone was met this past April with NASA

awarding study contracts to Boeing, Lockheed Martin,

and Northrop Grumman Space Technologies. Those mission

studies are to be completed by year's end.



Early feedback from the trio of contractors is

heartening, said Alan Newhouse, Director Project

Prometheus, the Nuclear Systems Program at NASA

Headquarters. 



"I was very encouraged by the breadth of thinking that

they are promising us. Whether they deliver of course,

we'll know when they do it," Newhouse told SPACE.com .



JIMO does not signal incremental change. It's a

"paradigm buster," explains Colleen Hartman, Director

of the Solar System Exploration Division within NASA's

Office of Space Science. 



"This is a huge leap for mankind…not a tiny step,"

Hartman noted at a Women in Aerospace (WIA) forum on

new initiatives in space science held last month in

Washington, D.C.



Why the icy moons of Jupiter as JIMO's destination?



"We're following the water. That's one of the main

tenants of NASA…because we know that where there is

water there is life on Earth," Hartman said. "Is that

going to be true throughout the solar system? Frankly,

I certainly don’t know. There is energy. There is

water. There are organics. There is a possibility of

life. So that's why we are endeavoring this icy moons

tour," she explained.



Issues ahead



Whether or not JIMO winds up slipping year after year

due to problems in fabricating a space-rated nuclear

reactor is an issue still to be dealt with. 



That's the view of Jerry Grey, Director, Science and

Technology Policy for the American Institute of

Aeronautics and Astronautics (AIAA). "It's not going

to be easy. But it's certainly worth doing," he told

SPACE.com .



Grey underscores the challenging, long road ahead. 



Among issues are special orbit precautions -- putting

JIMO into a nuclear safe orbit, to checkout hardware

and activate the space reactor high above Earth. Then

there's the shielding problem, making sure JIMO's

delicate science instruments aren't toasted by the

reactor's radiation. Yet another matter is radiating

waste heat from the reactor into space.



"One of the biggest concerns in nuclear systems is

development and testing," Grey said. Ground facilities

for building and checking out new nuclear systems will

be costly, take a long time, and involve a high-level

of safety precautions, he said.



"And until we do proper testing, we're not going to

fly any Prometheus systems," Grey said.



Add to this mix public perception. 



"Most of what the public perceives about nuclear

systems is wrong…but they perceive it that way.

Therefore, you had to deal with it," Grey said. 



Time to Investigate



Handling public perception about danger from nuclear

systems is part of NASA's overall strategy in moving

forward on Project Prometheus and JIMO.



"I appreciate the fact that NASA's papers that have

been put out on Prometheus have said it will be a very

open, transparent process for the public to see into,"

said Kristine Svinicki, Senior Policy Advisor for

Republican Senator Larry Craig of Idaho. That state is

home for the U.S. Department of Energy (news - web

sites)'s Idaho National Engineering and Environmental

Laboratory, and the future site of advanced nuclear

reactor work.



Svinicki said that much of the solar system remains

impossible to adequately explore without new nuclear

propulsion systems. That is a significant limitation,

she said, and the public needs to make a candid

assessment of that constraint.



"It's a question for the American people," said NASA's

Hartman. "The laws of physics can't be broken. If you

want to go to the outer planets, to be an explorer of

this solar system, to understand comparative planetary

biology…the American public pays for it. So I believe

it is their choice," she said.



Hartman said that power is essential for JIMO to

obtain the kind of science observations hoped for. 



"You want to have time on target. If you are whizzing

by Las Vegas, you're not going to gamble very much. If

you sit and stay…that's basically the idea here. You

can investigate what's there. You can have serendipity

take place," Hartman said.



Ground shakeouts



Putting the pieces together to make JIMO real is a

massive tradeoff between many knotty technical issues.

And there is also need to keep an eye on the nuclear

engineering workforce.



"We are very short of graduate nuclear engineers that

know anything about aerospace and vice versa," said

NASA's Newhouse. The space agency has begun to come to

grips with this situation, he said.



Newhouse said that ground checkouts of JIMO hardware

means use of large chambers that mimic the thermal and

vacuum environment of space. "You have to be very

careful in making a decision to do a ground test or

not do a ground test," he said.



Also there's need for ground shakeouts of JIMO's ion

engines -- or Hall thrusters now used extensively in

commercial applications for satellite station-keeping

-- essential hardware that must be long-lived to push

the spacecraft to Jupiter over years of thrusting.

Departing no earlier than 2011, JIMO's

Earth-to-Jupiter transit time might be as long as

seven years.



Magic mantra



Reducing the overall mass of the spacecraft is what

Newhouse labels as the "magic mantra" for the JIMO

effort.



In the nuclear design process, Newhouse added, certain

testing called "criticals" will be necessary, making

use of nuclear fuels to assure reactor performance is

up to snuff. Any nuclear testing is to be done under

the auspices of the Department of Energy. 



"I certainly don't want to have a reactor that's never

been run before…never been tested…then turned on en

route to Jupiter. That's not a good idea," Newhouse

said. "We will probably want to do a full-up test of

something that looks like the reactor we want to fly

in space," he said.



Newhouse said that one of the most difficult issues is

ground testing. On the nuclear side of the business,

facilities have aged and, in some cases, are no longer

operable. Industry contractors, as part of their JIMO

plans, are outlining ground testing plans and facility

requirements.



Despite being faced with years of hard-nosed

engineering, Newhouse points to one maxim he embraces.

"It is easy to go nowhere. It requires no energy and

has no risk except that of being left behind. To go

forward and run ahead is a supreme test."





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