Re: Pluto, Plutonium, and the Cold War


Greg D. Moore (Strider) wrote:

>
> Isn't this also Russian Plutonium we bought off of them to reduce the
> proliferation threat?
>
> (and since we shut down I think it was Hanford we haven't made any more?)
>
>

A Space.com article from August 2004 seems to confirm that some Russian
Plutonium
is in the probe RTG's


http://www.space.com/scienceastronomy/pluto_mission_040806.html

Space.Com - August 2004

NASA's Pluto Probe to be Delayed or Make Due With Less Power
By Brian Berger
Space News Staff Writer
posted: 06 August 2004
08:19 pm ET

WASHINGTON - NASA expects to decide by mid-September between postponing
the launch of a nuclear-powered Pluto probe a full year - adding
millions of dollars and three years of travel time to the mission -
and staying on schedule with a less capable spacecraft.

It is not a choice NASA officials relish making. But with all work
halted at the U.S. Department of Energy's Los Alamos National
Laboratory following a security breach, it is almost certain that the
lab will not be able to guarantee all of the nuclear fuel needed to
power the Pluto-bound New Horizons spacecraft by the time NASA needs
it.

The plutonium-238 fuel is used to power a long-lasting spacecraft
battery known as a radioisotope thermal generator, or RTG.

Only about half of NASA's plutonium order was complete when the
Department of Energy halted all work at the nuclear weapons facility in
mid-July after two computer disks containing classified information
were discovered missing. Some administrative work had resumed at the
New Mexico lab by July 29, but Los Alamos Director Pete Nanos told
reporters Aug. 3 that it could be two months before the lab is back to
full operations.

Orlando Figueroa, director of NASA's solar system exploration
division, told Space News Aug. 6 that he no longer expects Los Alamos
to be able to provide all the plutonium-238 that NASA needs in time to
keep the mission on track for a January 2006 launch.

Half on hand

Los Alamos already has about half of the plutonium-238 that NASA needs
for the mission ready to go. This material was left over from a spare
RTG built years ago for NASA's Galileo and Cassini missions.

Prior to the lab shutdown in July, Los Alamos scientists had been
working to fill the rest of NASA's order by turning plutonium bought
from Russia into tiny pellets and then packaging them into modules
roughly the size and shape of hockey pucks.

Los Alamos must deliver the modules to the Argonne National
Laboratory's Idaho Falls facility by February if NASA and the
Department of Energy hope to keep the project on schedule. Argonne's
job is to integrate the modules with the RTG. Three months of rigorous
testing will then follow, including vibration and exposure to intense
cold and vacuum, according to Argonne-West spokeswoman Sara Catherine
Foster.

Figueroa said Los Alamos was already scrambling to make up time lost
during a previous security-related work stoppage and the latest
situation has only made matters more difficult.

"Getting past the first shutdown took a tremendous effort," Figueroa
said. "The latest shutdown took the threat from Code Orange to Code Red
real quick."

The options

Figueroa said NASA could launch the New Horizons probe with a less-than
fully fueled RTG, but that would mean less electrical power for its
seven instruments and other systems. RTGs work by transforming heat
from decaying plutonium into electricity. A fully fueled RTG is
designed to deliver about 200 watts of useable power for the mission.

An RTG running on half the required plutonium would generate only about
half as much power.

Department of Energy officials are expected to tell Figueroa within two
weeks just how much of the requested plutonium can be delivered in time
for a 2006 launch schedule. Meanwhile, Figueroa has directed the New
Horizons team to propose a less power hungry mission that launches on
time.

Figueroa said he would decide by mid-September whether to go ahead with
a scaled-back mission in January 2006 or a fully powered spacecraft one
year later. Waiting a year would actually delay the probe's arrival
at Pluto for four to five years, however.

Getting there

The 35-day launch window that opens in January 2006 is the last
opportunity for nine years to take advantage of a time-saving Jupiter
gravity assist that would enable New Horizons to reach Pluto as early
as late 2014. The next favorable launch window, which opens in February
2007, would add three to four years to the probe's transit time and
between $60 million and $80 million to its $600 million cost.

Given all that can go wrong with a spacecraft in the unforgiving space
environment, adding 1,000 days of cruise time also adds risk.

Alan Stern, the New Horizons principal investigator, said in an
interview that he is evaluating a range of options for making due with
less power and keeping the mission on schedule

"We're looking at where we can save a few watts here and there," said
Stern, of the Southwest Research Institute. "One Christmas tree bulb
worth of power - about 15 watts - could make the difference between
launching on time, or waiting a year."

In their hunt for ways to save power, Stern and his team will consider
everything from keeping certain backup systems inactive during the
cruise phase to turning off some of the probe's excess data storage
capacity.

Getting there quicker

Also under consideration are different trajectories that could get the
spacecraft to its destination months sooner and enable it to complete
its core mission up to a year earlier. Because RTGs weaken over time,
time saved translates into more available power. The tradeoff, Stern
said, is that arriving later could actually be better for one of the
mission's experiments.

Stern said if Los Alamos can only guarantee delivery of the half of
NASA's plutonium order the lab had on hand when it shut down, the
mission would have to wait.

"I cannot run at half power," Stern said. "The answer is probably
somewhere between 170 watts and full power."

In addition to the 36 finished plutonium modules Los Alamos has on hand
from the Cassini and Galileo programs - half of the 72 modules needed
for full power- the lab had another 18 modules in various states of
completion when it stopped work. If a 2006 launch is to remain a
possibility, Stern said, Los Alamos would need to guarantee delivery of
enough plutonium to provide at least 170 watts of power - about 61 or
so modules in all.

NASA is expected to find out from the Department of Energy in the weeks
ahead if Los Alamos can deliver even that many.

Other problems

Figueroa, meanwhile, said the Los Alamos shutdown is not the only thing
putting the January 2006 launch schedule in jeopardy. NASA officials at
Kennedy Space Center in Florida also are facing a very tight schedule
for qualifying the solid-rocket strap-on boosters that will give the
Atlas 5 rocket the added lift it will need to send New Horizons on its
way to Pluto.

Further, the spacecraft is encountering the usual developmental
hiccups, Figueroa said. And because it will use a nuclear power source,
the mission must undergo a rigorous safety and environmental review
before it is cleared to launch.

"From the get-go we knew that making 2006 was going to be very tight,"
he said. "Across the board we knew this was going to be a heck of a
challenge and it has proven to be so every step of the way."

After several abortive attempts during the 1990s to design an
affordable Pluto mission, NASA made a fresh start in 2001 by picking
the Southwest Research Institute from among a number of competing
bidders to design the challenging mission. Its projected $600 million
cost is considered modest by NASA standards.

Any added expense from postponing the mission, Figueroa said, could
probably be accommodated within the budget NASA has set aside for the
broader New Frontiers outer planets program. "Since this mission was so
risk-loaded from the get-go, we have always been playing what-if games
and placed a lien against the New Frontiers program because we thought
that anything at any time could cause a delay."




Rusty

.

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