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Location: UFOUpDatesList.Com > 2004 > Mar > Mar 30

Havoc In The Heavens

From: Frank Warren <frank-warren.nul>
Date: Tue, 30 Mar 2004 06:33:21 -0800
Fwd Date: Tue, 30 Mar 2004 21:10:39 -0500
Subject: Havoc In The Heavens



Source: Space.com

http://www.space.com/news/mystery_monday_040329.html

29 March 2004

Havoc in the Heavens: Soviet-Era Satellite's Leaky Reactor's
Lethal Legacy
By Leonard David
Senior Space Writer

Old Soviet nuclear powered satellites leaked a trail of menacing
radioactive droplets that have become a debris threat to other
spacecraft.

Tiny spheres of liquid sodium-potassium (NaK) reactor coolant
dripped from the former Soviet Union’s radar ocean
reconnaissance satellites, known as RORSATs. This class of
satellite -- no longer launched -- carried a nuclear reactor to
power a large radar dish that enabled day/night snooping of
Earth’s oceans.

After a RORSATs tour-of-duty was over, the reactor’s fuel core
was shot high above Earth into a "disposal orbit". Once at that
altitude the power supply unit would take several hundred years
before it reentered the Earth’s atmosphere.

However, in ejecting the core from the main body of a RORSAT, a
plumbing problem plagued the satellite design. Faulty seals
permitted the NaK coolant to leak, leaving thouands upon
thousands of droplets to spill freely in to space.

Hazard to spacecraft

RORSATs were orbited by the Soviets starting in 1967 and stopped
in 1988.

There is evidence from ground-based radar measurements that 16
of a total of 31 RORSAT nuclear reactors orbited lost coolant
following core ejection into disposal orbits.

Paula Krisko, a space debris specialist working for Lockheed
Martin at NASA’s Johnson Space Center (JSC) in Houston, Texas,
noted in a recent newsletter dedicated to orbital debris
research that the NaK droplets have been observed over the last
decade.

Not only have the spheres come under scrutiny by several NASA
radars, Krisko explained, they were also found to have dinged
the Long Duration Exposure Facility, better known in NASA lingo
as LDEF. This school bus-sized spacecraft floated through space
for well over 5 years before being plucked from orbit and
returned to Earth by shuttle Columbia in 1990.

Krisko explained that a study of the NaK coolant droplets
circling Earth, floating about in varying sizes, is estimated to
be 110,000 to over 115,000 in number.

"This population represents an orbital debris hazard to
spacecraft in low Earth orbit," she stated.

Radar studies

Credited with first flagging the Soviet leaking reactor problem
was Don Kessler. He has over 40 years of experience in the
scientific study of human-made space trash, a large chunk of
that time spent at the NASA JSC delving into the problem of
space debris.

Kessler is now an orbital debris and meteoroid consultant in
Asheville, North Carolina.

There has been a significant change in the RORSAT story since
Kessler and his colleagues first reported the problem in 1995.
"It is now accepted by all, even by the Russians, as being
correct and is now part of all orbital debris models," he said.

NASA's main source in spotting the drifting droplets was the
Haystack radar. That facility is operated by Massachusetts
Institute of Technology’s (MIT) Lincoln Laboratory and has been
collecting orbital-debris data for NASA since 1990 under an
agreement with the U.S. Air Force.

Kessler led the effort to discover the cause of an abnormally
high concentration of objects that was detected by the Haystack
radar.  These small objects were zipping about the Earth between
roughly 530 miles (850 kilometer) and 620 miles (1,000
kilometer) altitude.

Something strange going on

"Our first clue that something strange was going on," Kessler
said, was the high concentration of objects near 600 miles (900
kilometers) above Earth. That intensity of objects could not be
explained by an explosion, which would have dispersed the debris
over a larger altitude range, he added.

"The concentration was so high that, whatever the source, it
represented the most significant impact hazard for spacecraft
operating at those altitudes... and still does today," Kessler
said.

Early work involved techniques using the Haystack radar to
sample the environment by simply counting objects as they passed
through the radar beam. The advantage of this was that
researchers were able to statistically sample the environment of
much smaller objects, Kessler explained. Altitude and radial
velocity of the droplets could be accurately measured. But only
rough measurements of motion direction and size of the objects
could be ascertained, he said.

Stare and chase

The final proof came when NASA asked MIT to develop a "stare-
and-chase" procedure where they could track some of the larger
objects long enough to develop orbits.

"We used all this information, plus other sources of
information, to determine the source," Kessler said. That source
of spheres made of NaK coolant was found to come from the
seeping RORSATs, he said.

Kessler told SPACE.com that follow-on NASA work has pegged the
total mass of leaked NaK as over 360 pounds (165 kilograms) --
 greater than he had orginally estimated.

A report on the RORSAT leakage in 1997, led by Alessandro Rossi,
a researcher at the Centro Nazionale Universitario di Calcolo
Elettronico (Electronic National University Center for
Calculation) in Pisa, Italy, pointed out another issue.

Rossi stated that, although the NaK coolant leakage may have
been confined to a specific class of satellite no longer
launched, "the probability that a debris impact might puncture
the radiator of one of the RORSATs still in graveyard orbit,
inducing a new leak from the secondary cooling circuit, is far
from negligible."

Well-defined and publicized

"The issue has been well-defined and publicized," said Nicholas
Johnson, Program Manager and Chief Scientist at the NASA JSC’s
Orbital Debris Program Office.

There is a large population of NaK droplets primarily around 560
miles (900 kilometers) altitude above Earth, Johnson explained.
Some of the largest of these are in the roughly 2 inches to 3
inches (5 to 7 centimeters) diameter category. They have been
cataloged by the U.S. Space Surveillance Network and are
routinely tracked, he said.

The vast majority of the droplets are smaller, down to less than
an inch in diameter, Johnson said. "They are not decaying
rapidly, although some very small particles have reached lower
Earth orbits."

Johnson told SPACE.com that "they pose potential mechanical
damage to other spacecraft, just as more conventional debris of
the same size."

Radioactive droplets?

There is one added element to the RORSAT reactor coolant saga.
Are those droplets radioactive?

Any object, large or small -- a paint fleck or a tiny
radioactive sphere -- whizzing about Earth at high speed is
troublesome to both piloted and automated spacecraft.
Furthermore, eventually those NaK spheres will nose-dive into
the upper atmosphere.

There is no doubt that the NaK coolant was radioactive when a
RORSAT was running, said Gerald Kulcinski, associate dean for
research in the College of Engineering and a professor of
nuclear engineering at the University of Wisconsin at Madison.
In the process, both Sodium-24 and another isotope, Argon-39
would have been created, he said.

While the radioactive Sodium-24 is short-lived, any Argon-39
released would have a half-life of 270 years, Kulcinski noted.

That being said, however, just how much of that Argon-39
radioactive isotope is encapsulated within a space-frozen NaK
coolant droplet is not immediately clear, Kulcinski added.
Specific engineering details of how the RORSAT reactor was
designed and functioned would be required. Yet another unknown
factor is what impurities could have been resident within the
NaK coolant, he said.

Runaway threshold

The NaK droplets represent only the "short-term" issue, Kessler
said. He underscored another concern -- terming it a "runaway
threshold". That is, collisions in space would increasingly
produce large quantities of smaller debris over the next 50
years or so.

"Since we began looking, we have measured debris not only from
sources like the NaK, but from solid rocket motors that eject
large amounts of centimeter-to-micron-size objects, paint flecks
from painted spacecraft surfaces, copper needles from U.S. Air
Force communication tests, and more fragments than expected from
explosions in space," Kessler said.

"In the long-term, debris resulting from collisions is still the
major problem, and will be the most expensive to control,"
Kessler said. "We are on the threshold, if we have not already
exceeded it, of reaching a ‘critical density’ of objects in low
Earth orbit, where collisional fragmentation will cause the
debris environment to slowly grow even if all other sources are
eliminated."






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