UFO UpDates Mailing List
From: XianneKei@aol.com
Date: Sun, 16 Mar 1997 12:52:06 -0500 (EST)
Fwd Date: Sun, 16 Mar 1997 22:31:27 -0500
Subject: It's Just 2.5 Miles of Yarn
c The Associated Press
By MARCIA DUNN
CAPE CANAVERAL, Fla. (AP) - For nearly a year, America's ``other
space agency'' - the super-secretive National Reconnaissance Office
- has been monitoring a bright, white object streaking through the
night sky.
Don't fret: It's not a UFO. It's 2 1/2 miles of knitting yarn.
The single strand of reinforced acrylic yarn has been orbiting
Earth, unwound, since last June.
The National Reconnaissance Office is intrigued by the
possibility of using tethers to connect clusters of small
satellites so they can communicate, much like a computer network.
Other tantalizing applications: using tethers to power
spacecraft by generating electricity as the conductive cords sweep
through Earth's magnetic field, to propel spacecraft into different
orbits and to drop experiments from a space station.
This is the longest-lasting space tether yet, a $4 million
experiment to demonstrate the motion and survivability of tethers
in low Earth orbit, littered with micrometeoroids as well as space
junk.
It's also the first unclassified, ongoing space project in the
36-year history of the National Reconnaissance Office.
The NRO typically flies spy satellites.
``It's really fantastic to call people up on the phone and say,
`Hi, I'm Scott Larrimore and I'm with the NRO and I'd like you to
track my spacecraft. It catches a lot of open mouths,'' said
Larrimore, an Air Force captain who is program manager for the
tether experiment.
Still, the NRO has some things to be closemouthed about.
The NRO refuses to say how or when the shoestring-like tether
was rocketed into orbit or how or when its next tether experiment
will fly. Until December, all NRO launches were classified for
so-called national security reasons.
What it will say, on the record, is this:
The Tether Physics and Survivability experiment, called Tips,
was ejected from a classified military satellite on June 20, 1996,
into a 635-mile-high orbit that swings as far north as Alaska and
as far south as Chile's Cape Horn. A few hours later, the yarn -
all 2 1/2 miles - was unreeled from a spool. The tether, which weighs
12 pounds, was bowed and swung like a jump rope, but eventually
straightened and became more perpendicular to Earth.
Nine months later, the yarn still is orbiting Earth, intact. The
NRO knows so because of ground-based laser, radar and telescope
observations. Amateur astronomers also keep unofficial tabs on the
tether. (It's visible with binoculars on a clear night, although
you need to know exactly where and when to look.)
Tips has outlived its predecessors by months. NRO officials say
if the tether isn't broken by a micrometeoroid or other debris, it
could orbit for as long as 27 years before plunging through the
atmosphere and burning up.
The last time a tether flew, aboard space shuttle Columbia in
February 1996, the 12-mile conductive cord snapped within five
hours because of an electric discharge. The satellite-on-a-string
drifted away like a lost balloon. On the first flight of the $400
million NASA-Italian Space Agency system, aboard Atlantis in 1992,
a protruding bolt caused the tether to jam a mere 840 feet out.
Despite all the trouble, the two missions proved electricity
could be generated by a tether system - easy power for spacecraft.
And the unintended severing of the tether demonstrated that the
higher of two objects goes up when a tether is cut and the lower
one goes down slightly - a fuel-free way to boost spacecraft into
longer-lasting orbits.
A shuttle, for example, could depart from the future
international space station via a tether. Once that tether is cut,
the shuttle would drop and the station would rise - a win-win
situation.
NASA successfully flew three simpler and cheaper tethers on
unmanned Delta rockets in the early 1990s. The third test ended
abruptly, however, when the 12-mile line was severed, most likely
by a micrometeoroid, just three days and 17 hours after it was
unreeled.
The only other orbiting tethers to date: 100-foot cords linking
manned capsules and Agena boosters during Gemini 11 and 12 in 1966.
NASA's next shot at a tether? Not until 1999 and most definitely
not on a space shuttle, where astronaut safety is paramount. The
space agency dumped a tether experiment that was to have flown on
Discovery this July.
``Things have really been ramped back because of the squeeze on
the budget and the bad experience we've had with tethers,'' said
NASA project manager Jim Harrison.
Added astronaut Jeffrey Hoffman, who flew on both
tethered-satellite missions: ``It's an emotional impact. What can
you say? It would have been better if it hadn't broken.''
Unlike NASA, the NRO wanted as plain a tether system as
possible.
The 2 1/2 miles of white yarn is wrapped in braided Spectra 1000, a
tough, white fiber used in bulletproof vests and fish lines. The
resulting nonconductive cord is about one-tenth of an inch thick.
On either end of the Tips tether is an aluminum, hexagonal box
covered with 18 laser reflectors. The box containing the
NASA-donated unreeling device and long-dead electronics has a mass
of 83 pounds. The other box is 23 pounds.
The names of the boxes: Ralph and Norton, respectively.
Remember Ralph Kramden and Ed Norton of ``The Honeymooners?''
``It tickled my funny bone and I got away with it,'' said Bill
Purdy, program manager for the Naval Research Laboratory, which
designed and managed the Tips experiment for the NRO.
The NRO and NRL aren't the only ones picking up where NASA left
off.
The engineer who developed the Tips tether, Joe Carroll of
Tether Applications in Chula Vista, Calif., has a 22-mile cord
that's supposed to ride on a European Ariane 5 rocket later this
year. He's also working on a tethered capsule that might be used to
return experiments from the future international space station.
And Rob Hoyt of Tethers Unlimited in Seattle is working on a
fishnet stocking-type tether. Why fishnet? If one string breaks,
the tether still holds.
Hoyt's most far-flung project: rotating tethers that work like a
bola to hurl payloads from Earth orbit to the moon.
As for the space elevator envisioned by science fiction writer
Arthur C. Clarke, lifting people and cargo to geosynchronous orbit
22,300 miles up, that's farfetched - for now.
No material currently exists that's strong enough, yet
affordable, for such a long, long tether.
``You get on an elevator and you push a button to go to geo,''
Carroll said. ``That's the 10-millionth floor. That's going to take
a while.''
A brief look at the eight orbiting tethers to date:
September 1966: 100-foot Dacron cord links manned Gemini 11
capsule and Agena booster.
November 1966: 100-foot Dacron cord links manned Gemini 12
capsule and Agena booster.
August 1992: 12-mile conductive tether with satellite on end
jams 840 feet out while being unreeled from space shuttle Atlantis.
March 1993: 12 1/2-mile tether launched on Delta rocket,
intentionally cut two hours after being unreeled and re-enters
atmosphere and burns up.
June 1993: One-third-mile conductive tether launched on Delta
rocket, orbits for 1 1/2 months to two months before re-entering
atmosphere and burning up.
March 1994: 12 1/2-mile tether launched on Delta rocket, severed
three days and 17 hours after being unreeled, most likely by
micrometeoroid. Remaining tether and booster segment orbit for 59
days before re-entering atmosphere and burning up.
February 1996: 12-mile conductive tether with satellite on end
breaks while being unreeled from space shuttle Columbia. Tethered
satellite orbits for 23 days before re-entering atmosphere and
burning up.
June 1996: 2 1/2-mile tether ejected into orbit from classified
military satellite, still intact and flying.
AP-NY-03-16-97 1202EST
Copyright 1997 The Associated Press. The information
contained in the AP news report may not be published,
broadcast, rewritten or otherwise distributed without
prior written authority of The Associated Press.
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