[meteorite-list] Stardust to Light Up the Skies on Jan 15 Re-entry

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Dec 27 14:36:56 2005
Message-ID: <200512271920.jBRJKXn03874_at_zagami.jpl.nasa.gov>

http://space.com/missionlaunches/051226_stardust_watch.html

NASA Probe to Light the Skies on Jan. 15 Re-entry
By Leonard David
space.com
26 December 2005

When the Stardust sample return capsule nose dives back to Earth in
January, it will become the fastest human-made object to streak through
the atmosphere. Scientists and engineers are at the ready to observe the
spectacular sky show - and savvy skywatchers can join in on the aerial
action too.

If all goes to plan, Stardust will release its sample return capsule
carrying comet and interstellar dust particles on Jan. 15 at 12:57 a.m.
Eastern Standard Time (EST). Four hours later, the capsule will enter
Earth's atmosphere, zooming toward Utah and a parachute landing at
roughly 5:12 a.m. EST.

During its plummet into Utah the heat-thwarting capsule will skyrocket
across the Western United States [map:
<http://www.space.com/php/multimedia/imagedisplay/img_display.php?pic=051226_stardust_map_02.jpg&cap=Stardust+capsule%27s+entry+track+as+it+heads+toward+Utah.+Credit%3A+NASA/Ames>].

According to Stardust officials, the fireball should be visible from San
Francisco perhaps up to and beyond Portland, shooting over Nevada toward
its Utah landing. The artificial meteor is expected to peak in
brightness as it penetrates deeper in the Earth's atmosphere, lighting
up to roughly the brilliance of Venus for about 90 seconds. That
brightness is expected to peak over Carlin, Nevada.

So if you live in Northern California, Oregon, Washington, Northern
Nevada, Southern Idaho or Western Utah you should be able to see some
part of Stardust sky show. The closer you live to the trajectory, which
runs from Crescent City, California and then through Winnemucca and Elko
Nevada, and finally to Western Utah, the higher the fireworks in the
early morning sky will be.

Speed record

The velocity of Stardust's sample return capsule as it slices through
the Earth's atmosphere is a hasty 28,860 mph (12.9 kilometers per
second). At that speed, the capsule surpasses the record set in May 1969
during the return of the Apollo 10 command module, the highest speed
ever attained by human beings: 24,861 mph (11.11 kilometers per second).

Even at that rate, it still doesn't beat the heat seen by the Galileo
probe as it plunged into Jupiter's atmosphere on Dec. 7, 1995. The small
craft reached a blistering 106,000 mph (47.4 kilometers per second).

But nobody was on the scene to get an eyeful.

Stardust's sample return capsule is a lightweight. It tips the scale at
101-pounds (46 kilograms).

In 2004, Genesis - a sister mission of Stardust - made a similar return,
jettisoning a sample return capsule four-times the mass of Stardust.

Due to improperly placed sensors on the Genesis capsule, however, its
parachute system failed to deploy. That resulted in a precisely placed,
but busted-up capsule when the vessel
hit the desert landscape at high speed. Despite the hard-landing,
researchers remain hopeful they can extract meaningful science from the
returned specimens of solar wind.

Science friction

Four hours after release from the main Stardust spacecraft, the sample
return capsule will enter Earth's atmosphere at 410,000 feet (125
kilometers) over the Pacific Ocean.

At this point, the capsule is about 551 miles (886 kilometers) from its
landing zone in Utah, and on its way to claim the record of the fastest
human-made object ever to enter Earth's atmosphere.

By entry plus 38 seconds, the capsule will have already covered half the
horizontal distance to its landing zone. At this point, friction from
the entry is to raise the capsule's heat shield temperature, making it
observable via infrared tracking equipment.

At entry plus 52 seconds, at an altitude of 200,000 feet (61
kilometers), the capsule will experience peak heating: the heat shield's
exterior will spike at 365 degrees Fahrenheit (185 Celsius). Ten seconds
later, peak deceleration will occur as the rapidly slowing capsule
experiences 38'gs - or 38 times the force of gravity.

Airborne campaign

After nearly seven years of cruising through space, and surviving its
high-speed fall, the Stardust capsule will be on a heading that leads to
the U.S. Air Force Utah Test and Training Range (UTTR), southwest of
Salt Lake City. Spacecraft navigators are looking to plop the capsule
into an ellipse 47 by 27 miles (76 by 44 kilometers) within the UTTR.

Scientists are anxious to scrutinize the fiery fall of the capsule. Data
collected is expected to help understand how natural material incoming
from space is altered as it enters Earth's atmosphere. This information
would be helpful in piecing together a story on chemical changes in
compounds during that process - a puzzle piece for astrobiologists that
study the origin of life.

A crew of researchers flying on a heavily-instrumented NASA DC-8
aircraft will study the small, speeding Stardust capsule returning from
space. They face a daunting task of tracking and observing the capsule
as it hurtles through the atmosphere and slows before parachuting into a
Utah desert landing zone.

Public invite

The airborne campaign is coming together, with the DC-8 arriving on Jan.
3 at NASA's Ames Research Center in Silicon Valley. Once there, it will
be loaded with science gear. A Jan. 11 first test flight is also on the
books.

"We have now turned our attention on setting up ground-based
observations as well, including involving the public in documenting the
reentry," said Peter Jenniskens, principal investigator of the Stardust
Sample Return Capsule Re-entry Observing Campaign. He is a meteor
astronomer at the SETI Institute in Mountain View, California.

"Some observations can only be done from the ground, such as listen for
the sonic boom and observing the hot air trail in the wake of the sample
return capsule drift in front of the Moon," Jenniskens told SPACE.com.

"Also, we'd like to involve the public in taking images and video of the
reentry because the view from each location will be a little different,
depending on how the capsule itself shields the light coming from the
front," Jenniskens said.

Viewing tips

Jenniskens and his research colleagues involved in tracking the Stardust
capsule offer several viewing tips

The capsule will approach the landing zone from a westerly direction.
The best opportunities for viewing the entry will be along Highway 80
between Carlin, Nevada and Elko, Nevada, and further east to the Utah
border, where the capsule's front side can be observed before it passes
over the observer on the ground.

The peak brightness will decrease further from Carlin, lessening to
about the brightness of Venus when seen from Boise, Idaho, and Salt Lake
City. Observers using the naked eye will likely see the capsule as a
very bright pinpoint of pink-white light.

For certain viewing locations just north of the trajectory line, the
capsule will appear to pass by the Moon - above it, or below it, depending
on the viewer's location.

Video, photos welcomed

By choosing their positions carefully, some observers will be able to
see the capsule pass in front of the Moon. As seen by the naked eye, the
capsule will disappear in the glare of moonlight, but by looking through
telescopes, observers may see a tiny dot, perhaps trailed by a dark wake
of dissipating heat shield material and hot air.

Moving at many times the speed of sound, the capsule will take only two
to three video frames to appear to pass by the Moon.

The trail may form a thin line behind the capsule, especially near the
point of peak brightness where atmospheric friction and dissipation of
heat is most intense.

If you would like to become part of the observation campaign, Jenniskens
noted, you can help study the reentry by contributing photos or video to
NASA.

If you'd like to take part in watching the Stardust capsule's
history-making dive into the record books, check out NASA's viewing
forum <http://reentry.arc.nasa.gov/viewingforum.html>.

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http://rockymountainnews.com/drmn/local/article/0,1299,DRMN_15_4343885,00.html

Comet craft nears end of journey
NASA's Denver-built Stardust headed home with samples
By Jim Erickson
Rocky Mountain News
December 27, 2005

NASA's Denver-built Stardust spacecraft has traveled seven years and
nearly 3 billion miles to get from Florida to Utah, passing a comet
along the way.

That's one way to view the $212 million mission, which launched from
Florida's Cape Canaveral in 1999 and will streak to a fiery predawn
finale Jan. 15.

At 2:57 a.m. MST, Stardust's blunt-nosed return capsule will slam into
the Earth's upper atmosphere at more than 28,000 mph, glowing white-hot
and painting the sky with a fireball heralding its return.

Minutes later, if everything goes as planned, the 101-pound capsule will
parachute gently onto the salt flats of the Utah Test & Training range
southwest of Salt Lake City.

Stowed securely inside the capsule are thousands of tiny grains snatched
from Comet Wild 2's dust cloud about a year ago.

If all those specks were compressed into a single pellet, it would be no
bigger than the head of a pin, said Lockheed Martin planetary scientist
Ben Clark, a member of the Stardust science team.

That may seem like a long and costly trip for such a minuscule return,
but Stardust scientists say it's been well worth the effort.

"This is a true treasure," said lead Stardust scientist Don Brownlee of
the University of Washington.

"This is a fantastic opportunity to collect the most primitive materials
in the solar system," he said at a recent news briefing.

"We've collected them, and they're only weeks away from landing on
Earth. It's a thrilling time."

Comets are chunks of ice and dust that orbit the sun. Scientists believe
they hold largely unaltered remnants of the spinning disk of gas and
dust that formed the solar system 4.6 billion years ago.

The comet grains returned by Stardust should help scientists refine
theories about the birth of our planetary system. And they may shed
light on the role comets played in delivering water and organic
molecules to the newborn Earth.

Flawless mission so far

But there's more than science riding on the capsule's return. Pride and
possibly lucrative NASA contracts are also at stake.

The Stardust capsule is similar to, though smaller than, NASA's Genesis
capsule, which crashed into the Utah salt flats at 193 mph on Sept. 8,
2004, after its parachutes failed to open.

The capsule was designed to be plucked in mid-air by hovering
helicopters before it touched the ground.

Instead, it slammed edge-on into mud and shattered fragile silicon
wafers etched with billions of bits of the sun's outer atmosphere. Even
so, Genesis scientists said they expect to achieve most of their science
objectives.

Both Genesis and Stardust were built by Lockheed Martin Space Systems in
Jefferson County.

The Genesis parachute failure was quickly traced to four small
cylindrical switches that were installed backward at the company's
Waterton Canyon facility. The so-called gravity switches were supposed
to detect the craft's deceleration and trigger the sequential release of
two parachutes, a funnel- shaped drogue and a main parafoil.

Since the Genesis crash, NASA and Lockheed Martin have spent about $10
million to verify that Stardust won't suffer the same fate - and guard
against other potential pitfalls - said Joe Vellinga, the company's
program manager for both Stardust and Genesis.

Blueprints, photographs of Stardust circuit boards and records from
prelaunch tests have convinced NASA and Lockheed Martin officials that
the Stardust gravity switches were installed correctly and will perform
properly.

So far, the spacecraft has performed flawlessly throughout its 2.88
billion-mile journey, so there's little reason to think it will fail
during re-entry and landing, said Allan Cheuvront, Lockheed's deputy
program manager for the Stardust mission.

But who knows what can happen when you fling a 7-year-old capsule at
Earth faster than any previous man-made object? At 28,860 mph, Stardust
will break the speed record set in 1969 by the returning Apollo 10
command module.

"Bringing it home for the first time is the only way to test a system
like this," said Ed Hirst, Stardust mission system manager at NASA's Jet
Propulsion Laboratory in Pasadena, Calif. "So there is some residual
risk that something could happen on return. We think the probability of
that is very low at this point."

About 1,000 of Lockheed Martin's Waterton Canyon employees worked on
Stardust, which launched Feb. 7, 1999.

"We know we have a good spacecraft, and my gut tells me everything's
going to work just the way we planned it," Cheuvront said.

A successful Stardust landing could help heal wounds still fresh from
the Genesis incident. At the same time, it might boost the company's
chances of landing a multibillion-dollar NASA contract to build a
replacement for the space shuttle.

Lockheed Martin Space Systems is competing against a Northrop
Grumman-Boeing team for the Crew Exploration Vehicle contract.

In September, NASA announced the next-generation spacecraft will
resemble an oversized Apollo space capsule. At the time, a Lockheed
Martin executive said the company's recent experience with state-
of-the-art capsules - including Genesis and Stardust - gave it an edge
in the competition.

But a second Utah failure might hurt the company's prospects, Vellinga
said. The space agency also is planning unmanned sample-return voyages
to the moon and Mars and the return phase of those missions could borrow
elements of the Genesis and Stardust missions.

"I don't know that I'd call it critical, but it will certainly be a good
data point that we've successfully entered," Vellinga said of a safe
Stardust landing.

Team plans for all scenarios

Stardust is the first journey to a comet and back. It is scheduled to
land at around 3:12 a.m. MST on Jan. 15. Live coverage and commentary
will be provided by NASA-TV, which is available at www.nasa.gov .

On the night of Jan. 14, JPL navigators and Lockheed Martin flight
engineers at Waterton Canyon will guide Stardust to the Utah range.

Four hours before atmospheric reentry, the 32-inch-diameter return
capsule will separate from the Stardust mother ship and begin its final
descent. Two cable cutters will sever umbilicals linking the craft and
small explosive charges will release three retention bolts securing the
capsule to the ship's belly.

At 2:57 a.m., the capsule will enter the atmosphere at an altitude of
406,000 feet. Radar and infrared cameras at Utah's Hill Air Force Base
will be trained on the projected re-entry point.

Atmospheric friction will slow the Stardust capsule and broil its
plastic-impregnated carbon-fiber heat shield to 4,900 degrees
Fahrenheit, Vellinga said.

A streaking fireball should be visible from northern California to
Oregon and throughout Nevada, said Tom Duxbury, Stardust project manager
at the Jet Propulsion Laboratory. It won't be visible in Colorado.

Sensing the deceleration, the gravity switches will activate a timer
that orchestrates the deployment of the stabilizing drogue parachute
about 100,000 feet above the desert.

At about 6,000 feet, the 27-foot-diameter main parachute will unfurl. A
UHF radio beacon fixed to the main parachute's bridle will broadcast a
locator signal for up to 20 hours.

If everything goes as planned, the capsule should settle gently on the
flats at about 10 mph.

If the weather is clear and calm, helicopters will retrieve the capsule
and take it to a nearby clean room before shipping it to NASA's Johnson
Space Center in Houston.

If it is stormy, two all-terrain, rubber-tracked vehicles will converge
on the landing site.

If Stardust's parachutes fail, the capsule will slam into the ground at
150 to 200 mph, Vellinga said. Whether it remains intact will depend on
the impact angle: nose-down or edge-on.

"If it lands edge-on, it will probably be breached, very much like
Genesis was," he said.

The precious comet samples are stored in 130 ice cube-size blocks of a
spongy glass foam called aerogel. Sometimes called blue smoke, aerogel
is 99.9 percent air and is the lowest-density solid known.

When Stardust traversed Comet Wild 2's dust cloud last January, the
spacecraft extended a tennis racket-shaped particle catcher bearing the
aerogel blocks.

Thousands of comet-dust specks - each smaller than a grain of sand - hit
the aerogel cubes at speeds six times faster than a bullet from a
high-powered rifle. The gel gently slowed and stopped the grains, which
excavated conical tracks up to 200 times their own length.

Then the particle catcher was retracted and sealed inside an aluminum
canister for the ride home.

Scientists said they are hoping to recover about 1,000 particles 15
microns in diameter, or about one-third the thickness of a human hair,
Clark said.

Those grains will be sliced into even smaller samples for lab tests to
determine their exact composition.

"Since the dawn of the Space Age, people have been wanting to go to
comets and get some of that material and bring it back to Earth," Clark
said. "So there's now a whole bevy of scientists that are just licking
their lips, waiting to get their hands on this material."

If the Stardust return capsule crashes and breaks open Jan. 15, the
recovery team will try to find individual blocks of aerogel that may be
strewn across the ground.

The team trained for that possibility at night, using flashlights and
high-powered, helicopter-mounted searchlights, Vellinga said.

"We have planned for and tested for all the contingencies that you can
imagine," he said. "So if it is a hard landing, we're trained and
prepared for picking up the capsule - even including loose aerogel - if
it were to be breached."
Received on Tue 27 Dec 2005 02:20:33 PM PST