[meteorite-list] Ball Aerospace Set To Ship Deep Impact This Month

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Sun Oct 3 16:54:23 2004
Message-ID: <200410032054.NAA27934_at_zagami.jpl.nasa.gov>

http://www.bouldernews.com/bdc/science/article/0,1713,BDC_2432_3225288,00.html

Spacecraft built to crash

Ball Aerospace product set to ship out this month

By Todd Neff
The Daily Camera
October 2, 2004

NASA's Deep Impact spacecraft was a long way from the Tempel 1 comet on
Friday.

In a clean, gymnasium-sized room in Boulder, a dozen or so bundles of
wire snaked from a phalanx of computers to the elevator-sized craft. It
was in the middle of a 30-hour test, simulating the mission's critical
moments.

For all the spacecraft knew, it was July 3, 2005, and it was 80 million
miles from Earth, just before an Independence Day bash with a comet that
could unlock secrets of the solar system.

A team of up to 300 Ball Aerospace and Technologies Corp. employees have
spent the past 4 1/2 years building the $300 million Deep Impact for
NASA. The mission culminates when an 800-pound module from the craft
blasts into the comet's surface at a speed that will create a crater the
size of Folsom Field.

Deep Impact is scheduled to launch Dec. 30 and ships out for Cape
Canaveral, Fla., at the end of the month.

Success will break new ground: It would be the first look ever into the
core of a comet.

Comets wander about in odd orbits around the sun - Tempel 1 passes
through every five-and-a-half years - leaving behind their trademark
trails.

They are believed to be remnants of the solar system's earliest days
about 4.5 billion years ago. Donald Hampton, a Ball Aerospace instrument
system engineer who has been on the Deep Impact project from the outset,
called them "sort of the crumbs of the solar system's formation."

"From the scientific perspective, if we can look inside a comet, we can
look back in time," he said.

Thanks to their tails, scientists have an idea of what makes up a
comet's surface. Spectrographic analysis can identify a material based
on how it reflects light. Further, NASA's Stardust spacecraft is headed
back to Earth after collecting tail dust from the Wild 2 comet on Jan.
2, 2004.

But scientists suspect millennia of freezing and cooking through space
alters a comet's shell. What's inside is assumed to be more pristine,
and remains a mystery.

Deep Impact is going to crack it the hard way.

It's not entirely a suicide mission. Deep Impact is two spacecrafts in
one - "Impactor" is nestled into "Flyby" like a Russian stacking doll,
as Monte Henderson, Ball Aerospace's deputy program manager for Deep
Impact, put it. Here's how it will work:

After six months of travel, Deep Impact will track the comet by flying a
safe distance ahead of it. Then the craft will slow down a bit - to
about 23,000 mph slower than the comet, which is moving at roughly
triple that speed. The effect would be similar to a small car hitting
the brakes and pulling in front of a Mack truck, Hampton said.

On July 3, when it's about 800,000 miles from the Tempel 1, the
800-pound Impactor spacecraft will separate from Flyby and aim for a
bright spot on the comet, which is critical for the quality of
long-distance imagery of the impact. Flyby will move aside, giving the
comet a 300-mile berth.

Packed with 220 pounds of copper, Impactor's purpose in life is to smash
a several-stories deep, football field-sized crater into the comet,
which is roughly 4 miles long by 2 miles wide. But it's far more
intelligent than a flying anvil, capable of correcting its course and
outfitted with a science camera.

Given the distance - it would take 15 minutes for radio waves to make
the round-trip to mission control - Deep Impact must handle the
complexities of steering the small craft into a well-illuminated spot on
the comet on its own. Programming such intelligence was one of the
mission's toughest challenges, said Harold Reitsema, Ball Aerospace's
director of space sciences advanced programs.

A one-year launch delay was largely caused by Ball Aerospace's need for
more time to work on the computers.

Tom Bank, the mission systems engineer, likened the challenge of the
final 24 hours to hitting a charcoal briquette with a pellet from a
distance of six miles.

The impact with Tempel 1 will vaporize Impactor, but the mother ship
will immediately gather data from the explosive impact with an infrared
spectrometer and two telescopes.

Still, there's a good chance Flyby won't survive long. Thirteen minutes
after collecting the data, it must pass through the comet's tail.

Because even tiny particles have ballistic impact at such speeds, Deep
Impact scientists are relaying the most important information to Earth
during that short window. Meanwhile, both the Hubble and the Spitzer
space telescopes will train their gazes onto the fireworks, as will
several Earth-bound telescopes.

If it survives, Flyby will continue to gather data from deep space.

"We'll just have to hope our baby gets through it," Bank said.

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:
http://rockymountainnews.com/drmn/local/article/0,1299,DRMN_15_3225064,00.html

A shot in the dark

Scientists to target Comet Tempel 1 with space probe

By Jim Erickson
Rocky Mountain News
October 2, 2004

BOULDER - Imagine firing a BB gun at a charcoal briquette six miles away.

Now imagine making that shot at night, your gun holds just one BB and
there's $300 million riding on the outcome.

That's the kind of pressure-packed challenge that awaits Ball Aerospace
engineers when NASA's Deep Impact spacecraft attempts to blow an Invesco
Field-sized crater in the side of Comet Tempel 1 next July.

Ball built the probe for the space agency and is preparing to crate it
this month and truck it to Florida. Launch on a Delta 2 rocket from Cape
Canaveral is set for Dec. 30.

"We are losing a lot of sleep imagining things that could go wrong and
hoping we have the solutions," said Harold Reitsema, director of space
sciences advanced programs at Ball Aerospace & Technologies.

Other spacecraft have flown past comets and have dashed through the
cloud of gas and dust - called a coma - that boils off their icy cores.

But Deep Impact will be the first to bust through a comet's outer crust
and dredge up the pristine ices beneath.

The goal of the mission is to refine theories about the solar system's
formation by analyzing those ices, which have been in a deep freeze for
more than 4 billion years.

Comet Tempel 1 is a dark, peanut-shaped hunk of ice about five miles
long and nearly two miles wide. Its dirt-encrusted surface is blacker
than charcoal, Ball engineer Tom Bank said Friday as he held a
backyard-variety briquette between two fingers.

The Ford Explorer-sized Deep Impact spacecraft will travel six months to
reach Tempel 1. A day before the July 4 collision, the mother ship will
release an 825-pound "impactor" that will use onboard camera and
navigation systems to track down the comet like a smart bomb.

The impactor will be nearly half a million miles from the comet when it
begins its pursuit.

At a briefing for reporters on Friday, Bank said the task is roughly
equivalent to hitting a charcoal briquette from a distance of six miles.

But for the Deep Impact mission to be a complete success, a bull's-eye
isn't good enough.

As the impactor closes in, half of the comet will be lit by the sun. The
craft will target the sunlit half so the mother ship, known as the flyby
spacecraft, can photograph the explosion and analyze the composition of
the icy debris thrown from the crater.

Ball engineers say there's a 90 percent probability that the impactor
will hit Tempel 1's sunlit side.

"Once we're in that final trajectory through the coma, we'll just have
to cross our fingers and hope for the best," Bank said.

About a year ago, Deep Impact's three computers were plagued with more
than two dozen bugs that had the project's lead scientist, University of
Maryland astronomer Michael A'Hearn, on edge.

"I view the spacecraft computer as the biggest risk at the moment. The
problems are big, fixing them is expensive and we can't fly without
fixing them,"

A'Hearn said last November.

Since then, the Ball team has "found and solved all the bugs in the
computers" while remaining on budget, deputy program manager Monte
Henderson said Friday. "We have a rock-solid computer system," he said.

A'Hearn said he's sleeping much better lately.

"A month or two ago I began to have confidence that we had solved all
the problems that needed to be solved," he said. "So I think we're
actually in very good shape now."

Deep Impact will collide with Tempel 1 at 22,300 mph, ejecting a cloud
of ice, dust and gas that will significantly brighten the comet's
appearance from Earth.

The Earth-orbiting Hubble and Spitzer telescopes will be trained on
Tempel 1 that night, looking for the impact flash.

Normally, Tempel 1 cannot be seen with the naked eye. But it might be
visible without a telescope or binoculars after the July 4 collision,
A'Hearn said.

"It is conceivable that it could get up to naked-eye brightness," he
said. "I wouldn't go so far as to say it's probable, but it's possible."

More than 300 Ball Aerospace employees worked on the Deep Impact
project. The Ball portion of the $300 million mission was about $158
million.
Received on Sun 03 Oct 2004 04:54:21 PM PDT