This story was updated at 5:35 a.m.
EDT.
PASADENA -- The Fourth of July began with a
bang here early Monday morning as NASA's Deep Impact mission collided with
history.
"There is a comet up in the sky
wondering, what in the heck just happened," said JPL director Charles Elachi during a post-collision press conference.
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This image shows the initial ejecta that resulted when NASA's Deep Impact probe collided with comet Tempel 1 at 10:52 p.m. Pacific time, July 3 (1:52 a.m. Eastern time, July 4). It was taken by the spacecraft's medium-resolution camera 16 seconds after impact. Credit: NASA/JPL-Caltech/UMD. Click to enlarge.
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The $333 million mission to crash an
820-pound (371-kilogram) Impactor probe into the avocado-shaped
Comet Tempel 1 and record the event via a Flyby mothership was a complete success. Mission
managers at NASA's Jet Propulsion Laboratory (JPL) said the probe,
jettisoned almost 24-hours earlier from Flyby, collided with the comet at 1:52
a.m. EDT (0552 GMT). The impact was confirmed by flight controllers on the ground at 1:57 a.m. EDT.
The control room erupted in cheers
as the first images from Impactor's perilous approach
to Tempel 1 were transmitted to Earth via the Flyby
spacecraft.
"I can't believe they're paying us
to have this much fun," exclaimed Don Yeomans, a Deep
Impact mission co-investigator for JPL. "The impact was bigger than what I
expected."
Deep Impact scientists said they
have already received some data from orbital and ground-based observatories
that provided additional vantage points to the impact.
"We're getting a lot of
results," said Michael A'Hearn, Deep Impact
principle scientist from the University
of Maryland. "They
observed a brightness increase of about two magnitudes, and a few telescopes
reported big increases in the emission lines."
Good craftsmanship
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The Hubble Space Telescope captured the Deep Impact collision with Comet Temple 1. Top is before the collision, the bottom image is after. Image Credit: HST
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Impactor ended its almost six-month mission
by successfully transmitting back images of the comet as it raced at a speed of
44,000 miles per hour into the surface of Tempel 1.
That initial success, however was eclipsed when Flyby successfully transmitted
back the first image of the Impactor's collision with
Tempel 1.
"I just can't believe it. It's
absolutely incredible," said Alice Phinney, Lead
Mechanical Design Engineer for the Impactor at Ball
Aerospace in Boulder, Colorado. She was one of over 600 company
colleagues and friends that gathered at Boulder's
Fiske Planetarium.
Phinney told SPACE.com that she worked on the Impactor
that smashed into the comet for some two years. One of her key jobs was
maximizing the use of copper in the Impactor design.
The task was not as straight-forward
as it would seem. "There were a lot of assumptions. Scientists were all over
the map," Phinney said regarding the overall
composition of Comet Tempel 1.
"That's why I love engineering...at
some point you've got to make a decision." The Impactor
"worked like a champ," Phinney said.
Atop the Fiske
Planetarium, rooftop observers using a 24-inch telescope reported seeing a
brightness of the comet at impact.
"This is the biggest thing
that's happened for the company," said Roz
Brown, a spokeswoman for Ball Aerospace, which built the Deep Impact
spacecraft. "This is huge for us."
Back to work
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One of the first pictures of comet Tempel 1
from the Deep Impact mothership, as NASA scientists
saw it. Credit: NASA/JPL. Click to enlarge.
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After a brief celebration, Deep
Impact flight controllers gradually called mission engineers and scientists
back to their posts. Impactor's mission may now be
finished, but its Flyby mothership still has images
to deliver and more observations to make of Tempel
1's surface.
"We still have a Flyby spacecraft
which is still collecting data, so we have to stay focused," JPL director
Charles Elachi said. "I think it was worth every cent
we spent on it."
The Deep Impact was reported as
healthy after managing to track Impactor's collision
with Tempel 1 down to about 50 meters, then turn its imaging lenses away from the comet to guard
them from debris as the spacecraft passed underneath the nucleus.
In the two hours preceding the
collision Impactor was basically on its own, as was
the Flyby spaceship, Yeomans explained earlier in the
day. Within that time period, Impactor performed
three course corrections. Impactor's first targeting
maneuver, or course correction, was a 21.5-second burn that occurred about 90
minutes prior to impact.
"As soon as the first [trajectory
maneuver] went off on the Impactor and it worked
fine the confidence just went sky high," Deep Impact's deputy project manager
Kuyer Patel told SPACE.com.
"We had a full spacecraft that had just been released on its own 24 hours
ago and it had three sets of thrusters on it, one for attitude control and one
for maneuvers. All of that got checked out right after its release so this was
the only unknown left, so as soon as that first
trajectory change happened, everyone was just confident at that point."
The second course correction took place about
35 minutes prior to impact and the final at 12-and-a-half minutes.
"It takes 7/ ½ minutes for the
signal to get back to Earth, so you can't joystick this thing," Yeoman said.
"You have to rely on the fact that the Impactor is a
smart spacecraft as is the Flyby spacecraft. So you have to build in the
intelligence ahead of time and let it do its thing."
Smooth autonomy
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This image from NASA TV shows the nucleus of comet Tempel
1 from Deep Impact's flyby's high-resolution imager. Credit: NASA/JPL. Click
to enlarge.
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For mission managers, the
spacecraft's automated controls worked perfectly. Such success will be repeated
in the future, Yeomans said.
"This isn't the first time auto-navigation
was used," Yeomans explained. "It was actually a
back-up system for the Deep Space 1 mission that flew past Comet Borrelly back in 2001. That was a checkout for a back-up
system that was not relied upon, but now, of course, we are indeed relying on
it. So that's a new wrinkle for this mission."
Also, Deep Impact's use of optical
navigation is something NASA has relied on for years.
"By using the onboard telescope
system to prove our knowledge of where the comet is not new," said Yeomans. "But it builds on what has been done in the last
several years in terms of 'smart' spacecraft. That is a trend, of course, to
get this small army of navigators on the ground down to where it is now just a
handful of folks."
Yeomans said he believed that it would take
about 12 hours from impact to download all of the events images.
"But it will take months, even
years, before all the science is even squeezed out of the data," said Yeomans. "Within the first six months the highlights will
be published, but there will be analyses going on for quite some time. It's not
just the spacecraft that is observing this comet. Chandra has observing in the
X-ray spectrum. Spitzer will be observing in the infrared. Hubble will be
observing in the visible."
Yeomans hoped that the success of Deep
Impact would lead to more ambitious missions. "The next step is to actually
rendezvous with a comet, orbit it, and then land and
do surface analysis," Yoemans said. "Which is what the Europeans expect to do with the Rosetta
spacecraft in 2014."
Ultimately, Yeomans
said that the most ambitious mission would be to land on a comet, take a sample
and return it for study in Earth-based laboratories. "There have been proposals
to do just that. Nothing funded," Yoemans said. "But
we're thinking that way."
SPACE.com Senior Space Writer
Leonard David contributed to this story from Boulder, Colorado.
Staff Writer Tariq Malik contributed to this story from New York City.
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