[meteorite-list] Deep Impact Feared Lost

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 11 Sep 2013 08:42:32 -0700 (PDT)
Message-ID: <201309111542.r8BFgW3V023191_at_zagami.jpl.nasa.gov>

http://www.spaceflightnow.com/news/n1309/10deepimpact/
 
NASA's plucky Deep Impact probe feared lost
BY STEPHEN CLARK
SPACEFLIGHT NOW
September 10, 2013

Scientists fear NASA's comet-chasing Deep Impact spacecraft may be lost
in space after a software glitch cut off communications between the aging
space probe and befuddled engineers on Earth.
 
NASA last heard from the distant spacecraft on Aug. 8, and efforts to
restore contact with Deep Impact have produced no results. Engineers will
continue to uplink commands to the probe in an attempt to reestablish
communications, the agency said in a press release Tuesday.

Officials blame Deep Impact's problem on a software glitch, according
to Michael A'Hearn, the mission's principal investigator from the University
of Maryland in College Park.

"The problem was a software issue in having run the mission for many years
past its design lifetime," A'Hearn told Spaceflight Now. "This basically
caused an overflow in the on-board time, which in turn caused a continuous
cycle of rebooting the on-board computer."

About the size of a sports utility vehicle, the Deep Impact spacecraft
launched in January 2005 and reached comet Tempel 1 less than six months
later, deploying a copper impactor to slam into the comet's nucleus as
the Deep Impact mothership and telescopes studied material ejected from
the cosmic collision.

Mission controllers reshaped Deep Impact's course several times after
its primary mission ended, beginning an extended phase named EPOXI. placing
the probe on course to fly by comet Hartley 2 in November 2010. Since
the Hartley 2 encounter, Deep Impact used its high-resolution telescope
to make long-range observations of comets Garradd (C/2009 P1) and ISON.

A'Hearn posted a status update Sept. 3 on the mission's website announcing
the spacecraft's trouble, which occurred during Deep Impact's comet ISON
observing campaign. Deep Impact was storing data on ISON on-board the
spacecraft before beaming it back to Earth, A'Hearn said, so none of the
information has been recovered.

"The challenge is to understand the present state of the spacecraft and
how to communicate with it, a problem that the spacecraft team is studying
very hard," A'Hearn said.

In a story posted Sept. 5 on the Nature News blog, A'Hearn said engineers
are racing the clock because the probe could lose electrical power if
its solar panels are pointed away from the sun.

A'Hearn told Spaceflight Now on Tuesday engineers are not sure which way
Deep Impact is pointing or if it is spinning out of control.

"Since we don't have communication, we don't know whether it is tumbling
or not. It is correct that we don't have control, so it might be," A'Hearn
told Spaceflight Now.

Deep Impact has a steerable high-gain antenna, which requires precise
pointing toward Earth to connect with controllers. Two less capable
omnidirectional low-gain antennas are also aboard Deep Impact.

Built by Ball Aerospace and Technologies Corp., the Deep Impact spacecraft
was intended for a brief six-month primary mission. Since its launch
eight-and-a-half years ago, the probe has traveled about 4.7 billion miles,
according to NASA.

Deep Impact is running low on fuel, but NASA authorized a series of rocket
burns in 2011 and 2012 to alter the craft's trajectory and set up a potential
flyby of asteroid 2002 GT, a mystical object that regularly crosses paths
with Earth. It could be a target for future human expeditions and it has
a risk of one day colliding with Earth.

If Deep Impact makes it, the flyby with 2002 GT would occur in January
2020.
Received on Wed 11 Sep 2013 11:42:32 AM PDT