[meteorite-list] Rosetta's Pioneering Philae Comet Lander Reactivated

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 2 Apr 2014 11:32:29 -0700 (PDT)
Message-ID: <201404021832.s32IWTFj024543_at_zagami.jpl.nasa.gov>

Rosetta's pioneering Philae comet lander reactivated
April 1, 2014

Since the Rosetta spacecraft emerged from hibernation in January, engineers
have checked the probe's systems and found them in good condition, according
to Andrea Accomazzo, Rosetta's spacecraft operations manager at the European
Space Agency.

Rosetta is heading toward an August rendezvous with Comet 67P/Churyumov-Gerasimenko,
an inner solar system comet that completes one circuit of the sun every
six-and-a-half years.

Ground teams started activating Rosetta's science instruments March 17,
successfully switching on the spacecraft's primary science camera, ultraviolet
spectrometer, and a plasma sensor suite to study the environment around
the comet.

On Friday, the $1.7 billion mission's German-built Philae lander woke
up and radioed Earth.

"Philae is operational and ready for the next few months," said Stephan
Ulamec, Philae project manager at DLR, the German space agency.

Philae will be ejected from the Rosetta mothership in November to latch
itself onto the comet's icy surface with harpoons and screws. The lander
has its own suite of science instrumentation to take the first-ever photos
and measurements from a comet's surface.

Engineers plan a four-week commissioning phase for Philae to check on
its health and activate the lander's 10 instruments.

"We will analyse this data thoroughly, so we can find out whether Philae
has survived the long flight and hibernation intact," Ulamec said in a
DLR press release.

Before Friday, controllers last received data from Philae on June 8, 2011,
when Rosetta entered hibernation. Since Rosetta woke up in January, the
craft sent back preliminary temperature measurements from Philae.

The first data packets from Philae arrived on Earth at 1440 GMT (10:40
a.m. EDT) Friday through a NASA tracking antenna in California, which
fed the telemetry to the lander's control center in Germany.

Philae's 10 instruments will be activated and tested throughout April.
By May, all of the mission's science payloads will be commissioned, including
the 11 instruments aboard the Rosetta mothership.

So far, Rosetta's scientific camera has finished its round of testing
since the spacecraft woke up in January. The Optical, Spectroscopic and
Infrared Remote Imaging System, developed by the Max Planck Institute
for Solar System Research in Germany, took the first pictures of the comet
since hibernation on March 20 and 21.

"Finally seeing our target after a 10 year journey through space is an
incredible feeling," said Holger Sierks, OSIRIS principal investigator
at the Max Planck Institute. "These first images taken from such a huge
distance show us that OSIRIS is ready for the upcoming adventure."

Churyumov-Gerasimenko was about 5 million kilometers, or 3.1 million miles,
from Rosetta when the pictures were taken earlier this month.

The rest of Rosetta's instruments are still being tested.

A series of engine burns in May will adjust Rosetta's course toward the
comet, burning much of the spacecraft's remaining fuel. Rosetta is now
on a trajectory to miss the comet by approximately 50,000 kilometers,
or about 31,000 miles.

The trajectory correction maneuvers in May will guide Rosetta within 100
kilometers, or about 60 miles, of Churyumov-Gerasimenko by the first week
of August, according to ESA.

Officials have penciled in Philae's landing on Churyumov-Gerasimenko for
Nov. 11, but the date could be adjusted a few days based on the probe's
landing site and conditions around the comet.

Philae will operate for at least two days on the comet, and it carries
solar arrays to recharge its battery if comet's unpredictable dust environment

"Landing on the surface is the cherry on the icing on the cake for the
Rosetta mission on top of all the great science that will be done by the
orbiter in 2014 and 2015," said Matt Taylor, Rosetta's project scientist,
in a blog post on ESA's website. "A good chunk of this year will be spent
identifying where we will land, but also taking vital measurements of
the comet before it becomes highly active. No one has ever attempted this
before and we are very excited about the challenge!"

One of Philae's instruments will drill into the comet's surface, collect
a sample and feed it into an on-board oven for analysis.

Scientists do not know what environment awaits Rosetta and Philae at the

Controllers will cautiously approach Churyumov-Gerasimenko with Rosetta,
taking cues on how to navigate around the comet based on the amount of
debris observed by the spacecraft's two main cameras.

The flexible approach allows officials to keep a safe distance from the
comet if the ice and dust are deemed too hazardous.

Rosetta will follow the comet for at least a year while it makes its closest
approach to the sun, watching Churyumov-Gerasimenko "wake up" as sunlight
and heating trigger the comet's volatile jets of water vapor and gas.

Scientists are eager to better understand comets because they may have
seeded Earth with water and the building blocks of life soon after the
genesis of the solar system.

"They are time capsules," said Mark McCaughrean, senior advisor in ESA's
science and robotic exploration directorate, in a press conference in
December. "They are remnants of the birth of the solar system. They go
back to the beginning of the solar system more than 4.6 billion years
Received on Wed 02 Apr 2014 02:32:29 PM PDT

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