[meteorite-list] Rosetta: 100 Days To Wake-Up

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 11 Oct 2013 14:51:00 -0700 (PDT)
Message-ID: <201310112151.r9BLp1I8027573_at_zagami.jpl.nasa.gov>

http://sci.esa.int/rosetta/53055-rosetta-100-days-to-wake-up/

Rosetta: 100 days to wake-up
European Space Agency
11 October 2013

ESA's comet-chasing mission Rosetta will wake up in 100 days' time from
deep-space hibernation to reach the destination it has been cruising towards
for a decade.

Comets are the primitive building blocks of the Solar System and the likely
source of much of Earth's water, perhaps even delivering to Earth the
ingredients that helped life evolve. By studying the nature of a comet
close-up with an orbiter and lander, Rosetta will enable scientists to
learn more about the role of comets in the evolution of the Solar System.

Rosetta was launched on 2 March 2004, and through a complex series of
flybys - three times past Earth and once past Mars - set course to its
destination: comet 67P/Churyumov-Gerasimenko. It also flew by and imaged
two asteroids, Steins on 5 September 2008 and Lutetia on 10 July 2010.

In July 2011 the spacecraft was put into deep-space hibernation for the
coldest, most distant leg of the journey as it travelled some 800 million
kilometres from the Sun, close to the orbit of Jupiter. The spacecraft
was oriented so that its solar wings were facing the Sun to receive as
much sunlight as possible, and it was placed into a slow spin to maintain
stability.

Now, as both the comet and the spacecraft are on the return journey back
into the inner Solar System, the Rosetta team is preparing for the spacecraft
to wake up.

Rosetta's internal alarm clock is set for 10:00 GMT on 20 January 2014.

Once Rosetta wakes up, it will first warm up its navigation instruments
and then it must spin down to point its main antenna at Earth, to let
the ground team know it is still alive.

"We don't know exactly at what time Rosetta will make first contact with
Earth, but we don't expect it to be before about 17:45 GMT on the same
day," says Fred Jansen, ESA's Rosetta mission manager.

"We are very excited to have this important milestone in sight, but we
will be anxious to assess the health of the spacecraft after Rosetta has
spent nearly 10 years in space."

After wake-up, Rosetta will still be about 9 million km from the comet.
As it moves closer, the 11 instruments on the orbiter and 10 on the lander
will be recommissioned.

In early May, Rosetta will be 2 million km from its target, and towards
the end of May it will execute a major manoeuvre to line up for rendezvous
with the comet in August.

The first images of a distant 67P/Churyumov-Gerasimenko are expected in
May, which will dramatically improve calculations of the comet's position
and orbit.

Closer in, Rosetta will take thousands of images that will provide further
details of the comet's major landmarks, its rotation speed and spin axis
orientation.

Rosetta will also make important measurements of the comet's gravity,
mass and shape, and will make an initial assessment of its gaseous, dust-laden
atmosphere, or coma.

The spacecraft will also probe the plasma environment and analyse how
it interacts with the Sun's outer atmosphere, the solar wind.

After extensive mapping of the comet's surface during August and September,
a landing site for the mission's 100 kg Philae probe will be chosen. It
will be the first time that landing on a comet has ever been attempted.

Given the almost negligible gravity of the comet's 4 km-wide nucleus,
Philae will 'dock' with it using ice screws and harpoons to stop it from
rebounding back into space.

It will send back a panorama of its surroundings and very high-resolution
pictures of the surface and will perform on-the-spot analysis of the composition
of the ices and organic material. A drill will take samples from 20???30
cm below the surface, feeding them to Philae's laboratory for analysis.

"The focus of the mission then moves towards what we call the 'escort'
phase, whereby Rosetta will stay alongside the comet as it moves closer
to the Sun," notes Fred.

The comet will reach its closest distance to the Sun on 13 August 2015
at about 185 million km, roughly between the orbits of Earth and Mars.

As the comet hurtles through the inner Solar System at around 100 000
km/h, the relative speed between orbiter and comet will remain equivalent
to walking pace. During this 'escort' phase the orbiter will continue
to analyse dust and gas samples while monitoring the ever-changing conditions
on the surface as the comet warms up and its ices sublimate.

"This unique science period will reveal the dynamic evolution of the nucleus
as never seen before, allowing us to build up a thorough description of
all aspects of the comet, its local environment and revealing how it changes
even on a daily basis," says Matt Taylor, ESA's Rosetta project scientist.

Rosetta will follow the comet throughout the remainder of 2015, as it
heads away from the Sun and activity begins to subside.

"For the first time we will be able to analyse a comet over an extended
period of time ??? it is not just a flyby. This will give us a unique
insight into how a comet 'works' and ultimately help us to decipher the
role of comets in the formation of the Solar System," adds Matt.

For further information, please contact:

Markus Bauer
ESA Science and Robotic Exploration Communication Officer
Tel: +31 71 565 6799
Mob: +31 61 594 3 954
Email: markus.bauer at esa.int

Fred Jansen
ESA Rosetta mission manager
Email: fjansen at rssd.esa.int

Matt Taylor
ESA Rosetta project scientist
Email: matthew.taylor at esa.int
Received on Fri 11 Oct 2013 05:51:00 PM PDT