Rosetta closes in on Earth -- a second time (Forwarded)
- From: Andrew Yee <ayee@xxxxxxxxxxxxxxxxxxxxxx>
- Date: Fri, 9 Nov 2007 20:31:00 GMT
ESA News
http://www.esa.int
8 November 2007
Rosetta closes in on Earth -- a second time
ESA's comet chaser, Rosetta, is on its way to its second close encounter
with Earth on 13 November. The spacecraft's operators are leaving no
stones unturned to make sure Earth's gravity gives it the exact boost it
needs en route to its destination.
This month's Earth swing-by is Rosetta's third major step on its 10-year
journey to 67/P Churyumov-Gerasimenko. The trajectory correction manoeuvre
successfully performed last month prepared ESA's Comet Chaser for the
upcoming encounter. The spacecraft is now right on track to gain the right
amount of energy from Earth's gravity and save fuel later on.
Closest approach will take place on 13 November 2007 at 21:57 CET [2057
UTC], at which time Rosetta will speed past at 45 000 km/h (about 12.5
km/s) relative to Earth. At this time, Rosetta will be 5301 km above the
Pacific Ocean, south-west of Chile, at 63 deg 46' south and 74 deg 35'
west.
Why swing by Earth?
Swing-bys make use of the gravitational attraction of planets to modify a
spacecraft's trajectory and to gain the orbital energy needed to reach the
final target.
The first Earth swing-by took place on 4 March 2005. On 25 February 2007
Rosetta made its closest approach to Mars, to use its gravity. The
swing-by this month will be followed by the third and last swing-by, using
Earth's gravity, on 13 November 2009.
While the gravity-assist manoeuvre at Mars was needed to slow the
spacecraft down and head back towards the inner solar system, the second
Earth swing by will help Rosetta gain enough energy to reach the outer
Solar System through the asteroid belt and observe asteroid Steins, one of
its scientific targets. Rosetta will then head back to Earth for the last
planned swing-by in November 2009.
The increased energy from this Earth swing-by will help Rosetta cross the
asteroid belt for a second time, observe Lutetia (its second target
asteroid) and finally rendezvous with comet 67/P Churyumov-Gerasimenko.
The rendezvous will take place about 4 astronomical units or 600 million
km from the Sun, in 2014.
Intense activity coming up ...
During this Earth swing-by, the highest priority will be given to
spacecraft operations, as the manoeuvre is critical for the success of the
overall mission. In addition, during the incoming and outgoing tracks of
the swing-by, Rosetta will be under unfavourable solar illumination and
thus temperature conditions. This is why only very limited slots will be
available for the instruments to be used safely.
Despite this, a few experiments both on the orbiter and the Philae lander
will be activated for calibration, scientific measurements and imaging.
The observations are scheduled during and around the time of closest
approach, from 7 Nov, 01:00 CET [0000 UTC], to 20 Nov, 15:00 CET [1400
UTC].
Rosetta will first point to Earth to make observations of the atmosphere
and the magnetosphere, including a search for shooting stars from space.
It will image urban regions in Asia, Africa and Europe and then point to
the Moon and obtain spectra of the illuminated Moon. Flying away after
closest approach, Rosetta will image the Earth-Moon system from a
distance.
Rosetta will be controlled from ESA's Spacecraft Operations Centre (ESOC)
in Darmstadt, Germany
For more detail about Rosetta's spacecraft and scientific operations,
please read the Rosetta second Earth swing-by Q&A.
For the swing-by, the ESA Web portal is hosting a Rosetta swing-by blog
providing frequent updates, news and information direct from the Rosetta
Dedicated Control Room at ESOC.
Timeline of major activities
Times shown are ground event times in Central European Time, equivalent to
UTC (Coordinated Universal Time) + 1 hour
7 Nov
1:00 Start of observations of Earth's magnetosphere (to be continued
until 20 November)
13 Nov
1:00 Start of slew manoeuvre bringing the spacecraft into
'Earth-pointing' attitude
21:57 Closest approach to Earth
22:02 Start of slew manoeuvre bringing the spacecraft into
'Moon-pointing' attitude
23:00 Start of Moon imaging and observations (to be continued until 20
November)
14 November
1:45 Start of first Rosetta data down-link to Earth. There will be a
downlink slot each day until 22 November
09:00 Images start appearing on ESA web site
11:02 End of Moon pointing slot
15 November
1:00 Images of the Earth-Moon system from distance
For more information:
Gerhard Schwehm, ESA Rosetta Mission Manager
Email: Gerhard.Schwehm @ esa.int
Andrea Accomazzo, ESA Rosetta Spacecraft Operations Manager
Email: Andrea.Accomazzo @ esa.int
Rita Schulz, ESA Rosetta Project Scientist
Email: Rita.Schulz @ esa.int
[NOTE: Images and weblinks supporting this release are available at
http://www.esa.int/esaCP/SEMC20VOM8F_index_1.html ]
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