[meteorite-list] Rosetta Continues Into Its Full Science Phase

[Ron Baalke]

http://www.esa.int/Our_Activities/Operations/Rosetta_continues_into_its_full_science_phase

Rosetta Continues Into Its Full Science Phase
European Space Agency
November 19, 2014

With the Philae lander's mission complete, Rosetta will now continue its 
own extraordinary exploration, orbiting Comet 67P/Churymov-Gerasimenko 
during the coming year as the enigmatic body arcs ever closer to our Sun.

Last week, ESA's Rosetta spacecraft delivered its Philae lander to the 
surface of the comet for a dramatic touchdown.

The lander's planned mission ended after about 64 hours when its batteries 
ran out, but not before it delivered a full set of results that are now 
being analysed by scientists across Europe.

Rosetta's own mission is far from over and the spacecraft remains in excellent 
condition, with all of its systems and instruments performing as expected.

"With lander delivery complete, Rosetta will resume routine science observations 
and we will transition to the 'comet escort phase'," says Flight Director 
Andrea Accomazzo.

"This science-gathering phase will take us into next year as we go with 
the comet towards the Sun, passing perihelion, or closest approach, on 
13 August, at 186 million kilometres from our star."

On 16 November, the flight control team moved from the large Main Control 
Room at ESA's Space Operations Centre in Darmstadt, Germany, where critical 
operations during landing were performed, to a smaller Dedicated Control 
Room, from where the team normally flies the craft.

Since then, Rosetta has performed a series of manoeuvres, using its thrusters 
to begin optimising its orbit around the comet for the 11 scientific instruments.

"Additional burns planned for today, 22 and 26 November will further adjust 
the orbit to bring it up to about 30 km above the comet," says Sylvain 
Lodiot, Spacecraft Operations Manager.

>From next week, Rosetta's orbit will be selected and planned based on 
the needs of the scientific sensors. After arrival on 6 August, the orbit 
was designed to meet the lander's needs.

On 3 December, the craft will move down to height of 20 km for about 10 
days, after which it will return to 30 km.

With the landing performed, all future trajectories are designed purely 
with science as the driver, explained Laurence O'Rourke and Michael Küppers 
at the Rosetta Science Operations Centre near Madrid, Spain.

"The desire is to place the spacecraft as close as feasible to the comet 
before the activity becomes too high to maintain closed orbits," says 
Laurence.

"This 20 km orbit will be used by the science teams to map large parts 
of the nucleus at high resolution and to collect gas, dust and plasma 
at increasing activity."

Planning the science orbits involves two different trajectories: "preferred" 
and "high-activity". While the intention is always to fly the preferred 
path, Rosetta will move to the high-activity trajectory in the event the 
comet becomes too active as it heats up.

"This will allow science operations to continue besides the initial impact 
on science planning that such a move would entail," adds Michael.

"Science will now take front seat in this great mission. It's why we are 
there in the first place!" says Matt Taylor, Rosetta Project Scientist.

"The science teams have been working intensively over the last number 
of years with the science operations centre to prepare the dual planning 
for this phase."

When solar heat activates the frozen gases on and below the surface, outflowing 
gas and dust particles will create an atmosphere around the nucleus, known 
as the coma.

Rosetta will become the first spacecraft to witness at close quarters 
the development of a comet's coma and the subsequent tail streaming for 
millions of kilometres into space. Rosetta will then have to stay further 
from the comet to avoid the coma affecting its orbit.

In addition, as the comet nears the Sun, illumination on its surface is 
expected to increase. This may provide sufficient sunlight for the DLR-operated 
Philae lander, now in hibernation, to reactivate, although this is far 
from certain.

Early next year, Rosetta will be switched into a mode that allows it to 
listen periodically for beacon signals from the surface.