Rosetta Reaches Comet Lander Delivery Orbit

Rosetta & Philae at comet 67P. Credit: ESA–C. Carreau/ATG medialab

Rosetta & Philae at comet 67P. Credit: ESA–C. Carreau/ATG medialab

Europe’s Rosetta orbiter has reached the orbit from which it will dispatch the small Philae lander to touchdown on the “head” of a comet for the first time in human history.

Rosetta arrived at the planned lander delivery orbit earlier today, Oct. 31, after mission controllers commanded the probe to fire its maneuvering thrusters at 02:09:55 UTC (03:09:55 CET) for a duration of 90 seconds.

An analysis by the Flight Dynamics team confirmed the success of the thruster maneuver in imparting a delta-v—change in speed—of 9.3 cm/sec.

The maneuver also raised Rosetta’s orbit to an altitude of 30 kilometers above the surface of comet 67P/Churyumov–Gerasimenko, which it will maintain until the planned touchdown on Nov. 12 at a spot currently dubbed “Site J.”

Rosetta had swooped down to within 8 to 10 kilometers of the comet’s surface in recent weeks to gather the high-resolution imagery and spectral data required to choose a safe and scientifically interesting landing site for Philae.

Four-image NAVCAM photo mosaic of Comet 67P/C-G taken on 15 October 2014, from a distance of 9.9 km from the centre of the comet, showing a portion of its ‘head’ lobe.  Credits: ESA/Rosetta/NAVCAM/Ken Kremer -kenkremer.com/Marco Di Lorenzo

Four-image NAVCAM photo mosaic of Comet 67P/C-G taken on 15 October 2014, from a distance of 9.9 km from the centre of the comet, showing a portion of its ‘head’ lobe. Credits: ESA/Rosetta/NAVCAM/Ken Kremer -kenkremer.com/Marco Di Lorenzo

Today’s maneuver “was the second and final of two ‘deterministic’ (i.e. direction and thrust are prepared in advance) manoeuvres that moved Rosetta onto the planned lander delivery orbit, now at a height of about 30 km, which will be maintained right up until the pre-delivery maneuver at two hours before separation at 08:35 UTC (09:35 CET) on the morning of 12 November,” said ESA in a statement.

The team may conduct some additional tweaking burns between now and touchdown day.

According to mission scientist Matt Taylor, Rosetta will never again orbit so close to the surface of comet 67P/C-G during the remainder of the mission.

“From now on, the closest distances we will achieve will be via flybys to provide the science instruments on the orbiter the closest look at the comet,” said Taylor in a statement.

Watch this ESA YouTube animation explaining Rosetta’s planned orbit trajectory maneuvers to deploy Philae:

Site J is located on the smaller of the two “lobes” of the utterly bizarre comet and is shown in the high-res ESA mosaic herein. The touchdown zone is circled and is approximately 500 meters in diameter.

The two image mosaic of Philae’s primary landing site was taken by the OSIRIS narrow-angle camera on Sept. 14, 2014, from a distance of 30 kilometers. The image is about 1 km across.

Following a thorough science, engineering, and hazard assessment of the merits of Site J, the European Space Agency (ESA) gave the green light in mid-October for Rosetta to deploy the Philae lander to the primary site on the “head” of Comet 67P/Churyumov–Gerasimenko as the location for humankind’s first attempt to touchdown on a comet.

Philae's primary landing site from 30 km. Close-up of the region containing Philae’s primary landing site J, which is located on the ‘head’ of Comet 67P/Churyumov–Gerasimenko. The mosaic comprises two images taken by Rosetta’s OSIRIS narrow-angle camera on 14 September 2014 from a distance of about 30 km. The image scale is 0.5 m/pixel. The circle is centred on the landing site and is approximately 500 m in diameter. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Philae’s primary landing site from 30 km. Close-up of the region containing Philae’s primary landing site J, which is located on the “head” of Comet 67P/Churyumov–Gerasimenko. The mosaic comprises two images taken by Rosetta’s OSIRIS narrow-angle camera on 14 September 2014 from a distance of about 30 km. The image scale is 0.5 m/pixel. The circle is centred on the landing site and is approximately 500 m in diameter. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Rosetta was designed and built by ESA and already made history when it became the first probe from Earth to orbit a comet.

Since rendezvousing with the comet on Aug. 6, 2014, after a decade-long chase of over 6.4 billion kilometers (4 billion miles), a top-priority task for the science and engineering team leading Rosetta has been “Finding a landing strip” for the Philae comet lander.

Stay tuned here for continuing developments.

Ken Kremer

 

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Jets are blasting from the active neck of comet 67P/Churyumov-Gerasimenko in this four-image photo mosaic comprising images taken on 26 September 2014 by the European Space Agency’s Rosetta spacecraft at a distance of  26.3 kilometers (16 miles) from the center of the comet.  See the montage ot four individual navcam images below.  Credit: ESA/Rosetta/NAVCAM/Marco Di Lorenzo/Ken Kremer – kenkremer.com

Jets are blasting from the active neck of comet 67P/Churyumov-Gerasimenko in this four-image photo mosaic comprising images taken on 26 September 2014 by the European Space Agency’s Rosetta spacecraft at a distance of 26.3 kilometers (16 miles) from the center of the comet. See the montage ot four individual navcam images below. Credit: ESA/Rosetta/NAVCAM/Marco Di Lorenzo/Ken Kremer – kenkremer.com

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