Rosetta spacecraft’s last few days

After over 12 years Rosetta will be decommissioned by sending it down to impact with comet 67P/C-G.  This fate was decided as the comet is moving away from the sun, beyond the orbit of Jupiter and the solar panels will not generate enough power to keep the spacecraft operational.  Even “hibernation” is not a possibility as heaters are still required to keep the critical systems idling.  Hence mission control will send commands in the next few days such that on September 29th a series of maneuvers will send it on a impact trajectory with the comet.  As the comet’s gravity is rather weak (1/10,000 of Earth’s) it will most likely not be a fatal impact.  However the Rosetta will be instructed to shutdown upon contact with the surface in order not to “pollute” the deep space communication network with spurious and uncommanded signals.  This is expected to happen on September 30th 10:40 GMT.

So where is comet 67P/C-G?  Travelling towards the orbit of Jupiter, in constellation Virgo, opposite to the sun from Earth’s perspective.  Normally an event like this would be timed to be observable at night from Earth such that telescopes can gather scientific data.  But at apparent magnitude 20 (to compare, Pluto has a mean apparent magnitude of 15) it will be very difficult to observe.  And the impact is not expected to generate a large plume of dust.  Therefore it will be up to Rosetta to record and beam back to Earth as much data during the descent before shutting down for good.

Rosetta and comet 67P/C-G position on September 30th

Rosetta and comet 67P/C-G position on September 30th

Reference: ESA

Comet 67P/Churyumov–Gerasimenko – Can we see it?

First of all I want to congratulate the Rosetta team on their successful landing of Philae on the comet surface.  When you consider that the spacecraft was launched 10 years ago, it was essentially designed and assembled with 15-year-old technology.  Back then, digital cameras were just entering the market and the Palm III PDA was the mobile device everyone wanted.  In fact, much of the code running on Rosetta and Philae was developed after the aircraft was launched.

Presently 67P is located between Jupiter and Mars, on its swing towards the sun. To give you an idea how far out it’s located in the solar system, it takes over 28 minutes for radio communications from Rosetta to reach Earth.  Therefore if mission control sends a comment to Rosetta, the results are only known one hour later!

Location of comet 67P/Churyumov–Gerasimenko on November 13th, 2014

Location of comet 67P/Churyumov–Gerasimenko on November 13th, 2014 (Credit: ESA)

Starting in May 2015 67P will become visible to observers in the Northern Hemisphere, and will gradually brighten until achieving perihelion on August 13, 2015.  Because it does not venture very close to the sun, past observations indicate that it will only reach magnitude 11 at best; a challenge to backyard telescopes.

Better slew your observation by 9 degrees north, that’s where comet 141P/Machholz will be in the same constellation (Gemini) and at magnitude 8; a slightly brighter target.  And if you have no luck observing either comets or capturing them on photo, open cluster M35 is in the area.

Until then, you can follow Rosetta and Philae’s adventure on their blog: blogs.esa.int/rosetta/