ESA Rosetta Comet Chaser catches up with comet 67/P today

After an epic, decade-long trek across the solar system, the European Space Agency's Rosetta spacecraft will finally catch up to its target comet early Wednesday (Aug. 6). If all goes according to plan, Rosetta will become the first probe ever to orbit a comet, and you can watch the historic rendezvous live online.

Rosetta is expected to meet up with Comet 67P/Churyumov-Gerasimenko at 4:45 a.m. EDT (0845 GMT) Wednesday, with a crucial 6.5-minute-long engine burn propelling the spacecraft into the comet's orbit.

You can watch a live webcast of all the action at ESA.int beginning at 4 a.m. EDT (0800 GMT), courtesy of the European Space Agency (ESA).

Once Rosetta is in the gravitational grip of the comet, the spacecraft will execute a series of triangular loops around the comet.

Each loop will be about 62 miles (100 kilometers) long and take a few days to complete, mission officials said.



Rosetta blasted off from French Guiana in March 2004. During its 4-billion-mile (6.4-billion-kilometer) chase, the spacecraft zoomed around Earth three times and Mars once for "gravity assists" that helped the spacecraft pick up speed. Rosetta also got up close and personal with two asteroids during its travels.

When Rosetta reached Jupiter's orbit in 2011, ESA engineers put the spacecraft into a deep-space slumber that lasted more than 2.5 years.

Rosetta woke up in January this year for the final phase of its journey to Comet 67P, which is about 2.5 miles (4 km) wide and takes roughly 6.5 years to complete one lap around the sun.

Rosetta has since performed a series of complex maneuvers to slow down and match the comet's pace.

Now, the probe is poised to enter the comet's orbit and travel with it around the sun. Rosetta is also carrying a lander called Philae that's expected to touch down on the comet in November to take samples and study the comet's surface and composition.

ESA Rosetta commissioning in final stages

Artist’s impression of the ESA Rosetta orbiter. 

Credit: ESA/ATG medialab

All of ESA Rosetta's 11 science instruments and the lander Philae have now been successfully switched on!

But the data are still being analysed to confirm the mission's readiness for science operations, so the commissioning period is not officially complete until those final reports from the instrument teams are in (this is expected to take place on 13 May, and we'll provide another update then).

The instrument commissioning period lasted for an intense six weeks, with each instrument assigned dedicated timeslots to be put through their paces.

ESA Rosetta lander Philae

Some of the instruments behaved a little erratically at first (who wouldn't after being woken up after a nearly three-year sleep), which required a few of the observations to be repeated towards the end of the commissioning period.

For example, see the most recent blog contribution from the RPC-ICA instrument team for the challenges they encountered.

Now all of the instruments have been successfully reactivated and the necessary measurements have been taken.

Some were also treated to software upgrades, read more about COSIMA's upgrade here, and MIDAS here.

The majority of instruments have since been switched back off until the science readiness reviews are complete and Rosetta is closer to comet 67P/CG, but OSIRIS and the spacecraft's NavCams continue to take images for navigation purposes.

OSIRIS is also taking lightcurve measurements to determine the comet's rotation period.

Final preparations are now being made for a series of rendezvous manoeuvres that will bring the spacecraft closer to the comet, ready for arriving at 67P/CG in August; as of today, there's just over 2 million kilometres to go.

A separate blog entry will be posted in the next week to outline in more detail these critical manoeuvres.