22 AUSTRALIAN SKY & TELESCOPE July 2017

ESA / AIG MEDIALAB / ROSETTA / NAVCAM TEAM

“Farewell, Rosetta. You’ve done the job.

That was space science at its best. Thank you.”

With those simple words from mission manager Patrick

Martin, the Rosetta effort was over. Mission complete. The

audacious European Space Agency project that had been

in flight for 12½ years ended on September 30, 2016, with

a controlled thump onto the surface of the comet it had

studied in exquisite detail. It was a poignant moment for

those of us who’d been involved for two decades or more.

But there was also a sense of relief. After countless hours

spent planning and executing how to put a spacecraft

in orbit around an irregularly shaped and unpredictably

Anatomy of a

COMET

Escorted around the Sun by Europe’s Rosetta spacecraft, Comet 67P/

Churyumov-Gerasimenko proved to be more complex than just a “dirty snowball”.

temperamental nucleus, we found ourselves with time to dig

deeply into the treasure trove of data that Rosetta and its

lander, Philae, had returned to us.

Rosetta wasn’t the first spacecraft to visit a comet (see table

at right), but those were all flyby missions. Rosetta was the

first comet rendezvous, escort and landing operation. Think of

those flybys as snapshots, while Rosetta was an HD movie.

The mission’s ‘big picture’ science goals were to understand

the origin of comets, the relationship between cometary and

interstellar material, and the implications of those results to

the origin of the Solar System. To do that, the team needed to

measure the large-scale properties of a comet’s nucleus, study

its surface, determine the chemical and dynamical properties

ROSETTA RESULTS by Joel Parker