Rosetta and Philae: Landing first probe on a comet would be a staggering technical achievement

Rosetta and Philae: Landing first probe on a comet would be a staggering technical achievement

Above: A model of the lander being carried by the Rosetta Probe at the Cite De Espace in Toulouse.

Image Credit: Chris O’Brien

If things suddenly get quiet in Europe over the next couple of days, it’s because people across this continent are stopping to watch an historic achievement that’s been 10 years in the making.

Tomorrow, around 4:34 p.m. Central European Time (7:34 a.m. on the west coast of the U.S.), having left the Rosetta spaceship several hours earlier, the Philae robotic lander should touch down on the Comet 67P/Churyumov-Gerasimenko. It would be the first time a probe built by humans has landed on a comet.

Even
in an age of massive computing power, and wondrous feats of engineering, successfully hitting the high-velocity comet after launching in 2004 is a staggering technical milestone. Design of the Rosetta began in the 1990s. And the probe managed to get into orbit hundreds of millions of kilometers away despite having less computer processing power than your iPhone.

But Rosetta is about more than just technology. In getting this far, Rosetta has the potential to connect us to some of the central mysteries of the universe. One of the questions Rosetta set out to answer: Is it possible that a comet that crashed to Earth millions of years ago carried with it the seeds that allowed life to begin here?

“Comets should be studied because they carry matter present at the beginning of the solar system,” said Philippe Gaudon, head of the Rosetta project at the French space agency
CNES
. “They have important molecules that could help us understand the beginning of life.”

Rosetta is actually a project of the European Space Agency, with many other space agencies such as CNES and NASA collaborating. I saw Gaudon speak back in September at a Space meetup in Toulouse, where I live now. Toulouse is one of Europe’s space hubs, in part because space and aeronautics giant Airbus is based here. The meetup was held at Cite de Espace, a space museum located on the edge of town.

When Gaudon spoke, Rosetta mania was in full swing. The spacecraft had entered orbit around the comet, also a first. And now it was evaluating places where the probe could land.

The spacecraft was launched in March 2004 from Guiana Space Centre in Kourou, French Guiana. To get into orbit, the spacecraft followed an incredibly complex trajectory using gravity to slingshot around Earth and Mars several times as it swung further and further out into space:

Since getting into a 10 km orbit, Rosetta has been sending back information to allow the ESA to figure out where to land Philae on the comet, which has an odd shape, temperatures lower than -50 degrees Celsius, and craters and valleys. The stickers on the model below represent sites that were considered for the landing.

A model of the Comet 67P/Churyumov-Gerasimenko.

Above: A
model of the Comet 67P/Churyumov-Gerasimenko.

Now that a location has been selected, the Philae is ready to make history. But even now, after a decade, success is far from guaranteed. At 9:30 a.m. CET, Philae will be pushed out of Rosetta to drift down to the comet below. Once it separates, ESA has no control over the lander.

When it gets to the surface, it will fire two harpoons to anchor it. But either Philae will land upright, and begin to transmit data, or it will land awkwardly, tumble over or crash.

“We cannot abort and try again if we are unlucky,” Gaudon said.

Photo of the coment taken from
the Rosetta spacecraft in orbit.

Above: Photo of the comet taken from the Rosetta spacecraft in orbit.

Image Credit: European Space Agency

If it lands correctly, Philae will take an image of the landing site as well as a panoramic photo using its seven cameras. With the comet 500 million km from Earth, it will take an hour for the photos to arrive.

Then the work begins. Philae’s mission is to measure the density of thermal properties of the surface, its gravity, any gases being emitted, and other things. The probe will also use its drill to bore into the comet, scoop up a sample, and analyze it.

For all this work, if things go right, Philae has a lifespan of 65 hours. Less than three days. Then its battery is expected to give out, so there is some hope it can be recharged or extended. Rosetta will continue to orbit the comet until some time next year.

If
you want to watch the drama unfold, you can catch the ESA Rosetta livestream here:

If you’re in the Bay Area, you can also join the Long Now Foundation tomorrow at the Chabot Space Center to watch the livestream starting at 6 a.m. local time. The Rosetta probe is carrying one of Long Now’s Rosetta disks, a “micro-etched, nickel disk meant to last thousands of years that houses an archive of human languages so that future.”