European Space Agency picks site for comet landing

SCIENTISTS pick the spot to attempt the first-ever landing on a comet. And it won’t be easy, with the cliff and boulder-ridden comet travelling at nearly 60,000km/h.

The European Space Agency's Rosetta probe will release a robot lab called Philae in an audacious bid to land on speeding comet 67P/Churyumov-Gerasimenko. Picture: ESA

THE European Space Agency has unveiled the spot in deep space where it will attempt mankind’s first-ever landing on a comet, and “J” marks the spot.

The landing site is one of five that the ESA short-listed after its Rosetta spacecraft met up with rubber duck-shaped Comet 67P/Churyumov-Gerasimenko in August, following a marathon chase.

The comet is currently travelling at more than 59,000 km/h.

Codenamed “J”, the site offers the best chance for a safe landing on an exceptionally difficult target, while also offering conditions for meeting scientific goals, ESA said.

“The comet is a beautiful but dramatic world — it is scientifically exciting, but its shape makes it operationally challenging,” said Stephan Ulamec, in charge of the landing.

How @philae2014 will study the surface of #67P at site J: http://t.co/gMyo2C9Qo0

— ESA Rosetta Mission (@ESA_Rosetta) September 15, 2014

On November 11, Rosetta is scheduled to let down a robot lab called Philae to carry out experiments on the comet’s surface that scientists hope will shed light on the origins of these icy bodies — enigmatic voyagers born along with the Solar System itself.

Gently descending from a height of 10km, the 100-kg lab will use harpoons to anchor itself and then drive screws into the surface for better grip.

Its experiments will include drilling up to 30cm into the comet to extract pristine material for onboard chemical analysis.

Mission scientists had scrutinised five potential sites, named A, B, C, I and J, vetting each for the scientific return they offered, as well as landing risks and the amount of light available from the Sun for Philae’s solar cells.

Comet “67P” comprises two lobes joined by a narrow neck, making it resemble a rubber duck -- though one that is pitch black, darker even than charcoal.

Three of the candidate sites were on the smaller lobe, or head of the “duck”, and two on the larger lobe, or body. The oval-shaped landing site called “J” is roughly where the duck’s forehead would be; a backup site, “C”, is on the larger lobe.

Comets have in the past been considered iconic portents of good or evil. Doomed to orbit the Sun, their outer layers are stripped by solar heat as they draw nearer, leaving a trail of dust and ice crystals that is reflected in sunlight and looks like a tail viewed from Earth.

Astrophysicists say they are balls of ancient ice and dust left from the building of the Solar System some 4.6 billion years ago.

This cosmic rubble is essentially a time capsule -- the oldest, least-touched material in our stellar neighbourhood -- and understanding them may advance knowledge of how Earth came to bear life.

.@Philae2014 here’s some suggestions on what to pack :) http://t.co/uxROb5vIDE pic.twitter.com/XvUc4fEczZ

— ESA Rosetta Mission (@ESA_Rosetta) September 15, 2014

Water and molecules providing the building blocks for life came from comets that whacked into the fledgling planet at a time when the Solar System was a shooting gallery, according to one theory.

Jean-Pierre Bibring, lead Philae scientist, said mission managers were initially dismayed when the weird shape -- two blobs joined by a neck -- hoved into view as Rosetta raced towards the target in July.

Conceived two decades ago, the mission had broadly expected a rounded, “potato-shaped” object which would have made a landing far easier, Bibring said at a press conference.

“We were very scared at the beginning,” Bibring said.

Weeks of further work showed “reachable areas” where a landing could be made amid a jagged topography of cliffs, slopes, boulders and indentations.

Confirmation of the November 11 landing date is expected on September 26. ESA said it would also stage a competition for naming the site.

Rosetta, now looping around the comet at an altitude of 30 km, is equipped with 11 cameras and sensors that have already provided astonishing material.

But some of the biggest discoveries could be made by the 10 instruments aboard Philae, experts hope.

The four-km comet is on a 6.5-year Sun orbit.

Rosetta caught up with it after a six-billion-km trek that required four flybys of Earth and Mars, using the planets’ gravity as a slingshot to build up speed.

At their closest approach on August 13, 2015, the comet and Rosetta will be 185 million km from the Sun