ESA title
Science & Exploration

Rosetta’s blind date with asteroid Lutetia

15/06/2010 3535 views 3 likes
ESA / Science & Exploration / Space Science / Rosetta

ESA’s comet-chaser Rosetta is heading for a blind date with asteroid Lutetia. Rosetta does not yet know what Lutetia looks like up-close but beautiful or otherwise the two will meet on 10 July.

Like many first dates, Rosetta will meet Lutetia on a Saturday night, flying to within 3200 km of the space rock. Rosetta started taking navigational sightings of Lutetia at the end of May so that ground controllers can determine any course corrections required to achieve their intended flyby distance.

The close pass will allow around 2 hours of good imaging. The spacecraft will instantly begin beaming the data back to Earth and the first pictures will be released later that evening.

Rosetta flew by asteroid Steins in 2008 and other space missions have encountered a handful of asteroids. Each asteroid has proven to be an individual and Lutetia is expected to continue the trend.

Rosetta encountered asteroid Steins in 2008
Rosetta encountered asteroid Steins in 2008

Although recent high resolution ground-based images have given some idea of the overall shape of Lutetia, we have no idea what it looks like in detail. Rosetta will tell us that. Orbiting in the main belt of asteroids between Mars and Jupiter, initially it was thought that Lutetia is around 95 km in diameter but only mildly elliptical. Recent estimates suggest 134 km, with a pronounced elongation. Rosetta will tell us for certain and will also investigate the composition of the asteroid, wherein lies another mystery.

By any measure, Lutetia is quite large. Planetary scientists believe that it is a primitive asteroid left on the shelf for billions of years because no planet consumed it as the Solar System formed. Indeed, most measurements appear to back this picture, making the asteroid out to be a ‘C-type’, which contains primitive compounds of carbon.

Rosetta's ultimate destination is Comet Churyumov-Gerasimenko
Rosetta's ultimate destination is Comet Churyumov-Gerasimenko

However, some measurements suggest that Lutetia is an ‘M-type’, which could mean there are metals in its surface. “If Lutetia is a metallic asteroid then we have found a real winner,” says Rita Schulz, ESA Rosetta Project Scientist.

That is because although metallic asteroids do exist, they are thought to be fragments of the metallic core of larger asteroids that have since been shattered into pieces. If Lutetia is made of metal or even contains large amounts of metal, Dr Schulz says that the traditional asteroid classification scheme will need rethinking. “C-class asteroids should not have metals on their surfaces,” she says.

Asteroid science stands to gain once this observational conundrum is resolved because Rosetta’s data will provide a valuable collection of ‘ground truths’ that can be used to resolve conflicting ground-based observations not just for Lutetia but for other asteroids as well.

Rosetta spacecraft
Rosetta spacecraft

For 36 hours around the moment of closest approach, Rosetta will be in almost continuous contact with the ground. The only breaks will come as Earth rotates and engineers have to switch from one tracking station to another.

Good contact is essential because the uncertainties in the asteroid’s position and shape may demand last minute fine-tuning to keep it centred in Rosetta’s instruments during the flyby. “The skeleton of the operation is in place, and we have the ability to update our plans at any time,” says Andrea Accomazzo, ESA Rosetta Spacecraft Operations Manager.

Stay in touch with the flyby as it happens by visiting the Rosetta blog.

Related Links

Science & Exploration

Notes for editors

22/09/2010 743 views 0 likes
Read
The students who tested the Rosetta model
Science & Exploration

ESA’s Rosetta comet-chaser goes LEGO®

22/09/2010 7504 views 3 likes
Read
Science & Exploration

Rosetta’s blind date with asteroid Lutetia

15/06/2010 3535 views 3 likes
Read
Anticyclone over the South Pacific
Science & Exploration

Swirling clouds over the South Pacific

16/11/2009 1860 views 0 likes
Read
Rosetta closes in on home for the last Earth swingby
Science & Exploration

Rosetta sees a living planet

13/11/2009 6830 views 7 likes
Read
Enabling & Support

Rosetta bound for outer Solar System after final Earth swin…

13/11/2009 3729 views 2 likes
Read
Rosetta darting across the night
Enabling & Support

Rosetta darting across the night

13/11/2009 2269 views 1 likes
Read
First view as Rosetta approaches home
Enabling & Support

First view of Earth as Rosetta approaches home

12/11/2009 15942 views 24 likes
Read
Enabling & Support

ESA spacecraft may help unravel cosmic mystery

12/11/2009 3201 views 16 likes
Read
Rosetta spacecraft
Enabling & Support

Rosetta approach on schedule

06/11/2009 3069 views 1 likes
Read
A. Accomazzo with Rosetta Flight Control Team during Steins encounter 2008
Enabling & Support

Follow Rosetta’s final Earth boost

04/11/2009 1813 views 2 likes
Read
Rosetta spacecraft
Enabling & Support

Rosetta lined up nicely for Earth approach

28/10/2009 1362 views 1 likes
Read
Rosetta spacecraft
Science & Exploration

Last visit home for ESA’s comet chaser

20/10/2009 2789 views 1 likes
Read