On 10 July, the European Space Agency will webstream Rosetta's fly-by of Asteroid Lutetia in a two-part programme live from ESOC, ESA's European Space Operations Centre, Darmstadt, Germany.

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 radio the data back to Earth and the first pictures will be released later that evening. The webstream is available for embed/re-casting via our channel in Livestream.com:: http://www.livestream.com/eurospaceagency

Click on 'Full story' for details on how you can embed-re-cast the webstream in your website, personal home page, blog or other channel. -- Daniel

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The call for press has just gone out in the main ESA website. Full information and details on registering for the fly-by media event here at ESA/ESOC on 10 July 2010 are available here. -- DGS

 

 

 

 

 

Today, ESA's flight dynamics team compiled a fresh forecast on Rosetta's fly-by time and distance, based on analysis of last week's thruster burn and additional ground station data received from NASA's DSN network. The results? The closest approach is forecast to occur at a distance of 3169 km from Lutetia at a predicted time of 15:44:55.51 UTC (with a 3-sigma uncertainty of 7.43 seconds). -- Daniel

Rosetta Spacecraft Operations Manager Andrea Accomazzo just rang to confirm that this morning's trajectory correction manoeuvre is complete - post-burn telemetry from the spacecraft is being received via ESA's 35m station at New Norcia, Australia. We will now wait for the flight dynamics experts to perform an analysis. -- Daniel

The Rosetta team here at ESOC are preparing for a thruster burn tomorrow, 18 June, designed to manoeuvre the deep-space probe onto an altered trajectory that will take it to the desired fly-by point on 10 July (burn starts 08:24 CEST).

Now here's an interesting bit of space science: based on data gathered during this month's complex optical navigation campaign, the spacecraft is currently predicted to make closest approach at just 2639 km from Lutetia - quite a bit closer to the asteroid then the hoped-for 3160 km.

Closer would be better, don't you think? So why are the Rosetta team burning fuel to take the point of closest approach 526 km further away from the target?

It turns out that 2639 km would be too close - more details under 'Full story' -- Daniel 

Exploded view of Rosetta showing internal and external components. There are 24 10N thrusters mounted externally.

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A lovely little photo kicks off our Lutetia fly-by coverage! This first image of asteroid Lutetia was captured on 31 May 2010 by Rosetta's Navigation Camera A (there are two, 'NavCam A' and 'NavCam B') and was processed by the Flight Dynamics team here at ESOC, ESA's European Space Operations Centre, in Darmstadt, Germany.

(Click on 'Full story' for more details) -- Daniel

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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.

Full article in ESA web portal here.

On 10 July 2010, Rosetta will pass by asteroid (21) Lutetia, with closest approach predicted to take place at 15:44 UTC (17:44 CEST).

This will be the spacecraft's second asteroid encounter with an asteroid of the main asteroid belt between Mars and Jupiter.

Rosetta is expected to pass the asteroid with a relative velocity of 15 km/s at a minimum distance of 3160 km (all figures subject to change). The selected flyby strategy allows continuous observation of the asteroid before, during and after closest approach. Most of the scientific instruments on Rosetta will be switched on for investigations. Imaging and spectral observations will be obtained covering ultraviolet to sub-millimetre wavelengths. A number of in situ measurements will be made of the asteroid as well as of its direct environment.

The target, (21) Lutetia, is a large asteroid with an estimated diameter of about 95 km. It has been classified as either C-type or M-type, meaning that remote sensing observations have shown features that hint at characteristics of carbonaceous chondrite (a type of meteorite that contains organic chemicals and water), but also to a metallic surface composition. This contradiction makes (21) Lutetia an extraordinarily interesting object for close inspection from space.

More info to follow in the coming days here in the Rosetta Blog!

We reported earlier on the two-decade-old Earth Swingby Anomaly:

Since 1990, scientists and mission controllers at ESA and NASA have noticed that their spacecraft sometimes experience a strange variation in the amount of orbital energy they exchange with Earth during planetary swingbys. The unexplained variation is noticed as a tiny difference in speed gained or lost during the swingby when comparing that predicted by fundamental physics and that actually measured after the event.

Last week, after analysing the radiometric data gathered by ESA and NASA ground stations that tracked Rosetta during her successful 13 November swingby, ESA's Trevor Morley, the lead flight dynamics specialist on Rosetta, sent us a brief mail update. His report?

"For Rosetta's third and final Earth swingby, there was no anomaly."

(Access more details under 'Full story' below) -- Daniel

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Today, NASA's popular "Astronomy Picture of the Day" website features a cool image acquired by none other than our favourite comet chaser, Rosetta! 

Our NASA colleagues wrote:

"Goodbye Earth. Earlier this month, ESA's interplanetary Rosetta spacecraft zoomed past the Earth on its way back across the Solar System. Pictured above, Earth showed a bright crescent phase featuring the South Pole to the passing rocket ship. Launched from Earth in 2004, Rosetta used the gravity of the Earth to help propel it out past Mars and toward a 2014 rendezvous with Comet Churyumov-Gerasimenko. Last year, the robot spacecraft passed asteroid 2867 Steins, and next year it is scheduled to pass enigmatic asteroid 21 Lutetia. If all goes well, Rosetta will release a probe that will land on the 15-km diameter comet in 2014."

On behalf of the entire team working on Rosetta, 'Thanks guys!' -- Daniel

(Click on the image above to view the original version in ESA website.)

Stubbe Hviid, OSIRIS Operations Manager, has sent us a response to a comment made on this post:

"In the last pic, I'm wondering what the tiny dots are (multiple white and one black) : due to Osiris?, to data processing?, to objects above clouds? (X,Y) for the black at (760pxl/2048, 456pxl/1083) and for one white at (753/2048, 172/1083). At least the block dot is also present on the first pic."

Stubbe says that the white dots are caused by cosmic ray events. When the images were taken, the spacecraft was in open space (of course). This means that the spacecraft experiences the full effect of the solar wind and high energy particles. These high energy particles are detected by the CCD as light flashes. On the surface of the Earth, we normally do not see these cosmic ray events because the atmosphere shields us.

The white dots due to the cosmic ray events are completely normal. For example, the coronagraph of ESA's SOHO satellite regularly experiences a bakeout. With respect to SOHO bakeout, Stubbe added:

It is the same effect but a different kind of detector. OSIRIS also has the capability to 'bake out' the CCD (also called annealing). As a rather extreme example of this, here's an image we took of Comet Machholz back in 2005, during which Rosetta was caught in a Coronal Mass Ejection solar flare with a radiation level about 100 000 times higher than normal.

Note a comment left by J.M. Mondelo, who observed Rosetta on 12 November 2009 (thanks for the link and great pictures!). -- Daniel

Kristin wrote to us early on Saturday morning, 14 November.

During the night of 13/14 November, the team at ESA's Optical Ground Station, Tenerife, imaged Rosetta receding from Earth. The spacecraft's brightness was very low as they were looking at the non-illuminated side of the solar arrays; in contrast, during approach, sunlight was reflected from the solar arrays toward us (this explains the long exposure time and bad image quality compared with the approach observations done on 11/12 and 12/13 November).

This movie was recorded between 04:51 and 05:20 UTC on 14 Nov. It consists of 10 images with an exposure time of  2 min and a separation of 3 min. The field is located in Leo and has a size of 5 x 5 arcmin; North is up and East is left. The telescope was tracking the stars so that Rosetta appears as a stripe while the stars appear as dots. Rosetta moves roughly from East to West. The bright star at the bottom of the image has magnitude 12.5, and the bright star at the top has magnitude 13.4.

This image was taken at 05:39 UTC on 14 Nov with an exposure time of 5 min. The field is located in Leo and has a size of 5 x 5 arcmin, North is up and East is left. The telescope was tracking the stars so that Rosetta appears as a stripe a little above centre-right of the image. The spacecraft moves less than 1 arcmin during the 5 min exposure, roughly from East to West. The brightest star at the bottom of the image has magnitude 12.6. Note that the vertical bright line that crosses Rosetta is a camera artefact. Kristin Wirth wrote:

"I will leave the Teide Observatory and Tenerife now, and head for the airport. I really enjoyed my time at the Optical Ground Station, together with a great team and at a special location - opposite the Teide mountain, with the clouds below us. I would like to thank everybody for their support, in particular Lilian Dominguez Palmero who operated the telescope for me." -- Kristin

And we're going to take this opportunity to thank Kristin for all her great help and input for the Rosetta Blog over the past week!

Finally, a 'farewell' (for now) from us both and a sincere 'thank you' to every one who visited the Rosetta Blog - it has been a lot of fun and we have especially enjoyed seeing the many comments left by visitors. 

We plan to be back again in 2010 as Rosetta continues on her fascinating journey to the outer Solar System - including preparations for deep-space hibernation and the encounter with asteroid Lutetia on 10 July 2010 (from a distance of just 3000 km!). --Amruta & Daniel

New images from the OSIRIS team received over the weekend! 

  

Click to download the hi-res version

False-colour composite of cloud structures in an anticyclone over the South Pacific. It depicts a portion of the scene below with five times the resolution. The image was taken with the narrow-angle camera on 13 November at 06:48 CET, using orange, green and blue optical filters

 

Click to download the hi-res version

Taken three minutes before the image above with the wide-angle camera, this image is shown in a logarithmic scale to bring out details in the varying light intensity. As a result the scene looks roughly the same as it would appear to the human eye.

Click to download the hi-res version

The same area in the South Pacific imaged with the orange filter of the narrow-angle camera in a logarithmic intensity scale.

--Amruta

As a reader commented, the images clearly show Earth smiling back at Rosetta!

The OSIRIS team has composed this animation from a sequence of images taken once every 24 hours, beginning when Rosetta was at a distance of 50 000 km at 22:28 UTC last night. The resolution is 6.5 km/pixel. Access the animation in the main ESA web site. -- Amruta