Do you use Twitter? Are you as intrigued by comets as we are? Then tell us 'Why comets are cool' and you might win a trip to ESA's operations centre in Germany on 15 June to celebrate 25 years of comet exploration.
On 15 June, ESA will mark a quarter-century of comet science and say (temporarily) 'good night' to Rosetta with a special event at ESOC in Darmstadt, Germany. One talented Twitter user will be selected to join us as our guest at the event.
Between now and 9 June, you're invited to tell us, via Twitter, why comets are cool.
To take part, simply tweet your entry. It must include the "#coolcomet" hashtag, leaving you a mere 130 characters, so brevity is important.
Your tweet may also include a single URL, or weblink, that links to a 'non-text' submission, such as a picture, image, photo, animation, video, audio file or any other sort of digital content. Maybe you can sing a song about comets, and submit a link to a video of you singing in YouTube? (The judges will look unfavourably on any content that takes longer than 3 minutes to view).
We'll review all submissions and our expert judging panel will grade tweets for clarity, wit, humour, scientific accuracy and originality (and, yes, spelling counts).
Editor's note: A very quick update before we head off to Toulouse to cover ATV docking - all's well that end's well with Rosetta's longer-than-expected manouevre campaign. SOM Andrea Accomazzo confirmed this morning that the final manourvre was indeed completed on 17 February
I met on 10 February with Rosetta Spacecraft Operations Manager Andrea Accomazzo here at ESOC to catch up on all that's happened with Rosetta since our last update on 18 January.
Click to listen (or download) a full, 8:00-min recording of his explanation below, but to summarize, here is what has been happening:
Rosetta experienced a safe mode - an automatic reset of the spacecraft - that happened during the thruster burn late in the evening of 18 January
The safe mode stopped the thruster burn and placed the spacecraft into a basic, safe, Earth-pointing mode, waiting commands
The teams here at ESOC spent the next few days determining the cause - which seemed to relate to how the thrusters function when in continuous operation
In part by using a number of advanced tools and techniques developed here by the Advanced Mission Concepts and Technologies Office, the Rosetta team were able to isolate the problem
The flight control team worked with flight dynamics experts to devise a new mode of operation for the thrusters - basically commanding them to switch rapidly on and off instead of running continuously as before
The new thruster mode was extensively tested and simulated using software and the Rosetta engineering model, which is kept here at ESOC for just such purposes.
A new set of manoeuvres were planned and uploaded, and during the last week of January, the spacecraft successfully re-started the manoeuvre campaign
It has now completed almost 98% of the required change in velocity and is more or less lined up to meet Comet 67P/Churyumov-Gerasimenko in 2014
The final manoeuvre of this new campaign will be conducted today, starting at 19:38 CET and running for about 43 minutes
Andrea and the rest of the team here at ESOC are just delighted! An initial problem that caused real concern and could have become critical has been investigated, analysed and a fix found - which enables the spacecraft to perform even better than before.
We'll update you again when we have news on the start of Rosetta's long hibernation, scheduled now for the June 2011 timeframe. -- Daniel
Please accept our sincere apologies for being so long in updating the blog!
A number of events conspired to enforce a lag in reporting the results of the manoeuvre activities in January. First, an unexpected 'safe mode' occurred - in which the spacecraft experienced a problem and basically reset itself, waiting for fresh commands - on 18 January during one of the planned long-duration burns.
Next, the flight control team were very involved in resetting Rosetta, figuring out what caused the safe mode and implementing a fix - which they did. :-)
This took time, during which we didn't post while we waited for news on the success of the fix. Further, in the middle of January, your hard-working Rosetta blog editorial team got a bit occupied with ESA's new ATV Johannes Kepler blog.
To make up for all the delay, we're planning a very nice update next week and will speak with Spacecraft Operations Manager Andrea Accomazzo at ESOC to get the full details on the past fortnight of activities. -- Daniel
Rosetta's next orbital correction manoeuvre (OCM) is taking place tonight. The thruster burn began at 17:59 CET (spacecraft time) and will run until shortly after midnight (371 mins total). The planned change in speed is 274 m/s with respect to the Sun. Like last night, the Rosetta teams at ESOC will be on shift until late!
Some bits of info collected from around ESOC earlier today on the Rosetta burn last night:
First - An update from the Rosetta flight control team: yesterday's burn went according to plan! The team noted a very slight over performance - meaning that the thrusters provided more of a boost than planned but still well within the expected range (more on that below). For the flight control & flight dynamics teams, the last shift ended at 04:30 CET this morning (just after the burn ended).
Next - the detailed burn schedule is posted below (click on the 'Full story' link), sent in by Roberto Porta, one of the Rosetta Spacecraft Operations Engineers at ESOC. Note that we'll wait to do any further blog updates until we get the final results after the last slot, now booked for 23 January.
Finally - we received a note from Trevor Morley, the team lead for flight dynamics support for Rosetta. Trevor wrote:
Preliminary assessment of last night's manoeuvre based on Doppler data indicates that the velocity change was about 1 m/s more than the planned 300 m/s. Such an error is well within the expected performance accuracy and the accumulation of such errors over the first four legs of the manoeuvre will be compensated for by an eventual re-optimisation of the 5th and final leg (an 'orbit trim'). This re-optimisation will be based upon an accurate reconstruction of the orbit for which purpose both ESA and NASA delta-DOR measurements will be made in addition to routine Doppler and range measurements.
'Delta-DOR' refers to the ultra-accurate position determination technique used by both ESA and NASA. Delta-DOR uses two widely separated antennas to simultaneously track a transmitting probe in order to measure the time difference ('delay time') between signals arriving at the two stations. The technique of measuring this delay is named Differential One-way Range (DOR). More details via the ESTRACK pages in the ESA web site. -- Daniel
Some nice photos just sent in from ESA/ESOC where the flight dynamics team and the flight control team are watching closely this evening as Rosetta conducts an important thruster burn to help line up the spacecraft for her rendezvous with a comet in 2014. Scroll down for details!
Rosetta Spacecraft Operations Engineer Roberto Porta
on console in the Rosetta dedicated control room
Members of the flight dynamics team on shift to monitor tonight's manouevres
And here's what Rosetta Spacecraft Operations Manager Andrea Accomazzo is seeing on his screen: a display based on telemetry received from Rosetta showing the jump in thruster temperature as the burn got underway about an hour ago at 20:03 CET.
A quick update from ESA/ESOC: one of the most important trajectory correction manoeuvres (TCM) as Rosetta line-ups for her encounter with Comet 67P/Churyumov-Gerasimenko in 2014 is now taking place.
Tonight's burn, which began at 19:03 UTC (20:03 CET) spacecraft event time (meaning the time at Rosetta, which is now over 629 mn km from earth), is expected to produce a 'delta-v' - or change in velocity with respect to the Sun - of 300 m/second. The burn is part of a series in the coming days that should produce an overall change of 778 m/second - one of the longest-running burns conducted to date by any of the Agency's deep-space missions.
This series of burns are crucial in that they are necessary to help Rosetta line up for her final approach to 67P/Churyumov-Gerasimenko.
ESA's first deep-space ground station at New Norcia (Western Australia) - now communicating with Rosetta.
Rosetta Spacecraft Operations Manager Andrea Accomazzo and members of the flight control team are watching progress closely from the Rosetta Dedicated Control Room at ESOC; he sent in a mail a few minutes ago to report that they are monitoring evolution of propellant pressure and making sure that everything is working as expected on board the spacecraft.
Signals from Rosetta are being received on Earth via ESA's giant 35m deep-space tracking station at New Norcia, Australia.
We'll check with the team tomorrow and provide more details here in the blog. -- Daniel
What does a scientist do to visualise a space journey? Build a model, of course. A model of Europe’s Rosetta comet-chaser made out of LEGO® blocks started out in this small way and has grown into a high-fidelity Rosetta Lander Education Kit.
A really nice way to end our Lutetia fly-by coverage! Stuart Atkinson, one of our regular blog visitors, runs his own excellent science & astronomy outreach efforts in the UK (visit his site: Cumbrian Skies). Stuart's sent in a poem this morning in celebration of Rosetta's fabulous results of yesterday. Thanks Stuart! -- Daniel
For all these years you were merely
A smear of light through our telescopes
On the clearest, coldest night; a hint
Of a glint, just a few pixels wide
On even your most perfectly-framed portraits.
But now, now we see you!
Swimming out of the dark - a great
Stone shark, your star-tanned skin pitted
And pocked, scarred after aeons of drifting
Silently through the endless ocean of space.
Here on Earth our faces lit up as we saw
You clearly for the first time; eyes wide
With wonder we traced the strangely familiar
Grooves raked across your sides,
Wondering if Rosetta had doubled back to Mars
And raced past Phobos by mistake –
Then you were gone, falling back into the black,
Not to be seen by human eyes again for a thousand
Blue Moons or more. But we know you now,
We know you; you’ll never be just a speck of light again.
(C) ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA
At a distance of 36 000 km, the OSIRIS Narrow Angle Camera (NAC) took this image catching the planet Saturn in the background.
Approach images of Asteroid Lutetia. The first image was taken at 06:18 (about 9.5 hours before closest approach, 510000 kms from the asteroid), the last one at 14:15 (about 1.5 hours before closest approach, 81000 km from the asteroid.). The resolution changes from 9.6 km/px to 1.5 km/px.
Final sequence of images before closest approach (CA-8, CA-4:40, CA-2, CA-1:50)
Zoom into detail with grooves and craters.
Zoom in on a possible landslide and boulders at the highest resolution.
Lutetia was discovered in 1852 from the Paris balcony of French painter turned astronomer Hermann Goldschmidt. To honour his home city, he called it 'Lutetia', after the Roman name for Paris. It was an early vindication of Goldschmidt's career change.
He became interested in astronomy after attending a talk by the great French astronomer Urbain Le Verrier, of the Paris Observatory. The previous year, Le Verrier had correctly predicted the position of the then unknown planet Neptune, sparking its discovery. The mathematical success made him famous. His Paris lectures were timed to coincide with an easily visible lunar eclipse in 1847. He clearly inspired Goldschmidt.
Captivated by the possibilities for discovery, the painter bought a telescope, appropriately enough with the proceeds from the sale of two portraits of Galileo. He set it up on his sixth floor apartment's balcony and began to sweep the skies.
Lutetia was his first discovery, made on the evening of 15 November 1852, but not his last. During the next nine years, he discovered 13 more asteroids making him the most successful asteroid hunter of his generation.
He was awarded the Gold Medal of the Royal Astronomical Society in 1861, and has a crater on the Moon named after him. - Stuart