Update from Spacecraft Operations Manager Michel Denis at ESOC:
Comet Siding Spring has flown by Mars .
Thanks to the DSN radio-science receiver at Madrid (then Goldstone) we could follow the Mars Express S-Band beacon practically all the time, including closest approach and comet plane crossing. Despite the very low level of concern, this was quite good to have.
After flyby, acquisition of signal occurred as planned at 22:25CEST, which implicitly confirmed that the spacecraft is operating normally. First systematic checks of spacecraft telemetry were performed for all sub-systems and showed fully nominal behaviour. There are no unexpected events or out-of-limits.
The downlink of the science data has started. The observation programme focused on the atmosphere/ionosphere continues for another two days. The HRSC pictures from the encounter are due for downlnk on Thursday.
After a year of intense preparation for technical readiness, our warm thanks to all teams who have supported the flight control team at ESOC, ESAC, ESTEC, NASA/DSN and beyond. We still have a mission.
Image of comet C/2013 A1 (Siding Spring) at 4.8 arcminutes from Mars, as seen on 2014 October 19 at 20:20 UT via ESA's Optical Ground Station, equipped with a 1-meter telescope, on Tenerife, Canary Islands. North is to the left of the frame. The comet was imaged under poor sky conditions, while it was 17° above the southwestern horizon. High humidity and strong winds also affected the image quality, giving a "fuzzy" appearance to the nearby stars.
Comet C/2013 A1 seen from ESA's Optical Ground Station, Teide Observatory, Tenerife, on 19 Oct 2014 at 20:19:46UT (22:19:46CEST). Credit: ESA/M. Micheli/D. Abreu
For anyone who didn't find the comet in the full frame image above, here's a cropped version with the comet marked!
Mars is, of course, much brighter than Siding Spring - here, it's marked in red. Credit: ESA/M. Micheli/D. Abreu
You'll have read in past blog posts that Mars Express will be (has already started) sending a beacon signal to Earth to enable the mission operations team to monitor the craft. It it continues being received, all is (most likely!) well. If it disappears, this could indicate a problem.
Mars Express orbiting the Red Planet - artist's impression Credit: ESA/Alex Lutkus
The beacon was switched ON at 14:48CEST (ground receive time) and is set to run through to the 'all clear' at about 21:30CEST tonight. But there was a loss of signal at 15:27CEST – and this was expected. Spacecraft Operations Engineer Andy Johnstone at ESOC explains why:
The blocked signal is caused by the spacecraft itself!
The Large Gain Antenna (LGA) will be hidden by the spacecraft body or the solar arrays at various periods during the transmission of the beacon today [as the craft moves through various pointings], causing a loss of reception on ground.
We do have a second LGA on top of the spacecraft that could have also been used (between them they are visible from any angle) but we elected not to move the antenna selection switches during the flyby. It is something we only do rarely and decided that, as we are conducting (important!) nominal science during the flyby, we would accept the three blackout periods. It also gives us an opportunity to map the true limits transmit of the LGA – we are always keen to sneak in additional tests and learn more about our spacecraft wherever possible!
Editor's note: Beacon blackouts will run
- 15:27-16:15 CEST
- 17:33-18:32 CEST
- 21:53-23:09 CEST
Excellent view by an astronomer in the UK, imaging the comet and Mars via the iTelescope.net virtual telescope at Siding Spring. In the image, both Siding Spring and Mars can be seen this morning at about 11:30CEST. Great work, M. Mobberley!
An excellent view of Mars and Comet Siding Spring comprising several separate images captured by Scott Ferguson, Florida, USA, this morning around 01:00 UTC (03:00CEST). More images and links to live feeds via the CIOC Siding Spring Facebook group.
Mars and Siding Spring seen on the day of their closest approach, 19 October 2014, by Scott Ferguson, Florida, USA. Image & live feeds via https://www.facebook.com/groups/cioc.sidingspring/
An excellent image showing both #MarsComet C/2013 A1 Siding Spring and the Red Planet in the same view, as they are now close enough together as seen from Earth. The beauty of this image belies the technical challenge of imaging both a faint comet and the (relatively) bright planet. Well done, James!
Comet Siding Spring and Mars seen one day prior to the comet's closest approach on 19 Oct 2014 at 18:27UTC. Image acquired from iTelescope Siding Spring, Australia. Credit: James Willinghan
A fabulous artist's impression showing, approximately, the relative sizes of The City of Angels, 67P/C-G and Siding Spring! Well done and very inspiring... Image credit: Credit: ESA, anosmicovni
On 31 March 2013, not long after it was discovered, astronomers observed Comet Siding Spring with Herschel. This was just one month before the observatory exhausted its supply of liquid helium coolant and ceased to collect data. When Herschel observed it, the comet was about 6.5 AU from the Sun. The observations were performed following a proposal for Director’s Discretionary Time from Peter Mattisson from the Stockholm Amateur Astronomers (STAR) in Sweden.
These three images show emission from the dust in the coma surrounding the nucleus of Comet C/2013 A1 – also known as Comet Siding Spring – as observed at three different far-infrared wavelengths with ESA's Herschel space observatory. Credit: SA/Herschel/PACS/Cs. Kiss et al. 2014
The commands that will automatically pace Mars Express through its pointings and science observations on Sunday are now confirmed on board, so we are 'GO' for Siding Spring flyby.