Timeline: Mars Express makes closest-ever flyby of Phobos

Find below an outline timeline for the flyby of Phobos around 29 December 2013.

Initial tracking will be provided by DSA 1, ESA's 35m deep-space ground station at New Norcia, Australia. Then NASA will provide support with two of their 70m stations, DSS-63 near Madrid, Spain, and then DSS-14 in Goldstone, California. Finally, Mars Express will be tracked again by New Norcia.


ESA's 35m New Norcia station in action

Phobos flyby timeline

13-362T 17:40:00Z New Norcia (NNO) station starts tracking Mars Express
13-363T 01:30:00Z DSS-63 acquires the signal from MEX
13-363T 03:21:52Z DSS-63 takes over as primary station
13-363T 03:44:05Z NNO stops tracking MEX
13-363T 07:09:00Z Mars Express – closest approach to Phobos (45km from surface)
13-363T 07:20:35Z Signals from closest approach reach Earth (due to the one-way light time)
13-363T 08:55:00Z DSS-14 begins tracking MEX
13-363T 11:02:50Z DSS-14 takes over as primary station
13-363T 11:25:00Z DSS-63 stops tracking MEX
13-363T 17:06:02Z NNO begins tracking MEX
13-363T 18:37:53Z NNO takes over as primary station
13-363T 19:00:00Z DSS-14 stops tracking MEX
13-364T 01:12:30Z The transmitters on MEX start switching off; flyby 'mission' ends

This timeline was taken directly from the operations plan used by the MEX flight team at ESOC; the '13-262' and '13-263' annotation simply refers to the year and day of the year. So, 362 is 28 December, 363 is 29 December and so on. 'Z' time (Zulu-time) refers to GMT time; CET time is +1 hour. All times subject to change.

Tracking stations

The station coverage must be uninterrupted (except during occultation by Mars) for the entire 35-hour period of the flyby mission. Therefore, an overlap in coverage between stations has been intentionally planned so as to be able to detect and eliminate any inaccuracies due to the stations themselves.

"This overlap imposes a very specific handover procedure between the ESA Estrack and NASA DSN networks; this handover has been rehearsed numerous times with the actual ground stations," says Michel Denis, the MEX Operations Manager at ESOC.

The sequence of station hand-over – from ESA to NASA to ESA – makes this a truly international, intercontinental, inter-agency endeavour!

Michel also points out that the use of NASA's 70m stations is critical to the accuracy of the measurements. "We'd like to thank our US colleagues for the provision of some very specific station passes; this is due to the very cooperative efforts of the DSN station scheduling team."

NASA 70m tracking station. Credit: NASA

NASA 70m tracking station. Credit: NASA

Should any of the station listed above become unavailable at the last minute, a backup has been booked in advance using ESA's 35m Estrack stations, which could take over to 'save' the Phobos flyby; this would incur a penalty in reduced measurement accuracy.

First Contact! Mars Express’ first ‘conversation’ with Curiosity

As we reported yesterday, Mars Express had a busy Sunday evening, pointing first at NASA's Curiosity rover on the surface of Mars and then swinging around to do another relay pass with Opportunity. We received the data from both of these passes this morning over ESA's New Norcia ground station and, on first look, it seems that both relays were very successful.

First Laser-Zapped Rock on Mars

First Laser-Zapped Rock on Mars. This composite image, with magnified insets, depicts the first laser test by the Chemistry and Camera, or ChemCam, instrument aboard NASA's Curiosity Mars rover. The composite incorporates a Navigation Camera image taken prior to the test, with insets taken by the camera in ChemCam. The circular insert highlights the rock before the laser test. The square inset is further magnified and processed to show the difference between images taken before and after the laser interrogation of the rock. The test took place on Aug. 19, 2012. Credit: NASA/JPL-Caltech/LANL/CNES/IRAP

In ESA's MEX team, we're particularly excited to have had our first contact with Curiosity – proof that the amazing new rover from the United States can talk with our veteran European Mars orbiter!

At the start of the contact, Mars Express was over 3600 km from Curiosity's landing site in Gale Crater and closed in to only 1300 km by the end of the contact – streaking across the sky as seen from Curiosity.

During this overflight by Mars Express, it 'hailed' Curiosity in Gale Crater and the rover responded. The two spacecraft then autonomously established a link with each other and Curiosity flowed data back to Mars Express for nearly 15 minutes. This international chat between two spacecraft in deep space is proof of all our preparation, standardisation and cooperation work in action – so it's something both agencies can be proud of.

ESA's first 35-metre deep-space ground station is situated at New Norcia, 140 kilometres north of Perth in Australia. The 630 tonne antenna will be used to track Rosetta and Mars Express, the latter to be launched in 2003, as well as other missions in deep space. The ground station was officially opened on 5 March 2003 by the Premier of Western Australia, Hon Dr Geoff Gallop. Credits: ESA

ESA's first 35-metre deep-space ground station is situated at New Norcia, 140 kilometres north of Perth in Australia. The 630 tonne antenna will be used to track Rosetta and Mars Express, the latter to be launched in 2003, as well as other missions in deep space. The ground station was officially opened on 5 March 2003 by the Premier of Western Australia, Hon Dr Geoff Gallop.
Credits: ESA

The actual data that flowed back was made available to NASA earlier today, who will now retrieve and process the data.

Hopefully we'll have some info from them in the next couple of days about what exactly was contained within. We'll also receive (within Tuesday) the 'housekeeping' telemetry of Melacom – information on how our radio performed. This will allow us to double-check the performance of this first important contact with Curiosity.

The data was sent at a rate of only 8 kbps – 125 times slower than the 1-Mbit/second Internet connection you might have at home!

We wanted to take things easy to start with, though, and test the performance of the link. Nonetheless, we received 955 data packets from Curiosity, totalling 867 kilobytes of data.

This will be the first of several contacts with Curiosity in the future, as we better learn how to use and optimise this relay link between the two craft and the two space agencies. Watch this space for more details as we get them on this pass and the future contacts between Mars Express and Curiosity.

 

NASA MSL mission communicates with ESA station

Status

This just in from Wolfgang Hell, one of our ESTRACK engineers looking after the ESA station support to MSL. ESA's 35m New Norcia (NNO) station made contact with MSL earlier this afternoon -- and the connection went fine! Wolfgang wrote:

We had a fully nominal MSL pass over NNO and NASA JPL reports that the telemetry obtained via the first communication chain at NNO was error free. I expect reports for data receipt from chains 2 and 3 during the upcoming telecon.

 

ESA, NASA, Parkes: Big ears on Earth will listen to MSL descend

Editor's note: We're delighted to post this update on the international, behind-the-scenes cooperation to implement the MSL 'ground listening' campaign. It highlights the hard work, months of preparation and terrific cooperation between ESA, NASA and international partners on a technical, operational and interpersonal level. Thanks to NASA's Susan Kurtik and ESA's Wolfgang Hell for kindly providing information for this report.

On 6 August, ground stations and a radio telescope operated by multiple nations will be listening to signals from NASA's MSL mission as it descends through the Martian atmosphere to deliver the Curiosity rover safely onto the Red Planet's surface.

ESA's first 35-metre deep-space ground station is situated at New Norcia, 140 kilometres north of Perth in Australia. The 630 tonne antenna will be used to track Rosetta and Mars Express, the latter to be launched in 2003, as well as other missions in deep space. The ground station was officially opened on 5 March 2003 by the Premier of Western Australia, Hon Dr Geoff Gallop.  Credits: ESA

ESA's first 35-metre deep-space ground station is situated at New Norcia, 140 kilometres north of Perth in Australia.
Credits: ESA

The stations involved are all in the Land Down Under, since that's the bit of Earth that will be facing Mars at around 01:00 CEST next Monday morning, as MSL approaches its nail-biting plunge into the Mars atmosphere to touch down in Gale Crater.

During this crucial phase of the mission, MSL will transmit two radio links – one direct to Earth in X-band, which is also being used  for routine telecommanding during the cruise to Mars, and a ‘proximity link’ in the UHF band for direct communication with spacecraft orbiting Mars.

To get a good idea of the importance of the ground campaign, let's first look at the in-flight tracking efforts for the proximity link.

International fleet tracks MSL from Mars orbit

"The primary monitoring of MSL's Entry, Descent and Landing – EDL – phase will be provided by two NASA spacecraft in orbit around Mars: Mars Reconnaissance Orbiter [MRO] and Mars Odyssey. These two 'platforms' will be backed up by ESA's Mars Express [MEX]," says Michel Denis, MEX Spacecraft Operations Manager and responsible for MEX tracking support to MSL at ESOC.

(See our earlier post, 'Mars Express to track 7 minutes of terror' for details – Ed.)

Odyssey is the only one of the three that can provide the so-called 'bent-pipe' (or real-time) relaying of signals and is expected to give the first indication to NASA that Curiosity has arrived; confirmation of safe landing is expected by NASA at around 07:31 CEST.

Odyssey over Mars' South Pole: NASA's Mars Odyssey spacecraft passes above Mars' south pole in this artist's concept illustration. The spacecraft has been orbiting Mars since October 24, 2001. Credit: NASA

Odyssey over Mars' South Pole: NASA's Mars Odyssey spacecraft passes above Mars' south pole in this artist's concept illustration. The spacecraft has been orbiting Mars since October 24, 2001. Credit: NASA

In contrast, MRO and MEX can only track, store and then forward recorded signals later.

Artist's concept of the Mars Reconnaissance Orbiter. Image credit: NASA/JPL

Artist's concept of the Mars Reconnaissance Orbiter. Image credit: NASA/JPL

"Only Odyssey can receive, decode and then relay to Earth the actual telemetry data coded into the those signals. Conversely, MRO and MEX will save on board 'open-loop' recordings," says Denis.

This means they will record only the spectra of the radio signals and the related Doppler variations in signal intensity, and not the encoded telemetry.

(NASA's Susan Kurtik, MSL Mission Interface Manager at JPL, adds: In fact, we will be able to extract telemetry from the MRO open-loop recording, although it will take ~8 hours to process - Ed.)

(The variations in signal strength due to the Doppler effect are explained by the rather famous ambulance siren analogy.)

Ground tracking campaign provides crucial support

Now, let's look at the ground tracking campaign, the crucial, 'behind-the-scenes' activity in support of Curiosity's arrival at Mars provided by stations on Earth.

Continue reading

New Norcia to track Mars Science Laboratory

On 6 August, ESA's 35m deep space station at New Norcia, Australia, will track the arrival of NASA's Mars Science Laboratory at the Red Planet.

On 31 July, in a test, New Norcia successfully acquired telemetry from MSL at 13:30 CEST; all data was passed to NASA JPL. Two additional test tracking sessions are booked for 2 and 3 August.(We'll post an update on NNO's involvement in MSL arrival later in the week.)

ESA's 35m station at New Norcia, Australia, will track NASA's MSL arrival at Mars. Credit: ESA

ESA's 35m station at New Norcia, Australia, will track NASA's MSL arrival at Mars. Credit: ESA

More details on NNO via ESA web.

And, if you haven't seen this yet, surf on over to NASA's JPL website to access a very cool visualisation tool that demos the entire EDL (entry, descent and landing) phase - note: Java required.