Testing cooperation: ESA’s Mars Express transmits commands to NASA rover

This update sent in earlier today by ESA’s Simon Wood, one of the engineers working on the Mars Express mission operations team at ESOC.

Today, ESA’s Mars Express orbiter will send telecommands to NASA’s Curiosity rover on the surface of Mars.

This self-portrait of NASA's Curiosity Mars rover shows the vehicle at the "Mojave" site, where its drill collected the mission's second taste of Mount Sharp. Credit: NASA/JPL-Caltech/MSSS

This self-portrait of NASA’s Curiosity Mars rover shows the vehicle at the “Mojave” site, where its drill collected the mission’s second taste of Mount Sharp. The scene combines dozens of images taken during January 2015 by the Mars Hand Lens Imager (MAHLI) camera at the end of the rover’s robotic arm. The pale “Pahrump Hills” outcrop surrounds the rover, and the upper portion of Mount Sharp is visible on the horizon. Darker ground at upper right and lower left holds ripples of wind-blown sand and dust. Full image and caption via NASA web. Credit: NASA/JPL-Caltech/MSSS

The transmission is part of a routine quarterly test of the communications link between MEX and Curiosity – NASA’s Mars Science Laboratory (MSL). Aside from its prime science mission, Mars Express is able to provide contingency communications with MSL (or with any NASA rovers) in case of any problems with the normal data relay links.

This particular test consists of MEX hailing MSL – sending a specific signal requesting MSL to listen – then transmitting commands (provided by the MSL team at NASA/JPL) to the rover and then recording data transmitted back.

Background sequence of activities

  • MEX mission planning system schedules pointing of MEX’s UHF (ultra high-frequency) antenna at MSL – end-December 2104
  • MSL team provides command file (i.e. the telecommands to be transmitted) to the MEX flight control team at ESOC – last week of February 2015
  • MEX flight control team uploads the commanding ‘products’ (files to be executed on board MEX) on 27 February; these were generated on 24 February
Mars Express orbiting the Red Planet - artist's impression Credit: ESA/Alex Lutkus

Mars Express orbiting the Red Planet – artist’s impression Credit: ESA/Alex Lutkus

Operations timeline today

All times UTC

14:29 MEX will slew from Earth pointing to pointing its UHF antenna at MSL on the surface
14:41 MEX UHF antenna switches on – takes 15 mins to warm up
14:56 Overflight begins with MEX hailing MSL; overflight lasts 9 mins
15:05 MEX begins to slew back toward Earth pointing

Data received from MSL will be transmitted back to Earth by MEX at around 16:30 UTC via ESA’s deep-space ESTRACK station in Malargüe, Argentina.

Later, NASA’s deep-space network teams will extract the data from the MEX packet archive and pass this on the the MSL team for analysis.

Best regards from the MEX control team at ESOC!

– Simon

One plan becomes two plans

Editor’s note: Those who have been following our blog will know that the MEX Flight Control Team at ESOC have been actively preparing for the flyby of comet C/2013 A1/Siding Spring on 19 October. Initial estimates gave the possibility that Mars Express might have to contend with a large particle flux – and that several (2? 3?) very high-speed (~56 km/sec!) particles might bash into the spacecraft. Happily, additional observations by ground and space telescopes (including the ESA/NASA Hubble Space Telescope) have allowed initial estimates to be refined and the risk is now understood to be much lower – and perhaps even as low as zero. In today’s blog post, the team explain how this (happy!) real-life, real-time development is affecting their preparations for fly-by.

Comet C/2013 A1 Siding Spring seen on 6 September 2014 from Argentina. Image credit: César Nicolás Fornari https://www.facebook.com/cesar.fornari

Comet C/2013 A1 Siding Spring seen on 6 September 2014 from Argentina. Image credit: César Nicolás Fornari https://www.facebook.com/cesar.fornari

Late last year, estimates given in scientific papers estimated that over the duration of the encounter, the number of large cometary particles per square metre would be around 1. As MEX’s area in the most protected attitude is about 3m2, we could then expect about 3 potentially significant impacts. Not good!

By the middle of this summer, published estimates (based on new images and additional modelling) were indicating a flux of around 10-6 particles per m2, which, for Mars Express, very roughly equates to a 1-in-300,000 chance of being hit. It’s starting to look like our comet C/2013 A1/Siding Spring will manifest itself as a more friendly passer-by than initially thought and that it won’t be hurling clouds of large particles at unthinkable speeds towards Mars and its man-made satellites.

Closest approach: If Mars were Earth. Credit: NASA/JPL

Closest approach: If Mars were Earth. Credit: NASA/JPL

So why the big change?

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