[UPDATED] Mars Express chats with Curiosity: Practice makes perfect

UPDATE 16 June: MEX Deputy Spacecraft Operations Manager James Godfrey just emailed to report that yesterday's MSL overflight seems to have gone rather well! "We have received good telemetry from the MEX Melacom radio and we are now in the process of analysing the data to extract the signal from MSL."


Today, Mars Express established a communication link with NASA's Curiosity rover (MSL) on the surface of Mars to conduct an important test prior to the arrival of ESA's ExoMars Trace Gas Orbiter (TGO), carrying the the ExoMars Entry, Descent and Landing Demonstrator Module (EDM), Schiaparelli, in October.

Curiosity selfie Credit: NASA/JPL-Caltech/MSSS

Curiosity selfie Credit: NASA/JPL-Caltech/MSSS

The test saw Curiosity serve as a stand-in (rove-in?) for Schiaparelli on the surface, transmitting a signal to MEX similar to how Schiaparelli will transmit during landing on 19 October. From orbit above, MEX had its lander communication system (Melacom) – with recently updated software – configured as it will be in October, and the orbiter tested receiving signals from below.

Here's the timeline of how today's test went, as programmed; all commands were uploaded in advance and the sequence was executed automatically on board (times in UTC).

  1. 2016-06-15 06:22:53.000 - MEX begins to slew to point the radio antenna towards MSL's position on the surface
  2. 2016-06-15 06:40:00.000 - Melacom Switches on
  3. 2016-06-15 06:55:00.000 - MSL starts transmitting its beacon
  4. 2016-06-15 06:55:00.000 - After a 15-minute warm-up, Melacom starts recording the signal from MSL
  5. 2016-06-15 07:05:00.000 - Melacom is powered down and the first part of the recording is complete
  6. 2016-06-15 07:10:00.000 - After a 15-minute wait, Melacom is powered back up
  7. 2016-06-15 07:14:00.000 - No waiting this time; 4 minutes allowed for start up as Melacom starts its second recording
  8. 2016-06-15 07:23:00.000 - MSL stops transmitting
  9. 2016-06-15 07:23:00.000 - Melacom is powered down and the second recording is complete
  10. 2016-06-15 07:23:10.000 - Test complete; MEX now begins to slew back to Earth; data will be dumped in a few hours
Melacom

A photo of the Melacom UHF communications package carried on Mars Express.

Note: Data were still arriving as we posted this, so no analysis to report yet:

Here's a brief description of the actual Schiaparelli arrival activity that this test was meant to exercise (see also: A little help from friends):

On 19 October, about 80 minutes before landing, expected at 14:48 GMT (16:48 CEST), Schiaparelli will wake up and a few minutes later begin transmitting a beacon signal (Schiaparelli will have se4parated from the ExoMars/TGO orbiter on 16 October).

Mars Express will already have pointed Melacom’s small antenna to the spot above the planet where Schiaparelli will appear, and will begin recording the beacon signal, ‘slewing’ – rotating – continuously so as to keep its antenna pointed to follow the module’s descent trajectory.

ExoMars 2016 Schiaparelli descent sequence Credit: ESA/ATG medialab

ExoMars 2016 Schiaparelli descent sequence Credit: ESA/ATG medialab

“Recording will continue through touch-down and the first approximately fifteen minutes of surface operation, after which Schiaparelli will be programmed to switch off and Mars Express will stop recording,” says Mars Express Spacecraft Operations Engineer Simon Wood.

The Schiaparelli signal data will be saved on board Mars Express in two segments; the first, larger, segment will record signals from wake up of the module until about 20 minutes before it reaches the Martian atmosphere, while the second, smaller, segment will record the descent through the atmosphere, touch down and the first 15 minutes of surface operations.

“Then, Mars Express will re-orient its main antenna toward Earth and download the second, smaller segment of recorded data, which should contain the first in-situ confirmation from Mars of Schiaparelli’s arrival and landing,” says Simon.

The data will be received via ESA’s Cebreros deep-space ground station, in Spain, by the Mars Express flight control team at ESOC, ESA’s mission control centre in Darmstadt, Germany, and then passed on to the ExoMars mission controllers.

Even more friends

Mars Express won’t be the only ‘set of ears’ listening in to Schiaparelli’s descent that day.

At Mars, NASA’s Mars Reconnaissance Orbiter (MRO) will monitor signals from Schiaparelli, but only after its landing, due to MRO’s orbital geometry.

MRO - Mars Reconnaissance Orbiter

Credit: NASA/JPL-Caltech

The TGO orbiter, while conducting its own critical orbit entry manoeuvre, will also record Schiaparelli’s descent and landing, but this data can only be downloaded some hours after it has completed orbit entry.

In the following days, Mars Express and MRO – as well as the other NASA Mars orbiters, Odyssey and MAVEN – will each serve as data-relay platforms, overflying Schiaparelli’s landing site in Meridiani Planum once or twice per day, picking up data transmitted from the lander during its nominal two- to four-day surface science mission, and relaying these to Earth.

Mars Express will also support the Schiaparelli mission through remote sensing measurements over the landing site during several weeks prior to the event.

 

Mars rover gets instructions daily from NASA via a network of antennae

Nice article today in WaPo:

Brian van der Brug/AP - Activity lead Bobak Ferdowsi

Brian van der Brug/AP - Activity lead Bobak Ferdowsi, who cuts his hair differently for each mission, works inside the Spaceflight Operations Facility for NASA's Mars Science Laboratory Curiosity rover at Jet Propulsion Laboratory (JPL) in Pasadena, Calif. on Sunday, Aug. 5, 2012.

To get its messages to Earth, Curiosity first sends information to a pair of orbiters, Odyssey and Reconnaissance, that were sent in 2001 and 2005, respectively, to analyze Mars from a distance and are constantly circling the planet. (The Mars Express orbiter, operated by the European Space Agency, is also available if necessary.) The antennae on the orbiters are more than 1,300 times as powerful as the antenna on Curiosity. The rover waits for the orbiters to pass overhead to ship its messages, usually around 3 p.m. and again at 3 a.m.

Access full text via Washington Post

 

Mars Express rocking and rolling with NASA’s Curiosity & Opportunity

On 19 August, Sunday evening (European time), Mars Express will start its first data relay with NASA's Mars Curiosity rover in style by fitting in not just our first pass with Curiosity but also by 'rolling away' afterwards to talk with NASA's veteran Mars rover, Opportunity.

Still Life with Rover This full-resolution self-portrait shows the deck of NASA's Curiosity rover from the rover's Navigation camera. The back of the rover can be seen at the top left of the image, and two of the rover's right side wheels can be seen on the left. The undulating rim of Gale Crater forms the lighter color strip in the background. Bits of gravel, about 0.4 inches (1 centimeter) in size, are visible on the deck of the rover. Credit: NASA

Still Life with Rover This full-resolution self-portrait shows the deck of NASA's Curiosity rover from the rover's Navigation camera. The back of the rover can be seen at the top left of the image, and two of the rover's right side wheels can be seen on the left. The undulating rim of Gale Crater forms the lighter color strip in the background. Bits of gravel, about 0.4 inches (1 centimeter) in size, are visible on the deck of the rover. Credit: NASA

This will be the first time in the history of the Mars Express mission where this double lander contact has been attempted within a single orbit of the spacecraft (1 orbit around Mars for Mars Express lasts around 7 hours).

As the spacecraft approaches the planet it will turn away from Earth and 'roll' over the top of Curiosity's new home in Gale Crater, keeping the Melacom antennas pointed directly at the new rover.

After this contact, Mars Express will turn back to Earth briefly and then spin away again, performing the same 'Spot Pointing' manoeuvre for Opportunity as Mars Express flies over its location in Endeavour Crater. This double relay will be an exciting test of the capabilities of Mars Express, both in relay terms and in pointing, and to not only prove our communication capability with the new (and fantastic!) Curiosity rover but also to continue our commitment to its predecessor – the venerable Opportunity rover.

A Digital Opportunity Rover on Mars Credit: Mars Exploration Rover Mission, Cornell, JPL, NASA Rover Model: D. Maas - Synthetic Image: Z. Gorjian, K. Kuramura, M. Stetson, E. De Jong.

A Digital Opportunity Rover on Mars Credit: Mars Exploration Rover Mission, Cornell, JPL, NASA Rover Model: D. Maas - Synthetic Image: Z. Gorjian, K. Kuramura, M. Stetson, E. De Jong. Via http://apod.nasa.gov/apod/ap051214.html

The past weeks have seen intense cooperation between NASA and ESA to coordinate and plan these activities, which are intended as demonstrations of the relay capabilities of Mars Express. The overflight of Opportunity will be part of a long-standing activity to periodically check the ability of Mars Express to relay data from Opportunity, if ever needed.

Many of these overflights were done leading up to the landing of Curiosity to cement the technical ability of the two agencies to work together on planning routine relay operations. The overflight of Curiosity will be the first time that Mars Express and Curiosity have actually 'talked' to each other.

During the landing of Curiosity, Mars Express only listened in and recording the radio signal of Curiosity, but Sunday evening, 19 August, the two spacecraft will actually have a 'conversation' and for the first time Mars Express will receive and decode actual data from the lander.

We're confident in the ability of the two spacecraft to be able to communicate for several reasons – the main one being that both implement an international standard called Proximity-1 [this is mentioned in our earlier Melacom post - Ed].

This standard was designed to make sure that even though the spacecraft come from different manufacturers and different agencies, the way they talk to each other is still the same – it can be thought of like an 'agreed common language'.

On top of this, is our extensive experience relaying data for Phoenix, Spirit and Opportunity and the fact that a team from QinetiQ (who built our Melacom radio) travelled to JPL to test a copy of it with a copy of the Curiosity radio. However, any new activity in space is challenging and we stand ready at ESOC to investigate, analyse and improve – optimising our ability to support the Curiosity mission for NASA.

All of this will allow Mars Express to make a call to Curiosity in Gale Crater and between the spacecraft agree autonomously to exchange data. Curiosity will send back data that will be decoded by Mars Express and stored ready for forwarding to Earth; then we'll quickly reset and prepare a very similar activity for Opportunity in Endeavour Crater.

Next, on Monday morning, Mars Express will send the data to ESA's 35m New Norcia (Australia) ground station and then from there it will make its way to ESOC and on to the control room at JPL.

The data's journey will be long (Gale Crater/Endeavour Crater -> Mars Express -> New Norcia, Australia -> ESOC, Germany -> JPL, USA) but we'll make sure it arrives safe and sound – proving the ability of Mars Express to support communications with both Curiosity and Opportunity whenever needed.

We'll post more details when we know the results of the test and can hopefully announce on Monday that Mars Express has been 'qualified' as a really-long-distance relay for Curiosity – expanding the network of spacecraft and cooperation at Mars in spectacular style!