What is ESA's ExoMars Rove

ESA: ExoMars is doing a lap

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The complete ExoMars 2022 mission, consisting of the carrier module, the descent module, the Kazachok surface platform and the Rosalind Franklin rover, carried out important "spin tests" in preparation for the trip to Mars. The science operation of the rover was tried and a new parachute strategy developed. Information from the European Space Agency (ESA).

ExoMars descent module without carrier module during the balancing test.
(Image: Thales Alenia Space)
March 17, 2021 - The complete ExoMars 2022 mission, consisting of the carrier module, the descent module, the Kazachok surface platform and the Rosalind Franklin rover, has carried out important "spin tests" in preparation for the trip to Mars. Rosalind Franklin's rover twin on Earth has conducted scientific testing activities for the first time, including drilling samples and close-up photography. A new parachute strategy was chosen prior to the next series of high altitude drop tests.

balancing act
An essential preparation for the mission's flight to Mars and immersion in the planet's atmosphere is to make sure the spacecraft is perfectly balanced as it turns.

The ExoMars 2022 mission consists of four main units: the Rosalind Franklin Rover, led by ESA and the Roscosmos-led Kazachok surface platform, both of which will conduct scientific activities on the Martian surface, as well as the descent module in which they are encapsulated and the carrier module, that will transport them to Mars after takeoff.

During the journey to Mars, the complete "spaceship network" (consisting of all four units) will rotate at around 2.75 rotations per minute in order to stabilize itself on its trajectory. The dynamic balancing test checks that there are no imbalances that could cause wobbling in space and that would require too much fuel to compensate. It is also important that the spacecraft is balanced so that it rotates smoothly around its axis of rotation and that its antenna remains pointed at the earth for a communication link to be possible.

As soon as the descent module is released near Mars, about 30 minutes before entering the atmosphere, the original rate of rotation is maintained until the atmospheric effects kick in and the first parachute is deployed. Complete coasting takes place as soon as the propulsion system of the landing platform starts near the surface of Mars.

Therefore, two dynamic balancing tests were carried out: one test for the complete composite spacecraft and one without the carrier module, only for the descent module with the rover and platform inside. Actual flight modules were used in all tests conducted at Thales Alenia Space's clean room facilities in Cannes, France.

During the test with the spacecraft assembly, it was subjected to a rotation of up to 30 rpm, which corresponds to a centrifugal acceleration of 2g at the outer edge of the heat shield of the descent module. After the environmental tests in Cannes are completed, the spacecraft will return to Thales Alenia Space's facilities in Turin, Italy in mid-March for further functional tests.

Control of the ExoMars cameras.
(Image: TAS / ESA / ExoMars / PanCam team)
Rehearsals for Rover Science
Meanwhile, the Rosalind Franklin "ground test model" at the Rover Operations Control Center (ROCC) in Turin has reached an exciting milestone. While the replica rover is still stationary in the clean room, the operations team steered it as if the rover were on the surface of Mars.

"It's really exciting to have used the ROCC's command sequence for the first time, as we will during the real mission," said Luc Joudrier, ExoMars Rover Operations Manager at ESA. "We defined the rover's 'activity plan', sent it to the rover, and then recorded and processed the data. It's great to see the ROCC doing this."

One of the activities was to test Rosalind Franklin's special drill. It is the first time in Mars research that a rover is able to take soil samples from a depth of up to 2 m, where ancient biomarkers could still be protected from the intense radiation on the surface, and bring them to the on-board laboratory. In the latest simulation, the simulated rover was instructed to use its drill with a dummy sample on board and transport it to the drawer of the analytical laboratory. In reality, on Mars, a sophisticated laboratory will then analyze the composition of the sample.

ExoMars Rover model - test operation in knowledge mode.
(Image: Thales Alenia Space)
In addition, the rover imaged the sample with its close-up imager, a camera located on the underside of the drilling unit.

The high-resolution panorama cameras were also activated as part of an image calibration.

The twin rover will shortly enter the ROCC's Mars terrain simulator to carry out mobility commands and other functional tests. The rover control team and scientists will rehearse these simulations many times, focusing on various rover activities as part of their training between now and the arrival of the mission on Mars.

New strategy for parachute tests
The two main parachutes, which should help bring the mission safely to the surface of Mars, are slated for the next high-altitude parachute test in Kiruna, Sweden, in May / June this year. After the drop test from a great height in November 2020, which resulted in some local damage to both parachutes, a new path was taken.

"We have revised our strategy to have the best possible chance of qualifying the ExoMars parachutes this year so that we can meet our launch window in 2022," says Thierry Blancquaert, ExoMars deputy program team leader. "We have therefore invited a second experienced parachute manufacturer to contribute to the ExoMars program by providing us with additional parachutes that we can use in the coming opportunities."

In addition to the Arescosmo parachutes, newly manufactured parachutes are now being manufactured by Airborne Systems, which helped bring NASA's Perseverance rover safely to Mars earlier this month. Airborne Systems also supports the ground based parachute extraction tests being conducted at NASA / JPL.

In contrast to the landing of the NASA rover Perseverance on Mars with only one parachute and the so-called sky crane, two main parachutes are required for the ExoMars mission by ESA-Roscosmos - each with its own pilot parachute for the extraction - to connect the descent module to the Braking descent through the atmosphere.

The full deployment sequence was qualified in the first altitude drop test in 2019, in which a test vehicle was dropped from a stratospheric balloon from an altitude of 29 km. However, significant damage to the parachute canopies was observed in the same test. This led to a new design of the parachute bag and a revised packing strategy, along with reinforcements on both parachute canopies. The modified bags and parachutes were successfully tested in the first ground-based dynamic high-speed extraction tests at NASA / JPL facilities in December 2019. The original damage was also successfully replicated in a series of dedicated soil-based tests late last year, which confirmed the causes of the anomalies observed. The damage to the parachutes observed during the November 2020 drop test was significantly less severe than that observed during the 2019 test, and the review of the test data indicated the early opening process for subsequent improvements. "The new parachute canopies are stronger and more robust, and the redesigned bags have already shown promising results, so we look forward to completing the logistics for the next high-altitude parachute test in Kiruna, Sweden, in the May to June timeframe, "says Thierry Blancquaert.

In addition to a new bag design, a revised approach to folding addresses the problem of parachute lines twisting during casting, which previously limited the parachute's ability to inflate correctly. Another high-altitude drop test in Oregon, USA, is expected in September through November to maximize testing opportunities. If necessary, an additional opportunity could be used in Oregon in February / March 2022.

In the months leading up to the high altitude drop tests, slots are scheduled with the ground based dynamic extraction test facility to check performance if changes are made to the parachutes, folds, or pockets prior to flight.

Drop tests from high altitudes require complex logistics and severe weather conditions, making them difficult to plan, while the ground tests can be repeated in no time. This frees up significantly more time in the test campaign and reduces the risk by allowing more tests to be carried out in a short time frame. "We have learned valuable lessons from the current parachute qualification race when it comes to developing such complex missions, particularly the need for more robust testing of new technologies much earlier in the mission timeline," said Francois Spoto, head of Mars Exploration Group the ESA. "Together with our large industrial consortium and international partners, we are continuing to work on overcoming the last hurdles to get Europe safely to Mars."

ExoMars timeline.
(Image: ESA)
The ExoMars mission will launch aboard a Proton-M rocket with a Breeze-M upper stage in the launch window September 20 - October 1, 2022 from Baikonur, Kazakhstan. After landing safely in the Oxia Planum region on Mars on June 10, 2023, the rover will set off from the surface platform and look for geologically interesting locations to drill below the surface and determine whether life has ever existed on our neighboring planet. The ExoMars program, a joint project of ESA and Roscosmos, also includes the Trace Gas Orbiter (TGO), which has been orbiting Mars since 2016. In addition to its own scientific mission, the Trace Gas Orbiter will provide vital data relay services for the mission on the surface; he already supports NASA's surface missions, including landing the Mars 2020 Perseverance Rover last month.

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