The European Space Agency’s (ESA) Schiaparelli Mars lander is being readied for its plunge onto the Red Planet.

Controllers at ESA’s mission control in Darmstadt, Germany have uploaded commands that will govern the lander’s descent and touchdown on Mars.

Meanwhile, discussions are underway regarding the best seat in the house for viewing Schiaparelli’s landing – by NASA’s Opportunity Mars rover.

Two-parter

ESA’s ExoMars 2016 mission is a two-parter: The Trace Gas Orbiter has been carrying Schiaparelli since launch on March 14 of this year.

Upon arrival at Mars on October 19 — and its parent craft brakes into an elliptical orbit around Mars — Schiaparelli will test the technology needed for Europe’s ExoMars 2020 rover to land.

Taking the fall

One of the most crucial moments will be Schiaparelli’s landing, set for 14:48:11 GMT (16:48:11 CEST) on October 19.

During landing, the recently sent upload of commands include ejecting the front and back aeroshells, operating the descent sensors, deploying the braking parachute and activating three groups of hydrazine thrusters to control the lander’s touchdown speed.

Radar love

Radar will measure Schiaparelli’s height above the surface starting at about 4 miles (7 kilometers) altitude.

Above Mars, Schiaparelli will briefly hover before cutting its thrusters, leaving it to fall freely.

The targeted touchdown site is a region in Meridiani Planum – a location that is near NASA’s Opportunity rover that is already on-duty.

Ringside seat?

How solid of a chance is it for the NASA Opportunity rover spotting the Schiaparelli sky show?

“It is exciting to think about the possibility of seeing a visitor coming,” said Mark Lemmon on the Opportunity tactical shift rover control group. He is associate professor in the Department of Atmospheric Sciences at Texas A & M University in College Station, Texas.

Lemmon told Inside Outer Space that there is a realistic possibility, but not a likelihood, of seeing part of Schiaparelli’s parachute descent – maybe one chance in seven.

Constrained downlink

“The parachute would be, at best, around pixel-sized. If there is enough residual glow in the heat shield, that could be a second pixel,” Lemmon said. “We are balancing the desire to maximize the odds of getting at least a few images of Schiaparelli with the constrained downlink we have available that sol [Martian day].”

“If we were talking about a flat plain, and without dusty season, we’d be trying to prune down our options,” Lemmon said. That is, image the entry phase, turn to image the parachute phase, maybe use multiple directions since the lander ellipse is so big – from west on a bit past north, in angle, he said.

Robot’s point of view

But the Opportunity rover is in a hole. The Schiaparelli entry is not viewable, Lemmon said. If the European probe lands in the middle of the landing ellipse, or comes in short, nothing will be viewable. If the probe goes long, to the east, it might come over the crater rim from the rover’s point of view, and also be closer to the rover.

“We are watching the horizon,” Lemmon said. “Previously, we figured about one chance in seven of having the parachute go through the frame. We’d likely point to maximize the chance of seeing anything, but there may be arguments for one part of the descent over another.”

Great bonus

Lemmon added that any sharp-shooting of an incoming Schiaparelli has to cope with the martian dust, as the sky is comparable in brightness to the parachute.

“Because of that, we think we have to use [Opportunity’s] Pancam’s higher sensitivity to small objects and its filters, rather than Navcam’s larger field of view,” Lemmon said. “We’re still collecting information about the descent expectations, weather, and local horizon, and will use all of that for our final plans on October 17 when we uplink to the rover.”

Lemmon said that the ESA Schiaparelli team has been very interested in the images. Those images would be an “extra perspective” on Schiaparelli’s position, winds, maybe heat shield deployment.

“The images are not central to what they need,” Lemmon said, “but if we get them it would be a great bonus. We have a shot at watching an incoming spacecraft from the surface of another planet…good times!”

Surface science

Once safely on the surface, the timeline will operate Schiaparelli’s science instruments for a planned two days – and possibly longer.

Sitting on Mars, a small meteorological station (DREAMS) will operate for a few days.

DREAMS is onboard to measure local weather conditions at the landing site, such as temperature, humidity, pressure, dust opacity, wind speed, and wind direction. It will also perform measurements of the electrical properties of the Martian atmosphere, the first time this has ever been done.

The Mars orbiter was built by Thales Alenia Space – France, and the builder of the Schiaparelli lander is Thales Alenia Space – Italy.

For a new video showing the Schiaparelli landing sequence, go to:

http://m.esa.int/ESA_Multimedia/Videos/2016/10/Schiaparelli_s_descent_to_Mars