Leonard David's INSIDE OUTER SPACE

Credit: ESA

Landing Update: 

“We appear to have five images between earliest parachute deployment time and latest backshell jettison time, and do not see anything that looks like Schiaparelli,” 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.

“We were advised that it [Schiaparelli] was more likely coming in short than long,” Lemmon told Inside Outer Space.

Landing day

On October 19th, the European Space Agency’s (ESA) ExoMars 2016 entry, descent and landing demonstrator module is set to burrow through the Martian atmosphere and land in a relatively flat area in Meridiani Planum, close to the equator in the southern hemisphere.

Within possible viewing range of ESA’s Schiaparelli’s landing site is NASA’s Opportunity rover, on Mars duty since its landing in 2004.

Credit: ESA

Locked and uploaded

In the hope of catching a glimpse of the overhead action, Opportunity is locked and uploaded with special instructions.

Word is that Opportunity operators will try to image Schiaparelli’s entry, descent and landing (EDL) with the rover’s Pancam.

“It is likely that the descent with the parachute will be obscured from Opportunity’s viewpoint by Endeavour’s rim because the landing site is to the west of the rover’s current location,” explains Ray Arvidson, Mars Exploration Rover deputy principal investigator at Washington University St. Louis.

“If the descent extends more to the east of the targeted location we may see the parachute,” Arvidson told Inside Outer Space. “Thus we are sequencing Pancam images of the possible descent path,” he said.

Approximate region in box where Schiaparelli lander may be visible above horizon by Opportunity if vehicle goes long.
Credit: James Rice/MER/JPL

Mid-afternoon on Mars

Schiaparelli was released by its mothership – ESA’s Trace Gas Orbiter – on October 16^th.  Atmospheric entry of the lander is expected 14:42 GMT / 16:42 CEST, landing 14:48 GMT / 16:48 CEST).

Schiaparelli’s EDL would occur in mid-afternoon of Opportunity’s Sol 4528.

Any rover imagery of the incoming ESA vehicle would arrive on Earth late Wednesday afternoon, Arvidson said, “but it is unlikely we will be able to image the parachute, given the targeted landing site.”

Remote chance

Meanwhile, Opportunity has been busily exploring Endeavour Crater in its 10th extended mission, explains astrogeologist Jim Rice, part of the geology theme group for the Mars Exploration Rover project and senior scientist at the Planetary Science Institute in Tucson, Arizona.

Opportunity rover’s current location at Spirit Mound. Will it catch the Schiaparelli sky show?
Courtesy: James Rice/MER/JPL

“We will attempt to image Schiaparelli as it arrives in our neck of the woods on October 19th,” Rice told Inside Outer Space. “But if the entry and descent of Schiaparelli is nominal, the Opportunity rover will not see anything because its path will be blocked by the topography of the western rim of Endeavour crater,” he said.

“However, there is a remote chance we could see it above the crater rim if the descent trajectory is long toward the east,” Rice added. “Bottom line is that we will be giving it our best effort and, hopefully, we get lucky.”

Opportunity odds

So what are the odds of Opportunity 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.

ESA’s Schiaparelli landing at Meridiani Planum on Mars on October 19, 2016.
Credit: ESA/ATG medialab

Pixel-sized chute

“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.

Rim shot

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.”

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.

Artist’s impression of Schiaparelli, the ExoMars entry, descent and landing demonstrator module, as it approaches the Martian surface.
Credit: ESA/ATG medialab

Extra perspective

“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.”

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.

Artist impression of the Schiaparelli module on the surface of Mars.
Credit: ESA

“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!”