What Will The ExoMars Lander Do?
The importance of today's landing
Today on Mars, a 13-year-old American robot will look up from its crater to photograph the arrival of a new European companion. It’s a solar system first: No robot on the the surface of another planet has ever been there to greet a new space traveler. The newest arrival, named Schiaparelli, will be doing its part to ensure that someday, humans will be the ones watching and waving as ships come and go.
The European Space Agency’s Schiaparelli lander is touching down today in Meridiani Planum, the same area where the Opportunity rover has been trundling along since 2003. Opportunity is about 10 miles outside of Schiaparelli’s landing area, and will try to photograph the parachute as the European robot plummets Marsward. (The Curiosity rover is half a world away.)
Schiaparelli promises yet another white-knuckle descent and landing on Mars, and the stakes are high: Half of all Mars missions have blown up, skipped past the planet, or crashed. To date, NASA is the only space agency to successfully land and operate anything there. Europe tried in 2003, too, but its Beagle 2 lander never made contact after arriving on the surface.
Schiaparelli is part of a European-Russian effort called ExoMars, which was continually reshaped and reimagined as nations in the European Union wrangled with recession and cutbacks. Ultimately, Italian scientists and engineers, working with partners in several other countries, designed a small set of instruments that can bring home new science. Schiaparelli will look for lightning on Mars and is the first spacecraft to study the planet’s electric fields, using a meteorology instrument suite called DREAMS.
Safe on Mars
True to spaceflight tradition, the team found a way to make an acronym out of a word that meant something to them. It stands for Dust Characterisation, Risk Assessment, and Environment Analyser on the Martian Surface.
“Most of the people that worked on this project also worked on previous ExoMars missions that changed so many times,” Francesca Esposito, DREAMS’ chief scientist, said in an interview. “There have been several years of working on instruments that for one reason or another have never flown, so this is our dream, to finally go to Mars.”
Schiaparelli is arriving during peak dust storm season on Mars, which is typically a bad time to be a Mars robot. Even worse — or better, depending on who you ask — Mars could see a rare global dust storm this year. But the lander is designed to study the dust, especially the electric fields that are thought to help churn it into the atmosphere and cause dust devils and giant dust storms. European Space Agency scientists expect clear skies for the arrival, however.
“In the last few days, it seems the sky is clearer, but I hope something will change and we will see more dust,” Esposito says.
DREAMS is studying Martian weather, but its most important mission is analyzing electrical fields on Mars for the first time. Mars is thought to have a global electrical circuit connecting its surface to the ionosphere. The wee planet’s atmospheric pressure is less than one percent of Earth’s, so wind can’t be the only thing to lift up Martian dust. On Earth, you need about 10 mph wind to lift sand grains. On Mars, you’d need a 60 mph gale. So a global static charge might be one of the mechanisms that kicks up dust and forms dust devils and dust storms.
Understanding this is important for human missions for a few reasons, Esposito says. Dust storms can blind rovers and snow over human habitats. And the electrical fields might interfere with radio communications, or, even worse, discharge — meaning lightning.
“During dust storms, dust devils and dust events, we could see some electrical discharge, but we don’t know,” Esposito says. “What is known is that nothing is known.”
DREAMS also has some basic but important meteorological instruments, including an anemometer to measure wind speed and direction.
The lander is named for Giovanni Schiaparelli, the Italian astronomer who thought he saw networks of lines — canali — on Mars in 1877. Over the weekend, it separated from the Trace Gas Orbiter, a new Mars observer that will monitor the planet’s atmosphere and serve as an important relay for a European-Russian rover planned for arrival in 2020. The TGO will look for methane and other atmospheric gases found in very small concentrations, but which could have major implications for biological or geological activity.
ESA’s real goal was to deliver the orbiter, but the agency tacked on a landing demonstrator, which itself is really just designed to prove that the European version of a sky crane can work. For that reason, Schiaparelli has a limited battery supply, and DREAMS is only planned to work for two sols, or Martian days (a sol is 24 hours and 39 minutes long).
ExoMars Trace Gas Orbiter and Schiaparelli Separation
“We’re hoping to be able to do more, but it depends on the conditions on Mars. Our battery is affected by temperature, and it cannot work at temperatures below -17 C,” says Esposito. “When the temperature goes down, we need to switch on the heaters, and the heaters will use the energy of the battery, so less energy is then available for science. So in our worst case, considering the cold temperatures, we can survive two sols.”
It’s spring in the southern hemisphere, but nights on Mars are still unspeakably cold, so the team expects DREAMS to survive no more than eight sols, Esposito says.
For ESA, even one day is a major achievement, however. The tally of successful Mars landings is currently 7 for the US, and zero for Europe. Russia landed the Mars 3 probe in 1971, but it failed after 20 seconds. Beagle 2 landed on Christmas Day 2003 but never phoned home, and a NASA orbiter found it just last year. Delivering Schiaparelli safely is the main goal; testing Mars’ winds is just a bonus.
“The idea was to acquire the technology to land a payload on Mars, so it was not designed to be there to make measurements for a long time. It was not a scientific tool,” says Esposito. “But considering that there was a little space there, ESA launched a call to accommodate a small experiment. So we applied, and now we have DREAMS. Even if we have a short lifetime, the measurements that we can perform are very noble.”
Measuring Martian lightning, atmospherics and dust devils to pave the way for human colonists? That seems like a noble goal indeed.