UI scientists seek to answer the ‘big question’

IOWA CITY - Among NASA's top priorities in its exploration of the universe is to determine whether life exists beyond our planet. And, right now, that question is focused around Earth's red-hued neighbor.

The federal space agency right now has six missions at Mars, including two involving University of Iowa scientists.

NASA's most recent arrival to our solar system's fourth planet from the sun is the Mars Atmosphere and Volatile Evolution spacecraft, referred to as MAVEN.

The spacecraft has nine instruments observing the Martian upper atmosphere, ionosphere and solar-wind interactions, and UI physics professor Jasper Halekas is lead investigator on MAVEN's 'solar wind ion analyzer.”

That instrument aims to track solar wind interactions with Mars's upper atmosphere by, among other things, measuring the density, temperature and velocity of the solar wind.

The goal of the mission is to understand how the Martian climate has changed over time from what appears to be an 'earlier warmer and wetter” environment to the 'cold, dry planet” it is today.

'There was a time when Mars had a thick atmosphere and water standing on the surface,” Halekas said. 'But there is no water left today.”

Hypotheses of the planet's evolution include water moving into the Martian rocks or escaping into space.

'Our mission is about testing the latter hypothesis,” Halekas said.

Collaboration

MAVEN is getting some help in that endeavor from NASA's Mars Express mission, which UI professor Don Gurnett helped launch more than a decade ago. Express began its journey to Mars in June 2003 and arrived in December of that year with the goal of searching for subsurface water from orbit and deploying a lander onto the Martian surface.

Its instruments were designed to observe the planet's geology and composition, along with hits atmosphere. Contrary to the MAVEN project, Mars Express has been looking for the presence of water below the planet's surface - possibly in the form of rivers, pools, aquifers or permafrost.

And Gurnett said his mission has found it in the form of 'a lot of ice.” The Express instruments have confirmed a polar ice cap on Mars and discovered permafrost in the ground.

'But, at one point in the past, the atmosphere was much more dense,” Gurnett said, noting that a dense atmosphere would have meant warmer temperatures. 'So why did the atmosphere disappear?”

One theory is that gas from the sun - or solar wind - changed the makeup of the Martian ionosphere, which is where the MAVEN mission comes in. With two missions orbiting the planet, the instruments can collaborate to track the inputs and outputs of particles as solar winds pass.

'We can't be in two places at one time,” Halekas said. 'So this helps us.”

‘Returning good science'

The MAVEN mission launched one year ago, and it spent several months in a 'commissioning” phase. The spacecraft completed those activities last week and formally has started its one-year primary science mission.

The mission has fuel to last 10 years, and Halekas said 'as long as we are returning good science,” he expects the mission to continue.

MAVEN is off to a good start after helping to observe and measure the impact of Comet Siding Spring, a rare Oort cloud comet that last month passed closer to Mars than any previously known flyby. Both MAVEN and Express collected data from the October event, which surprised NASA researchers by coming within 87,000 miles of Mars at its closest approach.

The result was an unprecedented meteor shower that slammed into the Martian atmosphere, changing its chemistry.

If the Mars missions are able to determine more about why the Martian atmosphere changed, Halekas said, scientists could gain a better understanding of planetary evolution.

'It could have some interesting implications,” he said. 'It's another data point to see what could have happened if Earth took a little different path and how fragile it is.”

Gurnett said the missions also could get to the bottom of one of NASA's primary endeavors - to find living things elsewhere in the universe.

'That is the big question,” he said.