December 17, 2008

Goodnight, Mars

At mission’s end, scientist Sam Kounaves looks back at the Phoenix Mars Lander and the insights it provided

By Marjorie Howard

During the long, cold Martian nights of October and early November, the Phoenix Mars Lander’s computer began losing its memory. It would shut down and sleep during the night and reboot itself each morning, resetting itself to the day before it left Earth on August 4, 2007.

Click the play button to watch a video about the Phoenix Mars Mission.


“It did what it was supposed to do,” says Sam Kounaves, a professor of chemistry who was a co-investigator on the $325 million Phoenix mission. “It would try to transmit and receive signals, give up and go to sleep. It was a heroic saga with this spacecraft sitting on Mars, being on its own and trying to follow commands and communicate with home, and slowly losing power.”

The final communication from the Phoenix was a brief signal received on November 2, when, as expected, lessening sunshine left the solar-powered Phoenix without enough energy to keep its batteries charged. According to NASA, the Lander operated two months longer than its planned three-month mission. It landed on the Martian arctic plain on May 25, 2008.

For Kounaves, losing contact with the spacecraft has been a wistful experience following the success of the NASA mission, which sought to learn if Mars had ever been habitable. As a co-investigator, he and his research team helped design a wet chemistry lab and the experiments that tested Martian soil on board the ship.  

The discoveries, he says, have been nothing short of astonishing. The Phoenix detected water—in the form of ice—and confirmed it in tests on the ship. Soil, also tested on board, was found to contain magnesium, potassium, sodium and chloride—minerals essential for organisms to survive.

“This has basically been a scientific triumph in terms of understanding the surface and climate of Mars,” says chemist Sam Kounaves. Photo: Melody Ko

“More astoundingly,” Kounaves says, “were three major findings that change how we view Mars: the pH was moderately alkaline; we found perchlorate, which was totally unexpected; and we found high concentrations of calcium carbonate.”

The alkaline pH is similar to many soils on Earth, says Kounaves, meaning it would be friendly for a variety of plants and microbes, given the right atmosphere and temperatures and containing nothing else toxic.  “It was not super acidic, like bleach, as some had predicted.”

Perchlorate, a salt, meanwhile, could be an energy source for micro-organisms while calcium carbonate, or calcite, controls the pH of sea water on Earth.

Nothing was found in the soil to rule out the idea that there could have been some form of life on Mars at one time, Kounaves says. “This has basically been a scientific triumph in terms of understanding the surface and climate of Mars.”

Kounaves, who has been involved in projects aimed at exploring Mars for the last dozen years, says one of the important implications at Tufts is the opportunity for graduate and undergraduate students to continue to analyze data sent back by the spacecraft. “There were 25 sensors aboard, and there is a lot of information to analyze,” he says. “We can’t do experiments anymore, but we can run experiments in the lab to help us understand more about the chemistry of the soil.”

As the Phoenix began to die, Kounaves felt the poignancy of the situation. “Even though it was a robot, we had put so much effort and time into it that it was personified,” he says. “Every day we sent it commands to run the experiments, and a day later it would send us the results. It encompassed all our hopes and dreams and brought to life all the work that went into it from the moment it was first thought of a dozen years ago.”

The Martian year is twice as long as a year on Earth, and the planet will begin to warm up next September. “Maybe the Phoenix could wake up, but we don’t think so,” says Kounaves. “It will be covered with dry ice and was not made to survive minus 120 degrees Celsius. But you never know.”

See earlier coverage of Sam Kounaves’ Mars work:

Marjorie Howard can be reached at

Article Tools

emailE-mail printPrint