After five months digging up and analyzing soil samples on Mars, verifying the existence of ice and noting that snow falls from Martian skies, NASA's Phoenix Mars Lander has gone silent.
The robotic machine has effectively frozen to death in the increasingly long, cold Martian winter nights, NASA reported late yesterday. NASA engineers received the last signal from the Lander on Nov. 2, though scientists will continue listening for another few weeks in case the craft comes back to life and messages home.
"Phoenix not only met the tremendous challenge of landing safely, it accomplished scientific investigations on 149 of its 152 Martian days as a result of dedicated work by a talented team," said Phoenix Project Manager Barry Goldstein.
Since the Lander is powered by solar cells and the Mars nights grow longer and longer this time of year, at the end of October scientists began to remotely power down as many parts of the Lander as possible to minimize its energy needs. That allowed a few instruments to keep running as long as possible. And once the Mars Lander dies, it's doubtful it could ever be brought back to life after spending months in the dark and frigid cold.
Scott Hubbard, who worked at NASA for 20 years and today is a professor in the department of aeronautics and astronautics at Stanford University, said the Lander had been in a "Lazarus" mode before it went silent on Nov. 2.
"Every night it died and if enough it got enough sun the next day, it would rise from the dead," said Hubbard, who helped plan the Mars mission. "When it died, its memory was wiped every night. It was like a baby with no programming. They were nursing it along but nobody believed it would last much longer."
In a press conference yesterday afternoon, NASA engineers noted that while the spacecraft's work has ended, the job of analyzing the data it sent back to Earth has just begun. "Phoenix has given us some surprises, and I'm confident we will be pulling more gems from this trove of data for years to come," said Phoenix principal investigator Peter Smith of the University of Arizona in Tucson.
Mission manager Chris Lewicki had said in a previous interview that the close of the Lander's mission is proving to be a tough time for the Mars Lander team. They're grieving for the machine that has sent more information back to Earth about the Red Planet than any other spacecraft in any previous mission.
The Lander, for instance, found ice just under the surface of the soil, proving that water -- a key element to support life -- exists there. Scooping up soil with its robotic arm the Mars Lander has also taken and sent back microscopic images of Martian soil.
The Lander has discovered that snow falls from clouds about 2.5 miles from the surface of Mars and then evaporates before it reaches the ground.
And between soil tests done in the Lander's wet chemistry set and its eight ovens, evidence has been sent back that shows that Martian soil is much like Earth's. The Martian dirt is very alkaline, with a pH level of between 8 and 9. The Lander also found magnesium, sodium, potassium and chloride in the dirt.
Next year, NASA is slated to launch an SUV-size rover on a trip to Mars. With an estimated budget of $2 billion, the Mars Science Laboratory will carry three different kinds of cameras, as well as chemistry instruments, environmental sensors and radiation monitors. According to NASA, all of those instruments are designed to help scientists continue to figure out whether life ever existed on Mars and to prepare to send humans to the Red Planet.
In 2004, President George W. Bush called on NASA to send humans back to the moon by 2020 in preparation for a manned-mission to Mars some day.