posted May 26, 2008 11:33 AM            

PASADENA, Calif. - NASA's Phoenix Mars Lander survived a risky plunge through the Red Planet's atmosphere and touched down in Mars' northern polar region on Sunday, sending back pictures of a bleak-looking, oddly patterned plain.

Over the next 90 days, the probe is due to dig into the permafrost to look for evidence of the building blocks of life.

Cheers swept through Mission Control at NASA’s Jet Propulsion Laboratory when the touchdown signal from the Phoenix Mars Lander was detected after a nail-biting descent. "Phoenix has landed! Phoenix has landed! Welcome to the northern plains of Mars," deputy systems engineer Richard Kornfeld announced.

The first data from the probe indicated that it was sitting almost exactly level on its landing site in Mars' Vastitas Borealis region.

“In my dreams it couldn’t have gone as perfectly as it went,” NASA project manager Barry Goldstein said. “It went right down the middle.”

Among Phoenix’s first tasks were to check its power supply and the health of its science instruments, and unfurl its solar panels after the dust settled. Then the first pictures were taken and transmitted to Earth. The pictures showed the fully deployed solar panels, the soil under one of Phoenix's landing pads and long-range looks toward the horizon of the northern plains.

The plains appeared to broken up by polygon-shaped fractures — as expected, based on orbital imagery. Scientists say such patterns arise in the polar regions of Earth as well as Mars, due to wind action or repeated cycles of freezing and thawing.

"Underneath this surface, I guarantee, is ice," said Peter Smith, the Phoenix mission's principal investigator from the University of Arizona at Tucson.

Dan McCleese, a chief scientist at JPL, said the polygonal terrain was "absolutely beautiful."

"It looks like a good place to start digging," he said.

Seven minutes of terror

Phoenix plunged into the Martian atmosphere at more than 12,000 mph (19,200 kilometers per hour) after a 10-month, 422 million-mile (675 million-kilometer) voyage through space. It performed a choreographed dance that included unfurling its parachute, shedding its heat shield and backshell, and firing thrusters to slow to a 5 mph (8 kph) touchdown.

The automated descent was dubbed "the seven minutes of terror" for good reason. More than half of all nations’ attempts to land on Mars have ended in failures.

Smith said the room was thick with tension during those seven minutes. "I couldn't let go of the chair," he said. "I had a grip on it."

Sunday's touchdown was the first successful soft landing on Mars since the twin Viking landers touched down in 1976. NASA’s twin rovers, which successfully landed on Mars four years ago, used a combination of parachutes and cushioned air bags to bounce to the surface.

Phoenix’s landing was a relief for NASA, since Mars has a reputation for swallowing spacecraft. More than half of all nations’ attempts to land on Mars have failed.

NASA Administrator Mike Griffin marveled at the precision of the Phoenix team members' aim, saying they achieved better than "one part in 10 million of accuracy." Ed Weiler, NASA's associate administrator for the science missions directorate, said that was the equivalent of hitting a golf ball in Washington — to make a hole-in-one on a golf course in Australia.

"And you have to remember, that hole is moving," JPL Director Charles Elachi quipped.

posted June 27, 2008 12:20 AM            

Stick an asparagus plant in a pot full of Martian soil, and the asparagus might grow happily, scientists announced Thursday.

An experiment on the Phoenix Mars lander showed the dirt on the planet’s northern arctic plains to be alkaline, though not strongly alkaline, and full of the mineral nutrients that a plant would need.

“We basically have found what appears to be the requirements, the nutrients, to support life whether past, present or future,” said Samuel P. Kounaves of Tufts University, who is leading the chemical analysis, during a telephone news conference on Thursday. “The sort of soil you have there is the type of soil you’d probably have in your backyard.”

Mars today is cold and dry, and the surface is bombarded by ultraviolet radiation, making life unlikely, but conditions could have made the planet more habitable in the past. Plants that like alkaline soil — like asparagus — might readily grow in the Martian soil, provided that other components of an Earth-like environment including air and water were also present.

The preliminary findings from Phoenix do not answer whether life ever existed on Mars (or might still exist somewhere underground), only that conditions, at least at this location, are not the harshest imaginable. The soil, taken close to the surface, was similar to what is found in parts of Antarctica, Dr. Kounaves said. The soil elsewhere on the planet could well be very different; even the soil farther down in the ground could turn out to be acidic or otherwise vary in composition.

The Phoenix is capable of performing the same chemical analysis on three more samples.

In a different experiment, a tiny oven heated another sample of the Martian soil to 1,800 degrees Fahrenheit, which released water vapor. “This soil clearly has interacted with water in the past,” said William V. Boynton of the University of Arizona, the lead scientist in this experiment.

Dr. Boynton said he could not say when the liquid water was present or even where it was. The moisture might have come from dust particles that had blown there from other parts of Mars. “At this point, it is difficult to quantify what was given off,” he said.

The oven experiment also found carbon dioxide vapors, not surprising because the planet’s thin atmosphere is primarily carbon dioxide. The data have not revealed any carbon-based compounds.

The Phoenix mission is not directly looking for life on Mars, but rather whether conditions for habitability ever existed. In the wet chemistry experiment, water was mixed into the soil to produce Martian mud. Then the apparatus performed the same sorts of tests that gardeners use to test the condition of their soil.

The pH level was between 8 and 9, Dr. Kounaves said. The pH, or potential of hydrogen, reflects the concentration of hydrogen ions, or acidity, of a substance and usually varies between 0 and 14, with 7 considered neutral. (The water of Earth’s oceans, for comparison, has a pH of 8.2.) The experiment also found the presence of magnesium, sodium, potassium and chloride ions in the soil.