An artist’s impression of the Phoenix Mars Lander entering the Martian atmosphere, obtained from Nasa

Los Angeles, May 24: Nasa scientists have spoken of their fears for their latest mission to Mars, worried that five years of meticulous preparation are about to culminate in “seven minutes of terror”.

If all goes according to plan, tomorrow the Phoenix Mars Lander will make its perilous descent after a 422 million mile, nine-month journey across space and begin three months of ground-breaking research, seeking evidence of life on the Red Planet.

But the prospect of witnessing the seven-minute, white-knuckle landing procedure has left the scientists in charge of the mission with frayed nerves. The unmanned craft must complete a breathtaking sequence of manoeuvres after crashing into the planet’s thin atmosphere at almost 13,000mph if it is to touch down on the icy ground intact.

The spectre of earlier unsuccessful missions to Mars hangs over the £215 million project to excavate unexplored terrain near the planet’s north pole.

“It will be a nerve-wracking time on Sunday for all of us,” said Fuk Li, Mars Exploration Programme manager at Nasa’ Jet Propulsion Laboratory (JPL) in Pasadena, California. He described the highly risky manoeuvre as “one of the most difficult things robotic missions have to do” but “a risk worth taking” were it to prove a success.

“It’s very terrifying,” added Barry Goldstein, Phoenix project manager at JPL, who said the team’s shorthand for tomorrow’s entry, descent and landing (EDL) was “seven minutes of terror”.

“If everything goes perfectly,” he said, the Phoenix could be beaming back “postcard images” of its new home within hours. “But that’s a big ‘if’ with a capital I and a bigger F.”

Should the landing go as planned, ground controllers expect to hear the first signal Sunday evening local time.

But despite biting their nails to the quick, mission controllers are confident the probe can pull off its perilous descent and embark on ground-breaking research in the planet’s northern plains. The weather forecast is good and the spacecraft on target to hit its target landing site.

After jettisoning the “cruise stage” on which it has journeyed from the Earth, the lander will enter the top of the Martian atmosphere, activate its heat shield and slow to around 1,000mph before deploying a parachute to cut its speed to around 125mph.

The craft, which is just seven feet tall, 18 feet wide and weighs 772lbs, then embarks on several seconds of freefall — “where it really gets exciting,” according to Ed Sedivy, programme manager at Lockheed Martin, which built the Phoenix.

Twelve rocket thrusters will then slow the craft to 5mph, echoing a scene from an episode of Thunderbirds, and the probe’s three legs make gentle contact with the planet’s dusty floor. It will then embark on a search for signs of life in the reservoirs of ice beneath Mars’s frigid north pole.

Mission controllers are to spend the next three months living on Mars time. A sol, as a Martian day is known, is about 40 minutes longer than a day on the Earth and the 60-odd members of the team tracking the probe from JPL, Arizona and Lockheed Martin will all switch over to Red Planet time from tomorrow.

Peter Smith, a planetary geologist at the University of Arizona and lead investigator of the Phoenix science team, said the team would have Martian watches. “We want to be on the same time schedule as our equipment and we will be on Mars time throughout the summer.”