May 22, 2008

Phoenix Mars Lander: Step-by-Step Martian Landing Guide

It's go
time for NASA's Phoenix Mars Lander.

After nearly
10 months speeding across 422 million miles (679 million km), the Phoenix
spacecraft is just days away from plunging
into the Martian atmosphere
on Sunday to land near the north pole of Mars.

"We've been
working quite hard all the way along," said Deborah Bass, Phoenix's deputy principal
investigator at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "The
feeling around here is that we are cautiously optimistic."

Phoenix is
slated to land on the Martian arctic plains in a region called Vastitas
Borealis, where it will use a robotic arm to dig
for water ice
in the hopes of determining whether the site may have once
been capable of supporting primitive life.

NASA's Phoenix
mission machine kicks into high gear today at 2:30 p.m. EDT (1830 GMT) with the
first in a series of status briefings leading up to the first hoped-for
signal from the probe at 7:53 p.m. EDT (2353 GMT) on Sunday. Because of the 171
million miles (275 million km) between Mars and Earth during Phoenix's red
planet arrival, it will take signals about 15 to 20 minutes to reach NASA's control
center at JPL once they're sent.

working at night, because that's when the spacecraft is going to land," Bass
told, adding that the entire Phoenix team should now be in
place at JPL and at a primary mission control center at the University of
Arizona, Tucson. "This will be just an absolutely thrilling experience."

for a detailed, minute-by-minute account of Phoenix's landing day.

Phoenix is
the first spacecraft to attempt a powered landing on Mars since the crash of
NASA's ill-fated Mars Polar Lander in 1999. It follows the 2004 airbag-cushioned arrivals
of the agency's Spirit and Opportunity - which are still active today - and would
mark the first successful powered landing on Mars since NASA's two Viking
spacecraft arrived in 1976.

planet rundown

While mission
engineers and researchers have worked diligently over the last 10 months to rehearse
Phoenix's landing day
, the pace will definitely pick up leading into this

On Saturday,
Phoenix researchers and engineers will hold another mission update at 3:00 p.m.
EDT (1900 GMT), which like today's will be broadcast live on NASA TV.

Later that
night, at about 10:46 p.m. EDT (0246 May 25 GMT), Phoenix may fire its thrusters
to tweak its approach toward the Martian arctic.

course correction is available on Sunday - landing day - at 11:46 a.m. EDT (1546
GMT), followed by a 3:00 p.m. EDT (1900 GMT) mission briefing before NASA kicks
off continuous live coverage at 6:30 p.m. EDT (2230 GMT).

For cable
television subscribers without NASA TV or computer access for NASA's Sunday webcast, the
Science Channel will also provide live Phoenix landing coverage and commentary from 7:00-9:00 p.m.
EDT (2300-0100 GMT). Phoenix, itself, will bounce signals off NASA and European
spacecraft orbiting Mars to send data and telemetry back home.

Crunch time
for the Phoenix Mars Lander comes at 7:39 p.m. EDT (2339 GMT) on Sunday, when
the spacecraft separates from its cruise stage and is only 14 minutes away from
its planned touchdown on the Martian surface.

"There are
a lot of events," said Barry Goldstein, Phoenix project manager at JPL. "We
fire 26 pyrotechnic events in the last 14 minutes of this vehicle, and each of
those has to work perfectly for this mission to come off as we've planned."

Phoenix is
due to slam into the Martian atmosphere at 7:46:33 p.m. EDT (2346:33 GMT) while
traveling at 12,600 mph (20,277 kph), beginning a seven-minute
that will be over well before mission controllers on Earth get
their first hint that it even began. The probe is expected to deploy its
parachute about four minutes later, then drop free at 7:50:15 p.m. EDT (2350:15
GMT), then drop free a few minutes later to fire its pulse rocket engines for
the final landing approach.

If all goes
well, the first hint of a successful landing will come at 7:53:52 p.m. EDT
(2353:52 GMT), though Phoenix will have to wait 15 minutes for the dust to
settle before deploying its vital power-generating solar panels, mission
managers have said.

"Our highest
goal is to see if this might form a habitable environment on Mars," said Peter
Smith, Phoenix's principal investigator at the University of Arizona, Tucson. "There's
no signpost today that tells you where to land, and that will be life. So we're
taking a chance."

first Phoenix mission briefing will be broadcast live on NASA TV, beginning
with a mission briefing today at 2:30 p.m. EDT (1830 GMT). Click
for's Phoenix mission coverage and a link