NASA has cleared
the space shuttle Discovery and its crew of seven astronauts for their planned Saturday
landing after giving the spacecraft a clean bill of health today.
Mission
managers declared Discovery fit for landing after a detailed analysis of data
from a final heat shield check performed by the astronauts on Thursday.
"That is
great news," Discovery
skipper Lee Archambault radioed Mission Control after hearing the news. "We
appreciate you passing that along."
Archambault
and his crew are due to land on a runway at NASA's Kennedy Space Center in
Florida at 1:39 p.m. EDT (1739 GMT) to end a 13-day flight that delivered the last
pair of solar arrays to the International Space Station.
The new
solar wings completed the station's power grid and are expected to help the
outpost support larger crews that can, in turn, perform more scientific
research. During the flight, Discovery's crew delivered a vital part for the
space station's new system to recycle astronaut urine, sweat and cabin
condensation into drinking water in order to support larger crews.
The shuttle
is also ferrying NASA
astronaut Sandra Magnus back to Earth after a 4 1/2-month stay at the
station. Her replacement, Japanese astronaut Koichi Wakata, launched to the
station aboard Discovery on March 15 and will stay aboard the outpost for three
months. Magnus will use a special recumbent seat that will allow her to sit in
a reclined position during the descent to ease her return to gravity.
Prepared
for landing
On Friday,
Archambault and shuttle pilot Dominic "Tony" Antonelli checked Discovery's flight
control systems and thrusters to prime the spacecraft for its return to Earth.
They planned to practice landing Discovery on a computer-based simulator later
today.
The shuttle
crew also discussed their mission with students at the Punahou School in
Honolulu, Hawaii, President Barack Obama's
high school alma mater. The spaceflyers spoke with President Obama before
departing the space station.
Discovery astronauts told the students they were proud to have helped the space station reach
full power. They also advised any students interested in becoming astronauts to
study hard in math and science, but also keep their sense of wonder.
"You have
to like exploration and discovery," mission specialist John Phillips said. "If
those are your passion, then this could be a good job for you."
Shuttle
entry flight director Richard Jones said the weather outlook at Discovery's
Cape Canaveral, Fla., landing strip is very favorable. NASA prefers to land its
shuttles at the Florida spaceport to avoid the extra time and cost of ferrying
orbiters from a backup runway in California.
Landing experiment
on tap
Jones said
scientists are also interested in a specific heat-resistant tile, one of the
thousands lining the Discovery's underbelly, which has been intentionally flawed
as
part of an experiment.
Made of a
new type of material called BRI-18, the tile has a slight protuberance to serve
as a "speed bump" during Discovery's re-entry that will interrupt the otherwise
smooth hypersonic flow of superheated air around it. The bump does not pose a
safety risk to the shuttle or its crew, mission managers said.
The bump is
located near the rear of Discovery's left wing and is about 4 inches (10 cm) long
and just over a quarter-inch (0.76 cm) wide. A series of temperature sensors
will record the extra heating aft of the bump to study the hypersonic air flow
and tile for to aid the heat shield design of NASA's space shuttle successor,
the Orion Crew Exploration Vehicle.
A Navy
chase plane will observe Discovery's re-entry from below the spacecraft using a
long-range infrared camera as the shuttle flies over the Caribbean at about Mach
15, Jones said.
"There's a
lot of people that are interested in seeing that data," Jones said.
SPACE.com
is providing continuous coverage of Discovery's STS-119 mission with reporter Clara Moskowitz and senior editor Tariq
Malik in New York. Click
here for mission updates and SPACE.com's live NASA TV video feed.
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