NASA
has added a video camera to its next Mars rover to take viewers on Earth along
for the ride when the six–wheeled robot lands on the Martian surface.
Called
the Mars Descent Imager, or MARDI, the camera is on the front-left side of the Mars
Science Laboratory Curiosity and should record high-resolution video
approximately two minutes before the rover's planned landing on Mars in August
2012. The rover is slated to launch toward Mars next year.
If
all goes well, the initial video views should show Curiosity's heat shield
falling away from beneath the rover, revealing a swath of Martian terrain
below, illuminated in afternoon sunlight, rover officials said. The first
scenes would cover ground a few miles across. Subsequent images will close in
and cover a smaller area each second.
Viewers
should, however, prepare for a bumpy ride.
The
full-color video will likely spin and shake as Curiosity's parachute - and
later its rocket-powered backpack - work to slow the rover's descent, according
to a NASA description. The left-front wheel should then come into the field of
view when Curiosity extends its mobility and landing gear, after which Curiosity's surface mission can begin.
The
landing will be recorded at approximately four frames per second and at a
resolution of about 1,600 by 1,200 pixels per frame. The footage will be
safely stored in the Mars Descent Imager's own flash memory during the landing.
A
relay of information
Curiosity,
which will be about 150 million miles (250 million km) from Earth on landing
day, is expected to beam images and other data back to Earth via relay by one
or two Mars orbiters. The daily data volume will also be limited by the amount
of time the orbiters spend overhead each day.
"We
will get it down in stages," said Michael Malin of Malin Space Science
Systems, the San Diego, Calif.-based company that built the Mars Descent Imager.
"First we'll have thumbnails of the descent images, with only a few frames
at full scale."
Subsequent
downlinks of the data will deliver additional frames, which will be selected
based on what the thumbnail versions display.
"The
lower-resolution version from the thumbnail images will be comparable in image
quality to a YouTube video," Malin said. "The high-definition
version, however, will not be available until the full set of images can be
transmitted to Earth, which could take weeks, or even months, as it shares
priority with data from other instruments."
A
glimpse at the surroundings
The
Mars Descent Imager will also provide the Mars Science Laboratory team with
information about the landing site and its surroundings. This will help mission
scientists interpret the rover's ground-level views and help them plan its initial drives.
"Each
of the 10 science instruments on the rover has a role in making the mission
successful," said Curiosity's chief scientist John Grotzinger of the
California Institute of Technology in Pasadena, Calif. "This one will give
us a sense of the terrain around the landing site and may show us things we
want to study. Information from these images will go into our initial decisions
about where the rover will go."
Hundreds
of images taken by the camera will show features smaller than what can be
discerned in images taken from orbit. The set of images from higher altitude to
ground level will allow scientists to pinpoint Curiosity's location even before
an orbiter can photograph the rover on the surface.
"Within
the first day or so, we'll know where we are and what's near us," Malin
said. "MARDI doesn't do much for six-month planning – we'll use orbital
data for that – but it will be important for six-day and 16-day planning."
But
wait, there's more
Combining
information from the descent images with information from the spacecraft's
motion sensors will also enable calculations of wind speeds that affect the
spacecraft on its way down, giving scientists important atmospheric science
measurements.
The
descent data will then play a part in designing and testing future landing systems for Mars that could increase control and hazard
avoidance.
After
landing, the Mars Descent Imager will offer the capability to obtain detailed
images of the ground beneath the rover in order to precisely track its
movements, or for purposes of geologic mapping. Whether this capability is
actually used will be decided by the science team, who will be tasked with
managing budget, data and time constraints.
Last
month, spacecraft engineers and technicians re-installed the Mars Descent
Imager onto Curiosity for what is expected to be the final time as part of the assembly and testing of the rover and its flight system at NASA's Jet Propulsion Laboratory
in Pasadena.
Besides
the rover itself, the flight system includes the cruise stage for operations
between Earth and Mars, and the descent stage for getting the rover from the
top of the Martian atmosphere safely to the ground.
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