From Newsgroup: alt.astronomy
All images are copyright(c) NASA.
Video Camera Will Show Mars Rover’s Touchdown
Jet Propulsion Laboratory
July 19, 2010
Image 1. Installing the mast on Curiosity. Retrieved July 27, 2010 from
A downward-pointing camera on the front-left side of NASA’s Curiosity
rover will give adventure fans worldwide an unprecedented sense of
riding a spacecraft to a landing on Mars.
The Mars Descent Imager, or MARDI, will start recording high-resolution
video about two minutes before landing in August 2012. Initial frames
will glimpse the heat shield falling away from beneath the rover,
revealing a swath of Martian terrain below illuminated in afternoon
sunlight. The first scenes will cover ground several kilometers (a few
miles) across. Successive images will close in and cover a smaller area
The full-color video will likely spin, then shake, as the Mars Science
Laboratory mission’s parachute, then its rocket-powered backpack, slow
the rover’s descent. The left-front wheel will pop into view when
Curiosity extends its mobility and landing gear.
The spacecraft’s own shadow, unnoticeable at first, will grow in size
and slide westward across the ground. The shadow and rover will meet at
a place that, in the final moments, becomes the only patch of ground
visible, about the size of a bath towel and underneath the rover.
Dust kicked up by the rocket engines during landing may swirl as the
video ends and Curiosity’s surface mission can begin.
All of this, recorded at about four frames per second and close to 1,600
by 1,200 pixels per frame, will be stored safely into the Mars Descent
Imager’s own flash memory during the landing. But the camera’s principal
investigator, Michael Malin of Malin Space Science Systems, San Diego,
and everyone else will need to be patient. Curiosity will be about 250
million kilometers (about 150 million miles) from Earth at that point.
It will send images and other data to Earth via relay by one or two Mars
orbiters, so the daily data volume will be limited by the amount of time
the orbiters are overhead each day.
“We will get it down in stages,” said Malin. “First we’ll have
thumbnails of the descent images, with only a few frames at full scale.”
Subsequent downlinks will deliver additional frames, selected based on
what the thumbnail versions show. The early images will begin to fulfill
this instrument’s scientific functions. “I am really looking forward to
seeing this movie. We have been preparing for it a long time,” Malin
said. The lower-resolution version from thumbnail images will be
comparable to a YouTube video in image quality. The high-definition
version will not be available until the full set of images can be
transmitted to Earth, which could take weeks, or even months, sharing
priority with data from other instruments.”
Image 2. Curiosity. Retrieved July 27, 2010 from
The Mars Descent Imager will provide the Mars Science Laboratory team
with information about the landing site and its surroundings. This will
aid interpretation of the rover’s ground-level views and planning of
initial drives. Hundreds of the images taken by the camera will show
features smaller than what can be discerned in images taken from orbit.
“Each of the 10 science instruments on the rover has a role in making
the mission successful,” said John Grotzinger of the California
Institute of Technology in Pasadena, chief scientist for the Mars
Science Laboratory. “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.”
The nested set of images from higher altitude to ground level will
enable pinpointing Curiosity’s location even before an orbiter can
photograph the rover on the surface.
Malin said, “Within the first day or so, we’ll know where we are and
what’s near us. 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
In addition, combining information from the descent images with
information from the spacecraft’s motion sensors will enable calculating
wind speeds affecting the spacecraft on its way down, an important
atmospheric science measurement. The descent data will later serve in
designing and testing future landing systems for Mars that could add
more control for hazard avoidance.
After landing, the Mars Descent Imager will offer the capability to
obtain detailed images of ground beneath the rover, for precise tracking
of its movements or for geologic mapping. The science team will decide
whether or not to use that capability. Each day of operations on Mars
will require choices about how to budget power, data and time.
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 assembly and testing of the rover and other parts of the Mars
Science Laboratory flight system at NASA’s Jet Propulsion Laboratory,
Pasadena, Calif. 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.
Malin Space Science Systems delivered the Mars Descent Imager in 2008,
when NASA was planning a 2009 launch for the mission. This camera shares
many design features, including identical electronic detectors, with two
other science instruments the same company is providing for Curiosity:
the Mast Camera and the Mars Hand Lens Imager. The company also provided
descent imagers for NASA’s Mars Polar Lander, launched in 1999, and
Phoenix Mars Lander, launched in 2007. However, the former craft was
lost just before landing and the latter did not use its descent imager
due to concern about the spacecraft’s data-handling capabilities during
crucial moments just before landing.
Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.