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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