Red planet, in black and white
This weekend, the Phoenix Mars craft sent home pictures that suggest it might have landed right on top of an ice patch. The images show chunks of a white material that scientists said yesterday may be frozen water that was originally hidden beneath a layer of dust. When the Phoenix’s thrusters kicked in right before it touched down on Mars, the blast must have blown the dirt away, revealing the ice, they said.
I’ll take their word for it, because while all of these black-and-white pictures are striking, they’re a little hard to make out. How come the 18-year-old Hubble telescope can capture the heavens in rich color, while the cutting-edge Phoenix lander is stuck taking snapshots in gray scale?
I did some snooping around and found that the scientists want it that way – for now at least.
These early photos are low-res engineering images. They’re a first priority for the mission because they are small files and easy to send back to Earth. The black-and-whites allow the NASA team to quickly survey the area and scan the spacecraft for damage.
A few recent snapshots have a touch of red, but they are just colored for effect. The spacecraft’s camera can take pictures in stereo – half through one infrared filter and half through another color. But this setting is designed for scientific accuracy – not color accuracy. So the tints and hues are only approximations.
Another batch showed cyan-tinted rocks; these color distortions are to help the NASA team distinguish different types of terrain. NASA says it will always mention any false coloring in the captions of its pictures.
The Phoenix camera can switch among 12 different filters – each revealing different colors and different information – and soon will start taking pictures in full color. “Be patient!” says a NASA team member, writing on the lander’s official Twitter log.
Another question I had: How do the photos get to Earth? Once captured, the digital image beams “at about 15 kilobytes a second via an UHF antenna to two spacecraft orbiting Mars,” reports Wired. “The orbiters relay the data to NASA's Deep Space Network antenna arrays in Canberra Australia, Madrid, and in California's Mojave Desert. Raw images are sent to the Jet Propulsion Laboratory and posted to the Phoenix Mars Mission website.”