Donna Weaver 410-338-4493 Editor's Note: The New Hubble Pictures are Posted Here.
The Hubble Space Telescope will be pointed at Mars this week to make two color photographs of the red planet during its historic close approach to Earth. The pictures are being billed, in advance, as the best pictures of Mars ever taken from Earth or its vicinity.
"The Hubble pictures will provided the sharpest views of Mars ever seen by a telescope located at Earth," said Ray Villard, news director at the Space Telescope Science Institute, which operates Hubble. "Though the Mars orbiters routinely yield stunning close-up views, we'll be treated to a gorgeous pole-to-pole global snapshot of the planet."
The first portrait of Mars will be taken Tuesday night and released at 6 a.m. ET (1100 GMT) Wednesday, Aug. 27. It will be accessible from the SPACE.com home page shortly thereafter.
A second image will be snapped around 5:51 a.m. ET Wednesday morning -- just as Mars is closer than it has been in nearly 60,000 years -- and released at 4 p.m. ET (2100 GMT). That image, too, will be available on SPACE.com as quickly as possible.
Not just point-and-shoot
The lag time for getting the space photography ready for public consumption is due to the complex process involved in downloading data from the orbiting observatory and putting an image together, Villard explained.
"When you think of a telescope you think of point-and-shoot," he said in a telephone interview. "We don't work that way."
Hubble does not make color pictures directly. Rather, it collects at least three grayscale images that are later combined and colorized in the popular Photoshop software program. For each the two historic Mars pictures, Hubble will make 10 separate observations, using different filters, over a 45-minute period.
Mars will rotate on its axis significantly during that 45 minutes, requiring image processors to spend a good amount of time correcting for the fact that each exposure will be slightly offset with respect to the others. The frames must be registered.
Scientists know in advance exactly what face Mars will present.
The first picture will include the Hellas Basin, a giant impact crater. The basin is about 1,240 miles across (2,000 kilometers) and some 4.4 miles (7 kilometers) deep. Even given Mars' thin atmosphere, the Hellas Basin is sometimes blurry because its incredible depth means there is more air in it. It is also frequently clouded over and thus even more obscured.
Clouds from the Hellas Basin are known to spill out and serve as seeds for dust storms that rage on Mars. Scientists do not understand exactly how or why this happens.
The second image will show off Mars' big scar, Valles Marineris, a system of deep canyons that stretch for 2,485 miles (4,000 kilometers) -- roughly equal to the distance between Los Angeles and New York. It will also focus on four prominent volcanoes in a region called the Tharsis Bulge.
The decision to use Hubble to shoot Mars was based partly on the tremendous public interest in the close approach, but the pictures are expected to yield important scientific data, too.
The Hubble advantage
Jim Bell, a Cornell University astronomer who will use the images to study Mars' surface and atmosphere, said only Hubble can provide needed data in ultraviolet and near-infrared wavelengths of light. Spacecraft orbiting Mars image the planet in visible light and far infrared, he said. Further, UV imaging can't be done from the surface of Earth.
Hubble has "an enormous advantage" compared to the orbiters, Bell said.
"These aren't just for pretty pictures," Villard said. He's well aware, though, that the rest of the world awaits nothing less than typical Hubble beauty, and he expects the venerable observatory to deliver on that expectation.
Mars and Earth will be close because the red planet is at opposition. Earth and Mars are on the same side of the Sun. Oppositions occur every 26 months, but this one is special because Earth is about as far as it gets from the Sun on its non-circular orbit, and Mars is about as close to the Sun as it can be.
Hubble is a joint project of NASA and the European Space Agency. It previously photographed Mars during a less impressive opposition in 2001. Hubble also imaged Mars during a planet-wide dust storm that year.
Hubble will get a better view this week than it's ever had of Mars.
"At closest approach on the 27th we'll see surface features as small as 17 miles across," Villard said. "At this resolution the residual southern polar cap and northern polar hood of winter clouds should look quite interesting too."
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