NASA Spacecraft Camera Yields Most Accurate Mars Map

PASADENA, Calif. -- A camera aboard NASA's Mars Odyssey spacecraft has helped develop the most accurate global Martian map ever. Researchers and the public can access the map via several websites and explore and survey the entire surface of the Red Planet.

The map was constructed using nearly 21,000 images from the Thermal Emission Imaging System, or THEMIS, a multi-band infrared camera on Odyssey. Researchers at Arizona State University's Mars Space Flight Facility in Tempe, in collaboration with NASA's Jet Propulsion Laboratory in Pasadena, Calif., have been compiling the map since THEMIS observations began eight years ago.

The pictures have been smoothed, matched, blended and cartographically controlled to make a giant mosaic. Users can pan around images and zoom into them. At full zoom, the smallest surface details are 100 meters (330 feet) wide. While portions of Mars have been mapped at higher resolution, this map provides the most accurate view so far of the entire planet.

The new map is available at: http://www.mars.asu.edu/maps/?layer=thm_dayir_100m_v11 .

Advanced users with large bandwidth, powerful computers and software capable of handling images in the gigabyte range can download the full-resolution map in sections at: http://www.mars.asu.edu/data/thm_dir_100m .

"We've tied the images to the cartographic control grid provided by the U.S. Geological Survey, which also modeled the THEMIS camera's optics," said Philip Christensen, principal investigator for THEMIS and director of the Mars Space Flight Facility. "This approach lets us remove all instrument distortion, so features on the ground are correctly located to within a few pixels and provide the best global map of Mars to date."

Working with THEMIS images from the new map, the public can contribute to Mars exploration by aligning the images to within a pixel's accuracy at NASA's "Be a Martian" website, which was developed in cooperation with Microsoft Corp. Users can visit the site at: http://beamartian.jpl.nasa.gov/maproom#/MapMars .

"The Mars Odyssey THEMIS team has assembled a spectacular product that will be the base map for Mars researchers for many years to come," said Jeffrey Plaut, Odyssey project scientist at JPL. "The map lays the framework for global studies of properties such as the mineral composition and physical nature of the surface materials."

Other sites build upon the base map. At Mars Image Explorer, which includes images from every Mars orbital mission since the mid-1970s, users can search for images using a map of Mars at: http://themis.asu.edu/maps .

"The broad purpose underlying all these sites is to make Mars exploration easy and engaging for everyone," Christensen said. "We are trying to create a user-friendly interface between the public and NASA's Planetary Data System, which does a terrific job of collecting, validating and archiving data."

Mars Odyssey was launched in April 2001 and reached the Red Planet in October 2001. Science operations began in February 2002. The mission is managed by JPL for NASA's Science Mission Directorate in Washington. Lockheed Martin Space Systems in Denver is the prime contractor for the project and built the spacecraft. NASA's Planetary Data System, sponsored by the Science Mission Directorate, archives and distributes scientific data from the agency's planetary missions, astronomical observations, and laboratory measurements.

Solar Activity Is Ramping Up

The Sun is finally awakening from its unusually long minimum. While it isn't rife with spots and flares, it seems that lately at least one sunspot, active region, or interesting prominence is now gracing our star on a weekly basis.

Today, AR 1087 is crackling with minor flares, and those of you with any kind of solar filter will be treated to a respectable show whenever it's clear. (For a real treat, check out this video recorded by the Solar Dynamics Observatory.)

I've recently dusted off my trusty Coronado PST (which hardly saw any action over the past two years) and have been rewarded with some excellent prominences and swirling filaments. Every clear day has been worth taking a solar break over the past two weeks alone; last week, AR 1084 paraded across the solar surface, presenting a nearly perfect spiral of plasma traveling along its unusually stable magnetic field.

Prominences and filaments (prominences that cross the solar disk) have been bigger lately too; over the July 4th weekend, I was able to wow my friends and relatives with views of a large prominence as it slowly detached from the solar disk and blew away into space.


The picturesque sunspot AR 1084 recorded in white light using a Baader Herschel Wedge on July 5th.

If AR 1087 doesn't fizzle out this week, I'm hoping it produces a strong eruption in Earth's direction, which may result in auroras visible from my backyard in Manchester, New Hampshire. If you'd like to keep an eye on the Sun, frequently check Spaceweather.com, or for an up-to-the-minute, full-disk image of the Sun in hydrogen light, check out this link to see if it's worth pulling out your solar equipment. You can also follow me on Facebook; I usually post my latest images there whenever I catch something interesting. Please be safe, and only view the Sun through an appropriate solar filter.

South Pacific Eclipse

On Sunday, July 11th, the new Moon will pass directly in front of the sun, producing a total eclipse over the South Pacific. The path of totality stretches across more than a thousand miles of ocean, making landfall in the Cook Islands, Easter Island, a number of French Polynesian atolls, and the southern tip of South America

"It's going to be a beautiful sight," says Lika Guhathakurta of NASA's Heliophysics Division in Washington DC. She herself has witnessed more than eight solar eclipses in a variety of environments from busy cities to lonely deserts to remote mountain peaks. "The South Pacific eclipse could top them all."


South Pacific Eclipse (Mir shadow)
As seen from space station Mir, the Moon's shadow sweeps across Earth during an eclipse in 1999.

She imagines how the event will unfold: First, the Moon's cool shadow will sweep across the landscape, bringing a breeze of its own to compete with the sea's. Attentive observers might notice shadow bands (a well-known but mysterious corrugation of the Moon's outermost shadow) rippling across the beach as the temperature and direction of the wind shift. The ensuing darkness will have an alien quality, not as black as genuine night, but dark enough to convince seabirds to fly to their island roosts. As their cries subside, the sounds of night creatures come to the fore, a noontime symphony of crickets and frogs.

Next comes the moment that obsesses eclipse chasers: The corona pops into view. When the Moon is dead-center in front of the sun, mesmerizing tendrils of gas spread across the sky. It is the sun's outer atmosphere on full display to the human eye.

"You can only see this while you are standing inside the shadow of the Moon," says Guhathakurta. "It is a rare and special experience."

Because the sun's atmosphere is constantly shape-shifting, every total eclipse is unique. Predicting what any given one will look like can be tricky.


South Pacific Eclipse (corona)
The sun's corona shows itself during the total solar eclipse of March 29, 2006.

Nevertheless, Guhathakurta is making a prediction. It's based on a new development in solar physics. For the first time, NASA has two spacecraft stationed on opposite sides of the sun. "STEREO-A and STEREO-B are giving us a realtime 3D view of the solar corona, something we've never had before," she explains. "This helps forecast the appearance of the corona during an eclipse."

Inspecting images from STEREO and also from the Solar and Heliospheric Observatory (SOHO), she predicts observers could see four ghostly-white streamers, two on either side of the sun. They will stretch out two to three degrees, forming a gossamer "X" in the sky with a black hole at the crossing point.

"I'm prepared to be wrong," she confesses. "This is the first time anyone has tried to make such a forecast using STEREO data. It will be interesting to see if it works."

STAR TRAK

The western sky will be crowded after sunset in July. Forming a long slanting line from highest to lowest above the horizon will be the planets Saturn, Mars and Venus, with the bright star Regulus included as well.

Brilliant white Venus will dominate the scene, shining low in the west-southwest an hour after sunset. The gleaming planet will be 40 times brighter than the most conspicuous stars in the evening sky. Venus will become even more dazzling as the month passes, far outshining the stars of the constellation Leo the Lion as it moves among them. On July 9, Venus will be just a degree north of Leo's brightest star, Regulus. By month's end, Venus will be closing in on Mars and Saturn to its upper left (south).

Mars, a hundred times fainter than Venus, will be easy to identify by its red-orange color, contrasting with the pale yellow of Saturn farther to the left. The two will be well separated at the start of the month, but the gap between them will close rapidly, and they will be only a couple of degrees apart at month's end. Mars will not show much detail in a telescope, but Saturn's rings and larger moons will put on a good show starting about an hour after sunset.

Around the middle of the month, Mercury will emerge from the afterglow of sunset low in the west-northwest, adding a fourth planet to the celestial chorus line. Mercury will be very close to Regulus on the evening of July 27. Binoculars may be needed to see this conjunction.

Jupiter will rise around the time Saturn sets, a little after midnight at the start of the month and about 10:30 p.m. EDT by month's end. Appearing well above the eastern horizon as a beautiful "morning star" in the brightening sky, Jupiter will get higher and brighter as the month passes. Its four largest moons will be on the same side of the planet on July 5, 8 and 18.