ASU USGS project: THEMIS Development of sharpest map of Mars' surface properties

A small impact crater on Mars named Gratteri, 4.3 miles (6.9 km) wide, lies at the center of large dark streaks. 

Unlike an ordinary daytime photo, this nighttime image shows how warm various surface areas are. 

Brighter tones mean warmer temperatures, which indicate areas with rockier surface materials. 

Darker areas indicate cooler and dustier terrain. For example, the bright narrow rings scattered across the image show where rocks are exposed on the uplifted rims of impact craters. 

Broad, bright areas show expanses of bare rock and durable crust. Fine-grain materials, such as dust and sand, show up as dark areas, most notably in the streaky rays made of fine material flung away in the aftermath of the meteorite's impact. 

Image courtesy NASA/JPL-Caltech/Arizona State University.

A heat-sensing camera designed at Arizona State University has provided data to create the most detailed global map yet made of Martian surface properties.

The map uses data from the Thermal Emission Imaging System (THEMIS), a nine-band visual and infrared camera on NASA's Mars Odyssey orbiter.

A version of the map optimized for scientific researchers is available at the U.S. Geological Survey (USGS).

The new Mars map was developed by the Geological Survey's Robin Fergason at the USGS Astrogeology Science Center in Flagstaff, Arizona, in collaboration with researchers at ASU's Mars Space Flight Facility.

The work reflects the close ties between space exploration efforts at Arizona universities and the U.S. Geological Survey.

"We used more than 20,000 THEMIS nighttime temperature images to generate the highest resolution surface property map of Mars ever created," says Fergason, who earned her doctorate at ASU in 2006.

"Now these data are freely available to researchers and the public alike."

Surface properties tell geologists about the physical nature of a planet or moon's surface.

• Is a particular area coated with dust, and if so, how thick is it likely to be?
• Where are the outcrops of bedrock? 
• How loose are the sediments that fill this crater or that valley? 

A map of surface properties lets scientists begin to answer questions such as these.

Darker means cooler and dustier
The new map uses nighttime temperature images to derive the "thermal inertia" for areas of Mars, each the size of a football field.

Thermal inertia is a calculated value that represents how fast a surface heats up and cools off.

As day and night alternate on Mars, loose, fine-grain materials such as sand and dust change temperature quickly and thus have low values of thermal inertia.

Bedrock represents the other end of the thermal inertia range: because it cools off slowly at night and warms up slowly by day, it has a high thermal inertia.

"Darker areas in the map are cooler at night, have a lower thermal inertia and likely contain fine particles, such as dust, silt or fine sand," Ferguson says.

The brighter regions are warmer, she explains, and have surfaces with higher thermal inertia. These consist perhaps of coarser sand, surface crusts, rock fragments, bedrock or combinations of these materials.

The designer and principal investigator for the THEMIS camera is Philip Christensen, Regents' Professor of Geological Sciences in the School of Earth and Space Exploration, part of the College of Liberal Arts and Sciences on the Tempe campus.

NB: Four years ago, Christensen and ASU researchers used daytime THEMIS images to create a global Mars map depicting the planet's landforms, such as craters, volcanoes, outflow channels, landslides, lava flows and other features.


"A tremendous amount of effort has gone into this great global product, which will serve engineers, scientists and the public for many years to come," Christensen says.

"This map provides data not previously available, and it will enable regional and global studies of surface properties. I'm eager to use it to discover new insights into the recent surface history of Mars."

As Fergason notes, the map has an important practical side. "NASA used THEMIS images to find safe landing sites for the Mars Exploration Rovers in 2004, and for Curiosity, the Mars Science Laboratory rover, in 2012," she says.

"THEMIS images are now helping NASA select a landing site for its next Mars rover in 2020."

Mars ASU THEMIS camera to get new views of Red Planet

ASU's Thermal Emission Imaging System (THEMIS) is taking regular temperature measurements of the ground as the orbit of NASA's Mars Odyssey spacecraft drifts toward a time of day that will give THEMIS views of Mars around sunrise and sunset. 

This will be the first systematic observations of these times of day in more than a generation. 

Here, THEMIS is imaging the floor of Gale Crater, using its visual wavebands to create a color view of the area where Mars rover Curiosity (too small to be imaged) is exploring for ancient habitable environments. 

Image courtesy NASA /JPL-Caltech /Arizona State University.

For the first time since the Viking Mars mission of the 1970s, which ended more than a generation ago, scientists will soon begin systematic observations of Mars from orbit at times of day around local sunrise and sunset.

The instrument they will use is the Thermal Emission Imaging System (THEMIS) camera, designed at Arizona State University.

Mars Odyssey carries three main science instruments: The Gamma Ray Spectrometer (GRS), the Thermal Emission Imaging System (THEMIS), and the Mars Radiation Environment Experiment (MARIE).

The spacecraft has been drifting toward the new orbit for more than a year, and a small engine burn on Feb. 11 accelerated the drift so it can finalize the orbit in November of 2015.

During the transition, THEMIS will continue observations as the orbital time of day changes.

Philip Christensen

"We don't know exactly what we'll find when we get to an orbit where we see Mars just after sunrise," says Philip Christensen, designer and principal investigator for THEMIS.

He is a Regents' Professor of Geological Sciences in ASU's School of Earth and Space Exploration on the Tempe campus. Christensen developed the post-orbit change observing plan.

THEMIS is a multi-band camera that images Mars in nine infrared (heat-sensitive) "colours" and five visible ones. It was launched on Mars Odyssey in April 2001 and reached the Red Planet in October that year.

The spacecraft spent several months dipping into the Martian atmosphere to regularize its orbit, and THEMIS began science imaging in February 2002.

With more than 12 years elapsed since arrival, Mars Odyssey is the longest-working Mars spacecraft of any nation.


Morning and evening on Mars
Besides revealing landscapes in sharp relief, thanks to the low sun angle, the new orbital time of day for THEMIS promises to let scientists explore frosts, ground fogs, early morning clouds and hazes, and other transient atmosphere-related features that usually vanish as the Martian day goes on.

"We know that in places, carbon dioxide frost forms overnight," says Christensen. "And then it sublimates immediately after sunrise."

"What would this process look like in action? How would it behave? We've never observed this kind of phenomenon directly."

He notes that the Martian atmosphere is more variable than scientists have appreciated in the past.

"We can look for seasonal differences," says Christensen. "Are fogs more common in winter or spring? Do they vary from day to day? From one part of the year to another? From year to year? We'll check it out."

In addition, THEMIS will measure surface temperatures at thousands of locations. These observations can yield insight about materials in the ground and about temperature-driven processes.

These include warm-season flows of water or brine seen on some slopes, and gas-and-sand geysers fed by spring thawing of carbon dioxide ice near Mars' south pole.

Jeffrey Plaut

"We're teaching an old spacecraft new tricks," says Odyssey project scientist Jeffrey Plaut at NASA's Jet Propulsion Laboratory in Pasadena, California.

"We will be in position to do something that has never been done systematically: to watch how morning fog, clouds and surface frost develop at different times of year."

After Mars Odyssey reaches its intended orbit of 6:45 a.m. and p.m. (local time) in November 2015, mission engineers expect Odyssey will have enough propellant for nine to 10 more years of operation, an important matter for ongoing Mars exploration.

Besides conducting its own observations, Odyssey also serves as a crucial communications relay to Earth for the two active rovers, Curiosity and Opportunity, operating on the Martian surface.

"Mars is a dynamic world," says Christensen. "And for a generation, we've not been positioned to explore this part of it so thoroughly."

NASA ARTEMIS Spacecraft Prepares for Lunar Orbit

They've almost arrived. It took one and a half years, over 90 orbit maneuvers, and - wonderfully - many gravitational boosts and only the barest bit of fuel to move two spacecraft from their orbit around Earth to their new home around the moon.

Along their travels, the spacecraft have been through orbits never before attempted and made lovely curlicue leaps from one orbit to the next. This summer, the two ARTEMIS spacecraft - which began their lives as part of the five-craft THEMIS mission studying Earth's aurora - will begin to orbit the moon instead. THEMIS is an acronym for the Time History of Events and Macroscale Interaction during Substorms spacecraft.

The view from above of the ARTEMIS orbits as they make the transition from the kidney-shaped Lissajous orbits on either side of the moon to orbiting around the moon. 

Credit: NASA/Goddard Space Flight Center

Even with NASA's decades of orbital mechanics experience, this journey was no easy feat.

The trip required several maneuvers never before attempted, including several months when each craft moved in a kidney-shaped path on each side of the moon around, well, nothing but a gravitational point in space marked by no physical planet or object.

"No one has ever tried this orbit before, it's an Earth-moon libration orbit," says David Folta a flight dynamics engineer at NASA's Goddard Space Flight Center in Greenbelt, Md. "It's a very unstable orbit that requires daily attention and constant adjustments."

The journey for ARTEMIS - short for Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun - began in 2009, after THEMIS had completed some two years of science data collection on the magnetic environment around Earth, the aurora, and how these are affected by the sun.

The spacecraft are solar-powered, but orbits for the two outermost THEMIS spacecraft had slipped over time and were going to be subjected to regular eight-hour periods of darkness. These spacecraft could withstand up to three hours without sunlight, but this much darkness would soon leave the batteries completely discharged.

Themis on MARS Odyssey captures spectacular Mars map ever

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.

NASA Themis Cluster discovers magnetic Spacequakes

Researchers using NASA's fleet of five THEMIS spacecraft have discovered a form of space weather that packs the punch of an earthquake and plays a key role in sparking bright Northern Lights. They call it "the spacequake."

A spacequake is a temblor in Earth's magnetic field. It is felt most strongly in Earth orbit, but is not exclusive to space. The effects can reach all the way down to the surface of Earth itself.

"Magnetic reverberations have been detected at ground stations all around the globe, much like seismic detectors measure a large earthquake," says THEMIS principal investigator Vassilis Angelopoulos of UCLA.

It's an apt analogy because "the total energy in a spacequake can rival that of a magnitude 5 or 6 earthquake," according to Evgeny Panov of the Space Research Institute in Austria. Panov is first author of a paper reporting the results in the April 2010 issue of Geophysical Research Letters (GRL).

In 2007, THEMIS discovered the precursors of spacequakes. The action begins in Earth's magnetic tail, which is stretched out like a windsock by the million mph solar wind. Sometimes the tail can become so stretched and tension-filled, it snaps back like an over-torqued rubber band. Solar wind plasma trapped in the tail hurtles toward Earth.

On more than one occasion, the five THEMIS spacecraft were in the line of fire when these "plasma jets" swept by. Clearly, the jets were going to hit Earth. But what would happen then? The fleet moved closer to the planet to find out.

"Now we know," says THEMIS project scientist David Sibeck of the Goddard Space Flight Center. "Plasma jets trigger spacequakes."

According to THEMIS, the jets crash into the geomagnetic field some 30,000 km above Earth's equator. The impact sets off a rebounding process, in which the incoming plasma actually bounces up and down on the reverberating magnetic field. Researchers call it "repetitive flow rebuffing."

It's akin to a tennis ball bouncing up and down on a carpeted floor. The first bounce is a big one, followed by bounces of decreasing amplitude as energy is dissipated in the carpet.

"We've long suspected that something like this was happening," says Sibeck. "By observing the process in situ, however, THEMIS has discovered something new and surprising."

NASA Themis Solar Probes Dispatched to Moon

A pair of NASA science satellites that have been studying how solar geomagnetic storms impact Earth are being dispatched to the moon for a new mission.

The probes are part of a constellation of five satellites collectively known as THEMIS, an acronym for Time History of Events and Macroscale Interactions during Substorms, which was launched in February 2007.

The spacecraft, which were carefully positioned in orbit for coordinated measurements downstream of Earth, surpassed their two-year design life and remain operational. But over time, the two outer satellites' orbits would have been in Earth's shadow for prolonged periods, leading to cold temperatures that likely would have been fatal.

"When we realized that the satellites would be going into very deep shadows, we started thinking of different methods for saving them -- even before they were launched," lead scientist Vassilis Angelopoulos, at the University of California, Berkeley, told Discovery News. "We realized that if we had enough fuel to change their orbits, the moon's gravity would start pulling them up."

Funding for the new mission is still pending NASA's approval, but the satellites already are on their way. The first probe is slated to slip into a preliminary orbit around the moon in August; the second one is due to follow in October.

The orbits will be tweaked until April when the recycled spacecraft would be properly positioned for their new mission, called ARTEMIS for Acceleration Reconnection and Turbulence and Electrodynamics of the Moon's Interaction with the Sun.

"This will be the first time we have two identical satellites with full instrumentation to do space physics experiments," Angelopoulos said. "It was actually not difficult to come up with fantastic new science that could be gotten out of this pair."

Scientists want to put the spacecraft as close as about 100 kilometers (62 miles) in front of and behind the moon. From that vantage point, the probes could see what's coming toward the moon from the sun, what's coming out the other side and how the environment of the moon varies in response.

Scientists Finds Evidence Of Water Ice On Asteroid's Surface

Scientists Finds Evidence Of Water Ice On Asteroid's Surface

This image shows the Themis Main Belt which sits between Mars and Jupiter. Asteroid 24 Themis, one of the largest Main Belt asteroids, was examined by University of Tennessee scientist, Josh Emery, who found water ice and organic material on the asteroid's surface. His findings were published in the April 2010 issue of Nature. Credit: Josh Emery/University of Tennessee, Knoxville.

Asteroids may not be the dark, dry, lifeless chunks of rock scientists have long thought.

Josh Emery, research assistant professor with the earth and planetary sciences department at the University of Tennessee, Knoxville, has found evidence of water ice and organic material on the asteroid 24 Themis. This evidence supports the idea that asteroids could be responsible for bringing water and organic material to Earth.

The findings are detailed in the journal "Nature." Using NASA's Infrared Telescope Facility on Hawaii's Mauna Kea, Emery and Andrew Rivkin of Johns Hopkins University in Laurel, Md., examined the surface of 24 Themis, a 200-kilometer wide asteroid that sits halfway between Mars and Jupiter.

By measuring the spectrum of infrared sunlight reflected by the object, the researchers found the spectrum consistent with frozen water and determined that 24 Themis is coated with a thin film of ice. They also detected organic material.

"The organics we detected appear to be complex, long-chained molecules. Raining down on a barren Earth in meteorites, these could have given a big kick-start to the development of life," Emery said.

Emery noted that finding ice on the surface of 24 Themis was a surprise because the surface is too warm for ice to stick around for a long time.