NASA's Odyssey orbiter for the first time has taken a look at the Phobos and has successfully produced a colour-coded image. This is one of the longest-lived missions to Mars and has revealed surface temperatures of the Martian moon considered to be a potential future human-mission outpost.
The Thermal Emission Imaging System (THEMIS) camera on NASA's Mars Odyssey orbiter observed Phobos on September 29. Researchers combined visible-wavelength and infrared data to produce an image colour-coded for surface temperatures of this moon, which has been considered for a potential future human-mission outpost.
"Although THEMIS has been on Mars for 16 years, this was the first time we have been able to turn the spacecraft around to look at Phobos," said Jonathon Hill, THEMIS Mission Planner.
"This half-moon view of Phobos was chosen because it allowed us to observe a wide range of temperatures on the surface," said Hill. Phobos has an oblong shape with an average diameter of about 22 kilometres.
Cameras on other Mars orbiters have previously taken higher-resolution images of Phobos, but none with the infrared information available from THEMIS.
Observations in multiple bands of thermal-infrared wavelengths can yield information about the mineral the composition of the surface, as well as the surface texture.
One major question about Phobos and Mars' even smaller moon, Deimos, is whether they are captured asteroids or bits of Mars knocked into the sky by impacts.
Compositional information from THEMIS might help pin down their origin. Since Odyssey began orbiting the Red Planet in 2001, THEMIS has provided compositional and thermal properties information from all over Mars but never before imaged either Martian moon.
The observation was completed to validate that the spacecraft could safely do so, as the start of a possible series of observations of Phobos and Deimos in coming months.
In the information provided it has revealed about how quickly the ground warms and cools.
The stunning new images were revealed on Sept 29, NASA has combined the visible-wavelength and infrared data to show the surface colour-coded by temperature.
Part of the observed face of Phobos was in pre-dawn darkness, part in morning daylight,’ said THEMIS Deputy Principal Investigator Victoria Hamilton of the Southwest Research Institute.
‘Including a predawn area in the observation is useful because all the heating from the previous day’s sunshine has reached its minimum there.
‘As you go from predawn area to morning area you get to watch the heating behaviour. If it heats up very quickly, it’s likely not very rocky but dusty instead.’
By reading the photo from left to right, it reveals a sequence of times of day, from pre-dawn through sunrise, and long after dawn, according to NASA.
NASA says that the image can help bring a greater understanding of how quickly the surface of Phobos cools and heats up, which can, in turn, provide information about the moon's texture and composition. "As barefoot beach walks can confirm, and warms or cools quicker than rocks or pavement," says the space agency.
While Odyssey is only about 250 miles (400 km) from the surface of Mars, Phobos orbits about 3,700 miles (6,000 km) above the planet, which accounts for the relatively small size of the image.
With PTI Input
Mars Odyssey orbiter
Death Star moon Phobos