ISRO’s Mars images

Figure (i)

EARLY this month, the Indian Space Research Organisation released some spectacular images of Mars as observed by the instruments aboard its Mars Orbiter Mission (MOM) spacecraft, which include views of a canyon, volcanic deposits and reflectance or albedo features of the Martian surface. The images and captions describing them are:

(i) Images of Valles Marineris and adjoining regions of Mars taken by the Mars Colour Camera (MCC) on board MOM on February 5 at a spatial resolution of 1.2 kilometres from an altitude of 24,000 km.

Valles Marineris is the largest canyon system on Mars, about 4,000 km long, 200 km wide and 7 km deep. This image also shows Noctis Labyrinthus at the bottom left corner of the image. Fracture patterns at the centre of Valles Marineris and the northern portion of Noctis Labyrinthus are clearly seen at this resolution.

(ii) Images of the Eos Chaos region of Mars taken by the MCC at a spatial resolution of 220 metres from an altitude of 4,403 km. Eos Chaos is located in the eastern part of the Valles Marineris region. Grabens/fracture patterns at the edges of Valles Marineris are clearly seen at this resolution. Images at this coarse resolution are useful for understanding geological processes at regional scale.

(iii) Three-dimensional view of Arsia Mons created by draping the MCC image on topography of the region derived from the Mars Orbiter Laser Altimeter. This image of the Arsia Mons region taken by the MCC on January 4 at a spatial resolution of 556 m from an altitude of 10,707 km. Volcanic deposits located at the flanks of the Mons are seen in this image.

(iv) The Methane Sensor for Mars (MSM) payload on board MOM is intended to detect the presence of methane and measure the column density of the same. One of the secondary objectives of this payload is to measure the reflectance of Martian surface in 1.65 microns. The MSM has two channels, methane and reference to measure the radiance from the surface of Mars.

All planets in the solar system receive the sun’s radiation to varying degrees depending on their distance from the sun. Observing the surface of the planet depends on how this radiation is reflected back. Reflected solar radiation from Mars is a diagnostic signal of the planet which provides a lot of information about the planet’s surface as well as its atmosphere.

When we measure the radiance in a specific wavelength of light (in this case, 1.65 microns), then we can generate a reflectance map.

The map presented here shows the surface reflectance of Mars as viewed at 1.65 microns from the reference channel of the MSM up to December 16, 2014. In the map, the blue colour indicates low albedo features and the red shows high albedo features on the Martian surface. The map resolution is 0.5°x 0.5° in latitude-longitude.