Astronomers often use "false-color" images to better understand deep space phenomena like supernova remnants or nebulae. But false color imagery is also used a bit closer to home -- as evidenced by stunning new photos of the surface of Mars taken by the High Resolution Imaging Science Experiment (HiRISE) camera aboard the Mars Reconnaissance Orbiter.
HiRISE takes pictures in three color bands: 400 to 600 nanometers (blue-green), 550 to 850 nm (red) and 800 to 1,000 nm (near infrared). Since the human eye sees wavelengths from about 390 to 700 nm, HiRISE cross-maps the longer bands to the visible spectrum, creating a false-color image that helps viewers see features more clearly. (Story continues below)
Click Fullscreen For Best Experience
Shallow Irregular Pits with Raised Rims
Researchers are still trying to figure out what caused these "mystery" features. One intriguing theory suggests they were sculpted by ancient glaciation.
Dune Fields and Wall Rock in Coprates Chasma
Researchers think that the dune sand, wall spurs and boulders shown here are all partially composed of olivine, a mineral that is highly susceptible to weathering by aqueous (water) processes.
Sedimentary Bedrock Diversity in Terby Crater
From the HiRISE website: "Terby Crater, sitting on the northern rim of Hellas Basin, has been filled by sedimentary deposits, perhaps deposited by or in water."
Raindrops of Sand in Copernicus Crater
The dark features here look like raindrops, but are actually sand dunes. This spot was targeted an infrared spectrometer on the Mars Orbiter because the dunes are rich in the mineral olivine. Olivine-rich dunes are very rare on Earth, as olivine rapidly weathers to clays in a wet environment. There is also olivine-rich bedrock in the central peaks of Copernicus Crater on the Moon. (Caption: Alfred McEwen)
Bright Tracks from Bouncing and Rolling Boulders
This image shows a well-preserved impact crater. A closeup view highlights distinctive bright lines and spots on the steep slope on the north side. No such pattern was visible when HiRISE imaged this crater 5 years ago (2.6 Martian years ago), in March 2008. The discontinuous bright spots indicate bouncing, thus these features are interpreted to be a result of boulders bouncing and rolling down the slope. Where did the boulders come from? Maybe they fell from the crater's steep upper cliffs, although we don't see any new bright features there that point to the source. Maybe the rocks were ejected from a new impact event somewhere nearby. Why are the trails bright? Perhaps the shallow subsurface soil here is generally brighter than the surface soil, as revealed by the Spirit rover in a part of Gusev Crater. It can't be bright from ice because this is a warm equator-facing slope seen in the summer. (Caption: Alfred McEwen)
Ridges and Grooves That Wave and Buckle on a Valley Floor
Long linear ridges and grooves curve, wave, and buckle across most of this image. Here, as elsewhere on Mars, these linear ridges and grooves fill a valley floor, hence their name, "lineated valley fill." Because these features are only found in valleys in the middle latitudes (30 to 60 degrees) of the Northern and Southern hemispheres, scientists had long suspected that they were associated with some ancient climate that had prevailed in that latitudinal band. Based on peering beneath the surface using radar, scientists now think that lineated valley fill is probably merely a rocky veneer atop a glacier of nearly pure ice! The rocks that make up the linear ridges and grooves were oriented by the ancient flow of the glacier underneath. (Caption: Ethan Schaefer)
Megabreccia on the Floor of an Impact Crater
"'Megabreccia' is a term we use to describe jumbled, fragmented blocks of rock larger than 1 meter across, in a matrix of finer-grained materials," per the HiRISE website. "It's the result of energetic processes, typically from an impact event."
Defrosting of Dunes with Large Gullies
The purpose of this observation is to image dunes where substantial "gullies" formed in the previous Martian winter. These features likely formed due to carbon dioxide defrosting or weight that caused the surface to slump. The gullies at this site are particularly large, which is intriguing, suggesting that this site be monitored to see if stages of gully formation or details of activity can be observed. (Caption: HiRISE Science Team)
Martian Honeycomb Hideout
The most striking aspect of this image is the honeycomb-like pattern of the dunes. This is a seasonal monitoring site, meaning HiRISE takes pictures across the seasons to view what changes occur and what causes them. The surface here is covered with seasonal carbon dioxide frost. In this case, we can compare locations of cracks in the frost to previous images. (Caption: HiRISE Science Team)
In an email to The Huffington Post, HiRISE communications team member Yisrael Espinoza explained that enhanced color imaging helps point out details that might not be as visible in black and white. (The camera's "red" band, which falls within human visual range, is displayed in grayscale on non-enhanced HiRISE images.)
There are variable levels of color enhancement for HiRISE, but a few general observations can be made about colors and the topography they depict. In images such as those seen in the gallery above, "dust ... is generally the reddest material present and looks reddish. ... Coarser-grained materials (sand and rocks) are generally bluer ... but also relatively dark, except where coated by dust." Frost and ice are also relatively blue, but brighter.
HiRISE represents a collaboration between NASA's Jet Propulsion Laboratory and the University of Arizona. It is one of several instruments on the Mars Reconnaissance Orbiter, which was launched in 2005. Together, the instruments on the orbiter "zoom in for close-up photography of the martian surface, analyze minerals, look for subsurface water, trace how much dust and water are distributed in the atmosphere and monitor daily global weather."
Also on HuffPost: