CTX (Context Camera) makes observations simultaneously with high-resolution images collected by HiRISE and data collected by the mineral-finding CRISM spectrometer.
As its name suggests, CTX provides the wider context for the data collected by the other two instruments. Scientists examine details of rocks and mineral fields with the other instruments, while CTX provides a bigger-picture view of the terrain.
Together HiRISE, CRISM, and CTX are an extremely powerful tool set. For example, many of the layered terrains observed by the Mars Orbital Camera on the Mars Global Surveyor spacecraft could be water-deposited sediments. They could also be layers of volcanic lavas, ash, or wind-deposited sediments. By combining information about small-scale layers from HiRISE, the geologic context from CTX, and the mineralogical information from CRISM, scientists can distinguish between these possibilities.
From 400 kilometers (250 miles) above Mars, CTX takes images spanning 30 kilometers (almost 19 miles) of terrain. The camera has a resolution of 6 meters per pixel.
The team lead and supplier of CTX is Mike Malin from Malin Space Science Systems.