Today, I will give an overview on some interesting tidbits and an insider look about the HiRISE camera onboard the MRO.
For quick reference:
MRO: Mars Reconnaissance Orbiter
HiRISE: High Resolution Imaging Science Experiment
In 2006, MRO settled into orbit around Mars. It has been running for about 12 years now! Meaning the lifespan has exceeded the primary science goal by approximately 10 years. This is among the longest running space exploration projects to date. Although HiRISE/MRO sometimes runs into troubles, like defaulting into safe mode, it largely has been been an enormous success. Our understanding of the surface of Mars has been greatly increased by it's presence. A few other instruments aboard the spacecraft are The Context Camera (CTX), Compact Reconnaissance Imaging Spectrometer for Mars (CHRISM), and Shallow Radar (SHARAD). These have contributed to many discoveries including Residual Slope Lineae (RSL) and dune movement measurements. In short, the HiRISE camera is essentially a telescope that points towards the ground. Its resolution has been compared to that of conventional Earth based satellite imagery, sometimes even better (although military satellites are another story). The camera is set up as a pushbroom, meaning, in a sense, it scans the surface as the instrument moves along its orbit. This is in contrast to frame cameras, which is similar to a photographers camera where an aperature is opened to accept light from the entire field of view all at once. The pushbroom style has a couple of advantages to it, including varying the length of images. The ability to toggle the length of the image is particularly helpful when scientists or citizens want to observe a really small or really long patch of the surface. The average HiRISE image is ~1-2 GB so being able to save memory space is crucial for smooth transmission back to Earth. Another useful aspect of the HiRISE camera is its color receiving CCDs. initially at the mission proposal, the scientists wanted full images in Red, Infrared, and Blue-Green bands. Due to weight and size constraints, the IR and BG bands had to be reduced in size from 10 CCDs to 2 each, placed in the middle. Since Mars emits most of its visible light in the Red band, it was kept at 10 CCDs. In 2011, the RED9 CCD died and so it no longer can process the light it receives. However the upshot is, of all the CCDs to kick the bucket, RED9 was probably the least problematic, tied with RED0, since it is on the very edge of the array. Below is an example how the CCDs are arranged.
HiRISE has been focused on geologic science for most of its life, but sometimes it takes a break to monitor other goings-on around it! In 2007, shortly after MRO entered its science orbit, the spacecraft rolled enough so that it could capture the Earth and Moon in this picture. There was also a fair amount of post processing to make it look as nice as it does.
In 2008, before the Phoenix Lander arrived at Mars, the mission planners of HiRISE knew where Phoenix would land and figured out what time the lander would be entering the Martian atmosphere. With careful calculation and planning, they where able to orient the spacecraft to point in the direction of the approaching lander and captured this incredible image!
And in 2014, Comet Siding Spring made a fairly close approach to the red planet and MRO was able to point toward the comet long enough to snap a picture, and then afterwards mission operators tried to keep the craft on the opposite side of the planet as much as they could, so the dust particles wouldn't damage the craft.
In 2015, while I worked as a student validator for HiRISE, a few images came through looking for the lost Beagle 2 mission that the UK launched in 2003. Scientists overlaid multiple images of the area in order to increase the resolution and eventually they were able to find it! The lander was lost soon after getting to the surface, and scientists now think it was because some of the solar panels were not fully deployed. Although I was among the first people to view the image, I was not able to identify where Beagle 2 was until the scientists overlaid the images.
All in all, HiRISE has been an amazing instrument for Mars and for us. The notion that I get to keep working with it fills me with happiness! Soon I may be applying this data to actual requesting of images so I can be on both sides of the equation for HiRISE!