HiRISE
From Wikipedia, the free encyclopedia
The High Resolution Imaging Science Experiment camera is a camera on board the Mars Reconnaissance Orbiter. The 65 kg, $40 million (USD) instrument was built under the direction of the University of Arizona's Lunar and Planetary Laboratory by Ball Aerospace & Technologies Corp.. It consists of a 0.5 meter reflecting telescope, the largest of any deep space mission, which allows it to take pictures with resolutions up to 0.3 m, resolving objects about a meter across, or the size of a beachball.
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[edit] History
In the late 1980s, Alan Delamere of Ball Aerospace began planning the kind of high-resolution imaging needed to support sample return and surface exploration of Mars. In early 2001 he teamed up with Alfred McEwen of the University of Arizona to propose such a camera for MRO, and NASA formally accepted it November 9, 2001.[1]
Ball Aerospace was given the responsibility to build the camera and they delivered HiRISE to NASA on December 6, 2004, for integration with the rest of the spacecraft.[2] It was prepared for launch on board the MRO on August 12, 2005, to the cheers of the HiRISE team who were present. [3]
During the cruise phase of MRO, HiRISE took several calibration shots including several of the Moon and the Jewel Box cluster. These images helped to calibrate the camera and prepare it for taking pictures of Mars.
On March 10, 2006, MRO achieved Martian orbit and primed HiRISE to acquire some initial images of Mars.[4] The instrument had two opportunities to take pictures of Mars (the first was on March 24, 2006) before MRO entered aerobraking, during which time the camera was turned off for six months.[5] It was turned on successfully September 27, and took its first high-resolution pictures of Mars September 29.
On October 6, 2006 HiRISE took the first image of Victoria Crater, a site which is also under study by the rover Opportunity.[6]
In February 2007 seven detectors showed signs of degradation, with one IR channel almost completely degraded, and one other showing advanced signs of degradation. The problems appear to disappear when higher temperatures are used to take pictures with the camera.[7] As of March the degradation appeared to have stabilized, but the underlying cause remained unknown.[8]
On May 25, 2008, HiRISE imaged NASA's Mars Phoenix Lander parachuting down to Mars. It was the first time that a spacecraft imaged the final descent of another spacecraft onto a planetary body.[9]
[edit] Purpose
The HiRISE camera is designed to view surface features of Mars in greater detail than has previously been possible.[10] This allows for the study of the age of Martian features, looking for landing sites for future Mars landers, and in general, seeing the Martian surface in far greater detail than has previously been done from orbit. By doing so, it is allowing better studies of Martian channels and valleys, volcanic landforms, possible former lakes and oceans, and other surface landforms as they exist on the Martian surface.[11]
The general public will soon be allowed to request sites for the HiRISE camera to capture. For this reason, and due to the unprecedented access of pictures to the general public, shortly after they have been received and processed, the camera has been given the philosophy, "The People's Camera".[12]
[edit] Design
HiRISE was designed to be a High Resolution camera from the beginning. It consists of a large mirror, as well as a large CCD camera. Because of this, it achieves a resolution of 1 microradian, or 0.3 meter at a height of 300 km. (For comparison purposes, satellite images on Google Maps are available to 1 meter.[13]) It can image in three color bands, 400–600 nm (blue-green or B-G), 550–850 nm (red) and 800–1,000 nm (near infrared or NIR).[14]
Red color images are at 20,264 pixels wide (6 km in a 300 km orbit), and Green-Blue and NIR are at 4,048 pixels wide (1.2 km). HiRISE's onboard computer reads out these lines in time with the orbiter's ground speed, meaning the images are potentially unlimited in height. Practically this is limited by the onboard computer's 28 Gb memory capacity. The nominal maximum resolution of red images is 20,000 × 40,000 pixels, or 800 megapixels and 4,000 × 40,000 pixels (160 megapixels) for the narrower images of the B-G and NIR bands. A single uncompressed image uses 16.4 Gb. However, these images are transmitted compressed, at a total size of 5 Gigabits. These images are released to the general public on the HiRISE website via a new format called JPEG 2000.[15][16]
To facilitate the mapping of potential landing sites, HiRISE can produce stereo pairs of images from which the topography can be measured to an accuracy of 0.25 meter.
[edit] Images naming conventions
HIRISE images are available to the public, so it can be useful to know how they are named. This is an excerpt from the official documentation:
Name: ppp_oooooo_tttt_ffff_c.IMG ppp = Mission Phase: INT = Integration and Testing CAL = Calibration Observations ATL = ATLO Observations KSC = Kennedy Space Center Observations SVT = Sequence Verification Test LAU = Launch CRU = Cruise Observations APR = Mars Approach Observations AEB = Aerobraking Phase TRA = Transition Phase PSP = Primary Science Orbit (nov 2006-nov 2008) REL = Relay phase E01 = 1st Extended Mission Phase if needed Exx = Additional extended Missions if needed oooooo = MRO orbit number tttt = Target code ffff Filter/CCD designation: RED0-RED9 - Red filter CCDs IR10-IR11 – Near-Infrared filter CCDs BG12-BG13 – Blue-Green filter CCDs c = Channel number of CCD (0 or 1)
The target code refers to the latitudinal position of the center of the planned observation relative to the start of orbit. The start of orbit is located at the equator on the descending side (night side) of the orbit. A target code of 0000 refers to the start of orbit. The target code increases in value along the orbit track ranging from 0000 to 3595. This convention allows the file name ordering to be time sequential. The first three digits refers to the number of whole degrees from the start of orbit, the fourth digit refers to the fractional degrees rounded to the nearest 0.5 degrees. Values greater that 3595 identify observations as off-Mars or special observations.
Examples of target code:
0000 – planned observation at the equator on descending side of orbit. 0900 – planned observation at the south pole. 1800 – planned observation at the equator on the ascending side (day side) of the orbit. 2700 – planned observation at the north pole.
Off-Mars and Special Observations Values:
4000 – Star Observation 4001 – Phobos Observation 4002 – Deimos Observation 4003 – Special Calibration Observation
[edit] Footnotes
- ^ UANews (2001-11-09). "UA-Led Team's Ultra-High Resolution Camera Selected for 2005 Launch to Mars". Press release. Retrieved on 2006-06-08.
- ^ UANews (2004-12-06). "Ultra-sharp, Mars-Bound HiRISE Camera Delivered". Press release. Retrieved on 2006-06-08.
- ^ UANews (2005-08-08). "UA Team Cheers Launch of Mars Reconnaissance Orbiter, HiRISE". Press release. Retrieved on 2006-06-08.
- ^ Mars Reconnaissance Orbiter Successfully Enters Orbit Around Mars!. NASA MRO website. Retrieved on 2006-06-08.
- ^ NASA (2006-03-24). "UA Team Cheers Launch of Mars Reconnaissance Orbiter, HiRISE". Press release. Retrieved on 2006-06-08.
- ^ HiRISE | Victoria Crater at Meridiani Planum (TRA_000873_1780)
- ^ NASA (2007-02-07). "Spacecraft Set to Reach Milestone, Reports Technical Glitches". Press release. Retrieved on 2007-03-06.
- ^ Shiga, David. "Ailing Mars camera is stable – for now", NewScientist.com news service, 16 March 2007. Retrieved on 2007-03-18.
- ^ Camera on Mars Orbiter Snaps Phoenix During Landing. JPL website. Retrieved on 2008-05-28.
- ^ Alan Delamere (2003). "MRO HiRISE: Instrument Development". . 6th International Mars Conference Retrieved on 2008-05-25.
- ^ Science Goals. Lunar and Planetary Laboratory, University of Arizona. Retrieved on June 7, 2006.
- ^ HiRISE. Lunar and Planetary Laboratory, University of Arizona. Retrieved on 19 March 2006.
- ^ "Google Earth FAQ" Google Earth Website.
- ^ MRO HiRISE Camera Specifications. HiRISE website. Retrieved on 2 January 2006.
- ^ HiRISE: Instrument Development (PDF). NASA Ames Research Center website. Retrieved on 7 February 2006.
- ^ Fact Sheet: HiRISE (PDF). National Air and Space Museum. Retrieved on 18 February 2006.
[edit] External links
- HiRISE official website
- HiBlog, the official HiRISE blog
- Help NASA categorize images taken by HiRISE
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