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A worker prepares HiRISE before it is shipped for attachment to the spacecraft


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 Arizonamarker'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.

History

Crop of first image of Mars from the HiRISE camera


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 the Mars Reconnaissance Orbiter (MRO), and NASA formally accepted it November 9, 2001.

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. It was prepared for launch on board the MRO on August 12, 2005, to the cheers of the HiRISE team who were present.

Artist's rendition of HiRISE at Mars


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. 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. It was turned on successfully September 27, and took its first high-resolution pictures of Mars on September 29.

On October 6, 2006 HiRISE took the first image of Victoria Cratermarker, a site which is also under study by the Opportunity rover.

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. As of March, the degradation appeared to have stabilized, but the underlying cause remained unknown. Subsequent experiments with the Engineering Model (EM) at Ball Aerospace provided definitive evidence for the cause: contamination in the analog-to-digital converters (ADCs) which results in flipping bits to create the apparent noise or bad data in the images, combined with design flaws leading to delivery of poor analog waveforms to the ADCs. Further work showed that the degradation can be reversed by heating the ADCs.

On 2007-10-03, HiRISE was turned toward Earth, and took a picture of it and the Moon. In a full-resolution color image, Earth was 90 pixels across and the Moon was 24 pixels across from a distance of 142 million km.

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.

Purpose



The HiRISE camera is designed to view surface features of Mars in greater detail than has previously been possible. 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.

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".

Design

Earth and Moon from Mars Reconnaissance Orbiter taken by HiRISE
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.) 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).

HiRISE incorporates a 0.5-meter primary mirror, the largest optical telescope ever sent beyond Earth's orbit. The mass of the instrument is 64.2 kg.

Red color images are at 20,048 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 size of red images (compressed to 8 bits per pixel) is about 20,000 × 126,000 pixels, or 2520 megapixels and 4,000 × 126,000 pixels (504 megapixels) for the narrower images of the B-G and NIR bands. A single uncompressed image uses up to 28 Gb. However, these images are transmitted compressed,with a typical max size of 11.2 Gigabits. These images are released to the general public on the HiRISE website via a new format called JPEG 2000.

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.

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 latitudinalposition of the center of the plannedobservation relative to the start of orbit.The start of orbit is located at the equatoron the descending side (night side) of theorbit. A target code of 0000 refers to thestart of orbit. The target code increases invalue along the orbit track ranging from 0000to 3595. This convention allows the file nameordering to be time sequential. The firstthree digits refers to the number of wholedegrees from the start of orbit, the fourthdigit refers to the fractional degrees roundedto the nearest 0.5 degrees. Values greaterthan 3595 identify observations as off-Mars orspecial 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


Footnotes

  1. HiRISE | Victoria Crater at Meridiani Planum (TRA_000873_1780)
  2. " Google Earth FAQ" Google Earth Website.
  3. Mission to Mars: the HiRISE camera on-board MRO, Focal plane arrays for space telescopes III, 27-28 August 2007, San Diego, California, USA


External links




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