MSL Picture of the Day: T-16 Days: Eyes on Mars: Mars Reconnaissance Orbiter

MSL Picture of the Day: T-16 Days: Eyes on Mars: Mars Reconnaissance Orbiter

A towering dust devil casts a serpentine shadow over the Martian surface in this stunning, late springtime image of Amazonis Planitia.

The Mars Reconnaissance Orbiter (MRO), modelled after the Mars Global Surveyor, has been 6 years cycling Mars. MRO was launched on August 12, 2005, and had its arrival on Mars, with its orbital insertion on March 10, 2006. At the time Mars Global Surveyor, Mars ExpressMars Odyssey, and two Mars Exploration Rovers Spirit and Opportunity were all operational on Mars. Since then Mars Global Surveyor and Spirit ceased operations. Still leaving 4 mars probes researching Mars at the time I am writing this.
While en route to Mars most of the scientific instruments and experiments were tested and calibrated. Only three trajectory correction manoeuvres were necessary, which saved 27 kg (60 pounds) fuel which would be usable during the extended mission of MRO at present still happening.

MRO is a big satellite, weighing 1,031 kilograms (2,270 lb) without its fuel. It is much bigger than the Mars Global Surveyor (4 times that volume) and also bigger than the Mars Odyssey (about1.5 times bigger). MRO is to conduct surveillance of Mars from orbit.

The primary mission of MRO was 2 years, and, as it is 20 July today (15 years after the Pathfinder landing), that makes that an ‘overrun’ of 4 years already. Not just the satellite bus (body) is big; also the high gain antenna (insert image) and the solar panels are a good size, providing the spacecraft with 2,000. watts of power. <instert image of antenna + solar panel>

The solar panels of MRO can move independently around two axes (up-down, or left-right rotation). Each solar panel measures 5.35 × 2.53 meter and has 9.5 m2 (102 ft2) covered with 3,744 individual photovoltaic cells. These solar cells are able to convert more than 26% of the sun’s energy directly into electricity and are connected together to produce a total output of 32 volts. At Mars, each of the panels produces more than 1,000 watts of power, as Mars is further from the Sun than Earth. As both solar panels would produce 50% more power if they were flying in Earth orbit

MRO has two nickel-hydrogen rechargeable batteries used to power the spacecraft when it is not facing the sun. Each battery has an energy storage capacity of 50 ampere-hours (180 kC). The full range of the batteries cannot be used due to voltage constraints on the spacecraft, but allows the operators to extend the battery life—a valuable capability, given that battery drain is one of the most common causes of long-term satellite failure. Planners anticipate that only 40% of the batteries’ capacities will be required during the lifetime of the spacecraft. 

The Telecom Subsystem on MRO is the best digital communication system sent into deep space so far and for the first time using capacity approaching turbo-codes. It consists of a very large (3 meter) antenna, which is used to transmit data through the Deep Space Network via X-band frequencies at 8 GHz, and it demonstrates the use of the Ka band at 32 GHz for higher data rates.
Maximum transmission speed from Mars is projected to be as high as 6 Mbit/s, a rate ten times higher than previous Mars orbiters. The spacecraft carries two 100-watt X-band amplifiers(one of which is a backup), one 35-watt Ka-band amplifier, and two Small Deep Space Transponders (SDSTs).
MRO carries also two smaller low-gain antennas which can transmit and receive from any direction. They are an important backup system to ensure that MRO can always be reached, even if its main antenna is pointed away from the Earth.

The mission of MRO is to reconnoitre Mars from orbit, hence its name.
The mission is managed by the Jet Propulsion Laboratory, at the California Institute of TechnologyLa Canada Flintridge, California

MRO was actually to launch 2 years earlier as it was one of two missions being considered for the 2003 Mars launch window. As we all know in 2003 the Mars Exploration Rovers were launched instead of this orbiter.

It took MRO 5 months of aerobraking to arrive in its proper orbit around Mars by dipping into the Martian atmosphere time and again. Aerobraking is a three-step procedure used because it halves the fuel needed to achieve a lower, more circular orbit with a shorter period..

* Starting the procedure on March 30, 2006, MRO began its aerobraking, by first firing its thrusters three times to drop the periapsis – the point in the orbit closest to Mars – of its orbit into aerobraking altitude. This altitude depends on the thickness of the atmosphere, because Martian atmospheric density changes with its seasons.

* Second, while using its thrusters to make minor corrections to its periapsis altitude, MRO maintained aerobraking altitude for 445 planetary orbits (about 5 Earth months) to reduce the apoapsis – the point in the orbit furthest from Mars – of the orbit to 450 kilometres (280 mi). This is a delecate process as one has to balance the manoeuvre to neither heat the spacecraft too much up by the friction with the atmosphere, nor dip too little into the atmosphere as then the spacecraft would not slow down fast enough.

* After the process was complete, MRO used its thrusters to move its periapsis out of the edge of the Martian atmosphere on August 30, 2006. By September 2006 MRO had arrived at a nearly circular orbit of 250 to 316 kilometres (160-196 miles) above the Martian surface.

From October 7 to November 6, 2006 a solar conjunction occurred, which means that our Sun is in direct line of sight with Mars, preventing us from communicating with our Mars probes. The primary science mission of MRO started on November 17, 2006, not long after this solar conjunction, by sending data from the mars rover “Spirit” via MRO acting as a relay back to Earth.

One of the very first images taken by the MRO is the image of Victoria crater along with the Opportunity rover on the rim above it.

Regrettably MRO started to have problems as early as November 2006, as two instruments acted up.

A stepping mechanism in the Mars Climate Sounder (MCS) skipped on multiple occasions resulting in a field of view that is slightly out of position. By December normal operations of the instrument was suspended, although a mitigation strategy allows the instrument to continue making most of its intended observations.

Several CCDs of the High Resolution Imaging Science Experiment (HiRISE) showed an increase in noise which results in bad pixels. To alleviate this issue the operating team allows the camera a longer warm-up time and HiRISE continues to return images which have enabled discoveries regarding the geology of Mars. The cause of its malfunction is still unknown.

The orbiter continued to experience recurring problems in 2009, including four spontaneous resets, culminating in a four-month shut-down of the space craft from August to December 2009. While engineers have not determined the cause of the recurrent resets, they have created new software to help troubleshoot the problem should it recur. At the moment a reaction wheel of MRO has shut down. This may mean that MRO will not be overhead while Curiosity is landing.

MRO has four or such reaction wheels used for precise attitude control during activities requiring a highly stable platform, such as high-resolution imaging, in which even small motions can cause blurring of the image. Each wheel is used for one axis of motion. The fourth (skewed) wheel is a backup in case one of the other three wheels fails. Each wheel weighs 10 kg (22 lb) and can be spun as fast as 100 Hz or 6,000 rpm.

MRO has the following Instruments:

High Resolution Imaging Science Experiment (HiRISE), a 0.5 m reflecting telescope, the largest every carried on a deep space mission. This visible camera can reveal small-scale objects as it has a resolution of 1 microradian (μrad), or 0.3 meter (1 foot) from an altitude of 300 km. Satellite images of Earth are generally available with a resolution of 0.5 meter (1.5 feet) and satellite images on Google Maps are available to 1 meter (over 3 feet). HiRISE collects images in three color bands, 400 to 600 nm (blue-green or B-G), 550 to 850 nm (red) and 800 to 1,000 nm (near infrared or NIR). 

Each 16.4 Gb image is compressed to 5 Gb before transmission and release to the general public on the HiRISE website in JPEG 2000 format. To facilitate the mapping of potential landing sites, HiRISE can produce stereo pairs of images from which topography can be calculated to an accuracy of 0.25 meter (less than 1 foot)
HiRISE was able to photograph the Phoenix Lander during its parachuted descent to Vastitas Borealis on May 25, 2008.

The Context Camera (CTX), operated by Malin Space Science Systems as so many cameras on Mars, provides wide area views to help provide a context for high-resolution analysis of key spots on Mars provided by HiRISE and CRISM. CTX provides grayscale images (500 to 800 nm) with a pixel resolution up to about 6 meter (20 feet). CTS is also used to mosaic large areas of Mars. In the hope of spotting changes over time CTX is monitoring a number of locations. CTX mapped 50% of Mars by February 2010.
The optics of CTX consist of a 350 mm focal length Maksutov Cassegrain telescope with a 5,064 pixel wide line array CCD. The instrument takes pictures 30 km (19 mi) wide and has enough internal memory to store an image 160 km long before loading it into the main computer. 

The Mars Color Imager (MARCI), also operated by Malin Space Science Systems, acquires a global view of the red planet and its weather patterns every day looking for clouds and duststorms.
MARCI is a wide-angle, relatively low-resolution camera with a 180 degree fisheye lens with the seven color filters bonded directly a single CCD sensor, that views the surface of Mars in five visible and two ultraviolet bands. Each day, MARCI collects about 84 images and produces a global map with pixel resolutions of 1 to 10 km. This map provides a daily weather report for Mars, At the MSSS site can one see the weather report on Mars for the last week. MARCI maps the presence of water vapor and ozone in its atmosphere.

The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument splits visible and near-infrared light of its images into hundreds of “colors” that identify minerals, especially those likely formed in the presence of water, in surface areas on Mars not much bigger than a football field. CRISM is looking for materials like iron, oxidesphyllosilicates, and carbonates.

The Mars Climate Sounder (MCS) is an atmospheric profiler set up to detect vertical variations of temperature, dust, and water vapor concentrations in the Martian atmosphere. MCS is also a spectrometer with just one visible/near infrared channel (0.3 to 3.0 μm) and eight far infrared (12 to 50 μm) channels.
These channels were selected to measure temperature, pressure, water vapor and dust levels. 
MCS observes the atmosphere on the horizon of Mars (as viewed from MRO) by breaking it up into vertical slices and taking measurements within each slice in 5 km (3 mi) increments. These measurements are assembled into daily global weather maps to show the basic variables of Martian weather: temperature, pressure, humidity and dust density.

MRO’s Shallow Subsurface Radar (SHARAD) is a sounding radar probing beneath the Martian surface to see if water ice is present at depths greater than one meter.
Note: Mars Odyssey could only look into the Mars subsurface up to 1 meter depth.

SHARAD is probing the internal structure of the Martian polar ice caps. But SHARAD is not only looking at the polar caps of Mars, as It also gathers planet-wide information about underground layers of icerock and possibly liquid water that might be accessible from the surface.

SHARAD uses HF radio waves between 15 and 25 MHz, a range that allows it to resolve layers as thin as 7 m (23 ft) to a maximum depth of 1 km (0.6 mi). It has a horizontal resolution of 0.3 to 3 km (0.2 to 1.9 mi).

SHARAD works together with the Mars Express MARSIS, which has lower resolution but penetrates to a much greater depth. Both SHARAD and MARSIS were made by the Italian Space Agency.

Between January and September 2008 a meteorite hit the surface of Mars, exposing subsurface water ice.

A dust storm moves over Icaria Planum.

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