Phoenix (spacecraft)

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Phoenix Mars Mission
Artist's impression of the Phoenix spacecraft as it lands on Mars
Organization	NASA
Major contractors	Lockheed Martin
Mission type	Lander
Decay	May 25, 2008 (2008-05-25); 2 days ago (soft landing on Mars)
Launch date	August 4, 2007
Launch vehicle	Delta II 7925
Mission duration	90 sols, 92.46 days
NSSDC ID	2007-034A
Webpage	http://phoenix.lpl.arizona.edu/

Phoenix is a robotic spacecraft on a space exploration mission on Mars under the Mars Scout Program. The scientists conducting the mission will use instruments aboard the Phoenix lander to search for environments suitable for microbial life on Mars, and to research the history of water there. The multi-agency program is headed by the Lunar and Planetary Laboratory at the University of Arizona, under the direction of NASA's Jet Propulsion Laboratory. The program is a partnership of universities in the United States, Canada, Switzerland, the Philippines, Denmark, Germany and the United Kingdom, NASA, the Canadian Space Agency, the Finnish Meteorological Institute, Lockheed Martin Space Systems, and other aerospace companies.^[1]

Phoenix is the sixth successful landing on Mars, out of twelve total international attempts (the sixth successful landing of seven American attempts). It is the third successful static lander since Viking 2, and as of 2008 the most recent spacecraft to land successfully on Mars.

[edit] History of the program

Artist's depiction of Phoenix using a robotic arm to dig down to the expected icy layer

In August 2003 NASA selected the University of Arizona "Phoenix" mission for launch in 2007 as what was hoped would be the first in a new line of smaller, low-cost, Scout missions in the agency's exploration of Mars program.^[2] The selection was the result of an intense two-year competition with proposals from other institutions. The $325 million NASA award is more than six times larger than any other single research grant in University of Arizona history.

Peter H. Smith of the University of Arizona Lunar and Planetary Laboratory, as Principal Investigator, along with 24 Co-Investigators, were selected to lead the mission. The mission was named after the Phoenix, a mythological bird that is repeatedly reborn from its own ashes. The Phoenix spacecraft contains several previously built components. The lander used for the 2007-08 mission is the modified Mars Surveyor 2001 Lander (canceled in 2000), along with several of the instruments from both that and the previous unsuccessful Mars Polar Lander mission. Lockheed Martin had kept the nearly complete lander in environmentally controlled storage since 2001.

Phoenix during testing in September 2006

Phoenix is a partnership of universities, NASA centers, and the aerospace industry. The science instruments and operations will be a University of Arizona responsibility. NASA's Jet Propulsion Laboratory in Pasadena, California, will manage the project and provide mission design and control. Lockheed Martin Space Systems, Denver, Colorado, built and tested the spacecraft. The Canadian Space Agency will provide a meteorological station, including an innovative Laser-based atmospheric sensor. The co-investigator institutions include Malin Space Science Systems (California), Max Planck Institute for Solar System Research (Germany), NASA Ames Research Center (California), NASA Johnson Space Center (Texas), De La Salle University (Philippines), Optech Incorporated, SETI Institute, Texas A&M University, Tufts University, University of Colorado, University of Copenhagen (Denmark), University of Michigan, University of Neuchâtel (Switzerland), University of Texas at Dallas, University of Washington, Washington University in St. Louis, and York University (Canada). Scientists from Imperial College London and Bristol University have provided hardware for the mission and will be part of the team operating the microscope station.^[3]

On June 2, 2005, following a critical review of the project's planning progress and preliminary design, NASA approved the mission to proceed as planned.^[4] The purpose of the review was to confirm NASA's confidence in the mission.

Phoenix landed the same way as the Viking program spacecraft, slowed primarily by rockets.^[5] Experiments conducted by Nilton Renno, mission Co-Investigator from the University of Michigan, and his students have specifically looked at how much surface dust will be kicked up when Phoenix lands.^[6] Researchers at Tufts University, led by Co-Investigator Sam Kounaves, will be conducting additional in depth experiments to identify the extent of the ammonia contamination from the hydrazine propellent and its possible effects on the chemistry experiments. In 2007, a report was filed to the American Astronomical Society by Washington State University professor Dirk Schulze-Makuch, suggesting that Mars might harbor peroxide-based life forms which the Viking landers failed to detect because of the unexpected chemistry.^[7] The hypothesis was proposed long after any modifications to Phoenix could be made. One of the Phoenix mission investigators, NASA astrobiologist Chris McKay, stated that the report "piqued his interest" and that ways to test the hypothesis with Phoenix's instruments would be sought.

[edit] Launch

Phoenix is launched atop a Delta II 7925 rocket

Phoenix was launched on 4 August 2007, at 5:26:34 am EDT (09:26:34 UTC) on a Delta 7925 launch vehicle from Pad 17-A of the Cape Canaveral Air Force Station. The launch was nominal with no significant anomalies. Mars Phoenix Lander was placed on a trajectory of such precision that its first trajectory course correction burn, performed on 10 August 2007 at 7:30 a.m. EDT (11:30 UTC), was only 18 m/s. The launch took place during a launch window extending from 3 August 2007 to 24 August 2007. Due to the small launch window the rescheduled launch of the Dawn mission (originally planned for 7 July) had to stand down and was launched after Phoenix in September. The Delta 7925 was chosen due to its successful launch history, which includes launches of the Spirit and Opportunity Mars Exploration Rovers in 2003 and Mars Pathfinder in 1996.^[8]

[edit] Mission profile

The mission has two goals. One is to study the geologic history of water, the key to unlocking the story of past climate change. The second is to search for evidence of a habitable zone that may exist in the ice-soil boundary, the "biological paydirt." Phoenix's instruments are suitable for uncovering information on the geological and possibly biological history of the Martian Arctic. Phoenix will be the first mission to return data from either of the poles, and will contribute to NASA's main strategy for Mars exploration, "Follow the water."

The primary mission is anticipated to last 90 sols (Martian days) – just over 92 Earth days. Researchers are hoping that the lander will survive into the Martian winter so that it can witness polar ice developing at the spacecraft's exploration area. As much as three feet of solid carbon dioxide ice could appear in the area. Even if it does survive partway into the winter, it is very unlikely that the lander will function throughout the entire winter due to the intense cold.^[9] The mission was chosen to be a fixed lander rather than a rover because:^[10]

1. costs were reduced through reuse of earlier equipment;
2. the area of Mars where Phoenix is landing is thought to be relatively uniform and thus traveling is of less value; and
3. the equipment weight that would be required to allow Phoenix to travel can instead be dedicated to more and better scientific instruments.

Phoenix successfully landed in the Green Valley of Vastitas Borealis on May 25, 2008,^[11] in the late Martian northern hemisphere spring (L_s = 76.73), where the Sun will shine on its solar panels the whole martian day.^[12] By the martian northern Summer solstice (2008-06-25), the Sun will appear at its maximum elevation of 47.0 degrees. Phoenix will experience its first sunset at the start of September 2008.^[12]

[edit] Landing

Cryoturbation polygons due to the Martian permafrost

Preparations were made to arrange for three Mars orbiting satellites to be in the right place on May 25, 2008, to observe Phoenix as it entered the atmosphere and to monitor it up to one minute after landing. This information will allow for better design for future landers.^[13] The projected landing area was an ellipse 100 km by 20 km covering terrain which has been informally named "Green Valley"^[14] and contains the largest concentration of water ice outside of the poles.

A camera on the Mars Reconnaissance Orbiter snaps Phoenix suspended from its parachute during descent through the Martian atmosphere.

A camera on the Mars Reconnaissance Orbiter snaps Phoenix on the surface of Mars. It is the blue "butterfly" in the center.

Phoenix entered the Martian atmosphere at nearly 21,000 km per hour, and within 7 minutes had to be able to decrease its speed to 8 km an hour before touching down on the surface. Confirmation of atmospheric entry was received at 4:46 p.m. PDT (23:46 UTC). Radio signals received at 4:53:44 p.m. PDT confirmed that Phoenix had survived its difficult descent and landed 15 minutes earlier, thus completing a 680 million kilometer flight from Earth.^[15]

Parachute deployment was about 7 seconds later than expected, leading to a landing position some 25–28 km long (east), near the edge of the predicted 99% landing ellipse. The reason for this delay is not yet known. The landing position is still uncertain, with a 99% confidence radius of about 10 km around an estimated position of 68.25°N, 234.3°E.^[16]

Phoenix was imaged by Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE) camera while suspended from its parachute during the lander's successful arrival at Mars. This marks the first time ever one spacecraft has photographed another in the act of landing on a planet^[15][17] (the Moon not being a planet, but a satellite). The same camera also imaged Phoenix on the surface with enough resolution to distinguish the lander and its two solar cell arrays.

The landing was made on a flat surface, with the lander reporting only 0.3 degrees of tilt. Just prior to landing, the craft performed a successful reorientation using its thrusters to allow the solar panels to deploy along an east-west axis to maximize power generation. The lander waited 10 minutes before opening its solar panels, to allow dust to settle. The first images from the lander became available around 7:00 p.m. PDT (2008-05-26 02:00 UTC).^[18] The images show a surface strewn with pebbles and incised with small troughs into polygons about 5 m across and 10 cm high, with the expected absence of large rocks and hills.

The polygonal cracking in this area had previously been observed from orbit, and is similar to patterns seen in permafrost areas in polar and high altitude regions of Earth. A likely formation mechanism is that permafrost ice contracts when the temperature decreases, creating a polygonal pattern of cracks, which are then filled by loose soil falling in from above. When the temperature increases and the ice expands back to its former volume, it thus cannot assume its former shape, but is forced to buckle upwards.^[19] (On Earth, liquid water would probably enter at times along with soil, creating additional disruption due to ice wedging when the contents of the cracks freeze.)

Phoenix footpad image, taken over 15 minutes after landing to ensure any dust stirred up had settled.

One of the first surface images from Phoenix.

Flat terrain with a polygonal pattern stretches from the foreground to the horizon.

Comparison between polygons photographed by Phoenix on Mars...

... and as photographed (in false color) from Mars orbit...

... with patterned ground on Devon Island in the Canadian Arctic.

[edit] Scientific payload

MVACS is an integrated payload with four major science elements: a Stereo Surface Imager, a Robotic Arm with Camera, a Meteorological package of pressure, temperature, wind, and water vapor sensors, and a Thermal and Evolved Gas Analyzer.

Phoenix carries improved versions of University of Arizona panoramic cameras and volatiles-analysis instrument from the ill-fated Mars Polar Lander, as well as experiments that had been built for the canceled Mars Surveyor 2001 Lander, including a JPL trench-digging robot arm, a set of wet chemistry laboratories, and optical and atomic force microscopes. The science payload also includes a descent imager and a suite of meteorological instruments.^[20]

[edit] Robotic Arm and Camera

The Robotic Arm (RA) is designed to extend 2.35 m from its base on the lander, and have the ability to dig down to half a meter below the surface. It will take samples of dirt and water-ice that will be analyzed by other instruments on the lander. The arm was designed and built for the Jet Propulsion Laboratory by Alliance Spacesystems, LLC^[21] in Pasadena, California.

The Robotic Arm Camera (RAC) attached to the Robotic Arm just above the scoop is able to take full-color pictures of the area, as well as verify the samples that the scoop will return, and examine the grains of the area where the Robotic Arm has just dug. The camera was made by the University of Arizona and Max Planck Institute for Solar System Research,^[22] Germany.^[23]

[edit] Surface Stereo Imager

Surface Stereo Imager (SSI) built by the University of Arizona.

The Surface Stereo Imager (SSI) is the primary camera on the spacecraft. It is a stereo camera that is described as "a higher resolution upgrade of the imager used for Mars Pathfinder and the Mars Polar Lander".^[24] It is expected to take many stereo images of the Martian Arctic. It will also be able, using the Sun as a reference, to measure the atmospheric distortion of the Martian atmosphere due to dust, air and other features. The camera was provided by the University of Arizona in collaboration with the Max Planck Institute for Solar System Research.^[25][26]

[edit] Thermal and Evolved Gas Analyzer

Thermal and Evolved Gas Analyzer (TEGA).

The Thermal and Evolved Gas Analyzer (TEGA) is a combination of a high-temperature furnace with a mass spectrometer. It will be used to bake samples of Martian dust, and determine the content of this dust. It has eight ovens, each about the size of a large ball-point pen, which will be able to analyze one sample each, for a total of eight separate samples. Team members can measure how much water vapor and carbon dioxide gas are given off, how much water-ice the samples contain, and what minerals are present that may have formed during a wetter, warmer past climate. The instrument will also be capable of measuring any organic volatiles, down to 10 ppb. TEGA was built by the University of Arizona and University of Texas at Dallas.^[27]

[edit] Mars Descent Imager

Mars Descent Imager built by Malin Space Science Systems.

The Mars Descent Imager ("MARDI") was intended to take pictures of the landing site during the last three minutes of descent. As originally planned, it would have begun taking pictures after the aeroshell departed, about 8 km above the Martian soil.

Before launch, testing of the assembled spacecraft uncovered a potential data corruption problem with an interface card that was designed to route MARDI image data as well as data from various other parts of the spacecraft. The potential problem could occur if the interface card were to receive a MARDI picture during a critical phase of the spacecraft's final descent, at which point data from the spacecraft's Inertial Measurement Unit could have been lost; this data was critical to controlling the descent and landing. This was judged to be an unacceptable risk, and it was decided to not use MARDI during the mission.^[28] As the flaw was discovered too late for repairs, the camera remains installed on Phoenix; it was not used to take pictures, nor was its built-in microphone used.^[29]

After launch, an alternative plan was developed for MARDI to capture a single image during descent; but it was determined that this would have required changes to the timing of events during descent, so the alternative plan was also discarded, in favor of reducing risk.

MARDI images had been intended to help pinpoint exactly where the lander has landed, and possibly help find potential science targets. It was also to be used to learn if the area where the lander lands is typical of the surrounding terrain. MARDI was built by Malin Space Science Systems.^[30]

MARDI is the lightest and most efficient camera ever to land on Mars. It would have used only 3 watts of power during the imaging process, less than most other space cameras. It had originally been designed and built to perform the same function on the Mars Surveyor 2001 Lander mission; after that mission was cancelled, MARDI spent several years in storage until it was deployed on the Phoenix lander.

[edit] Microscopy, Electrochemistry, and Conductivity Analyzer

A prototype wet chemistry beaker showing some of the electrochemistry sensors on the sides of the beaker.

The Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) is an instrument package (originally designed as such for the cancelled 2001 MSP mission) consisting of a wet chemistry lab (WCL), optical and atomic force microscope, and a thermal and electrical conductivity probe.^[31] It was built by the Jet Propulsion Laboratory. The atomic force microscope is contributed by a Swiss consortium led by the University of Neuchatel.^[32] The optical microscope is designed by the University of Arizona. The reagents and sensors were developed by Tufts University. [1], with the microscope sample substrates provided by Imperial College London.^[33]

Using this instrument, researchers will examine soil particles as small as 16 micrometres across. They will measure electrical and thermal conductivity of soil particles using a probe on the robotic arm scoop.^[34]

The robotic arm will scoop up some soil, put it in one of four wet chemistry lab cells, where water will be added, and while stirring, an array of electrochemical sensors will measure a dozen dissolved ions such as sodium, magnesium, calcium, and sulfate in the water, that have leached out from the soil. This will provide information on the biological compatibility of the soil, both for possible indigenous microbes and for possible future Earth visitors. Sensors will also measure the pH and conductivity of the soil-water mixture, telling if the wet soil is super acidic or alkaline and salty, or full of oxidants that can destroy life.^[35]

[edit] Meteorological Station

Meteorological Station (MET) built by the Canadian Space Agency.

Phoenix deployed and then imaged the MET weather mast that holds, at the top at 2.3 metres height, the wind-strength and direction-measuring telltale and one of three temperature sensors.Credit:NASA

The Meteorological Station (MET) will record the daily weather during the course of the Phoenix mission. It is equipped with a wind indicator and pressure and temperature sensors to do so. It is also equipped with lidar (laser imaging detection and ranging), which will be used to find the number of dust particles in the air. It was designed in Canada and supported by the Canadian Space Agency and a team headed by York University—and including contributions from the University of Alberta, University of Aarhus (Denmark)^[36], Dalhousie University,^[37] Finnish Meteorological Institute,^[38] Optech, and the Geological Survey of Canada—will oversee the science operations of the station, which was built by Canadarm maker MacDonald Dettwiler and Associates Ltd. of Richmond, B.C.^[39]

The lidar laser is a passive Q-switched Nd:YAG laser with the dual wavelengths of 1064 nm and 532 nm. It operates at 100 Hz with a pulse width of 10 ns. The lidar is vertically pointing. The scattered light is received by two detectors and operates in both analog and photon counting modes.^[40][41]

All types of backscattering (for example Rayleigh scattering and Mie Scattering) are the basic premise employed by the lidar. With the delay between laser pulse generation and light scattered by atmospheric particles determining the altitude at which scattering occurs. Additional information can be obtained from backscattered light at 532 nm and 1064 nm, and such wavelength dependence may make it possible to discriminate between ice and dust, and serve as an indicator of the effective particle size.

The lidar will get information about the time-dependent structure of the planetary boundary layer by investigating the vertical deistribution of dust, ice, fog and clouds in the local atmosphere. The surface wind velocity and temperatures will also be monitored over time and show the evolution of the atmosphere over time. Dust and ice contribution in the atmosphere and the formation of dust devils are in the science focus of the instrument.

[edit] The Phoenix DVD

Attached to the deck of the lander (next to the US Flag) is "The Phoenix DVD",^[42] compiled by the Planetary Society. The disc contains Visions of Mars,^[43] a multimedia collection of literature and art about the Red Planet. Works include the text of H.G. Wells' War of the Worlds (and its infamous radio broadcast by Orson Welles), Percival Lowell's Mars as the Abode of Life with a map of his proposed canals, Ray Bradbury's The Martian Chronicles, and Kim Stanley Robinson's Green Mars. There are also messages directly addressed to future Martian visitors or settlers from, among others, Carl Sagan and Arthur C. Clarke. In 2006, The Planetary Society collected a quarter million names submitted through the internet and placed them on the disc, which claims, on the front, to be "the first library on Mars".

The Phoenix DVD is made of a special silica glass^[42] designed to withstand the Martian environment, lasting for hundreds (if not thousands) of years on the surface while it awaits discoverers.

[edit] Engineering information

A labeled look at NASA's Mars Phoenix Lander.

The Phoenix Lander was built by Lockheed Martin. Most of its parts were built for the canceled Mars Surveyor 2001 Lander. It was then locked away in a clean room for several years, until the mission was funded by the NASA Scout Program.^[44]

While many of the parts are being used from the previous spacecraft, many others have been updated. The lander contains the following subsystems:

1. A RAD6000 based computer system for commanding the spacecraft and handling data.^[45]
2. An electrical system containing solar arrays and batteries.
3. A digital telecommunications system that can communicate directly with earth, as well as Mars Odyssey and the Mars Reconnaissance Orbiter, all now using for the first time turbo-codes for error correction. The interconnections use the Proximity-1 protocol.^[46]
4. A sophisticated guidance system to ensure the spacecraft will land successfully.
5. A propulsion system to land safely consisting of six hydrazine engines.
6. The structure of the spacecraft.
7. Several mechanical systems to move parts of the spacecraft.
8. A sophisticated thermo-control system to ensure the spacecraft does not get too cold.

The lander has a mass of 350 kg, and measures 2.2 meters tall by 5.5 meters long with its solar panels deployed. The science deck is about 1.5 meters in diameter.^[46]

[edit] Gallery

A photograph showing NASA engineers working on the Phoenix Mars Lander	A stitched photograph showing both the surface and horizon.	One of the first horizon images taken by Phoenix.
Conceptual image.	On Launch Pad 17-A at Cape Canaveral Air Force Station, the Phoenix Mars Lander waits for the fairing installation. Phoenix' sterilized heat shield is encapsulated in the white bio shield to prevent an infection of Earthly bacteria. The bio shield as well as surface bacteria are incinerated during the descent.	On Launch Pad 17-A at Cape Canaveral Air Force Station, the first half of the fairing is moved into place around the Phoenix Mars Lander for installation. The grey sphere is the PAM-D solid rocket that gave Phoenix the final velocity for the Martian cruise.
The noctilucent cloud[47] in this photograph was created by the exhaust gas from the Delta II 7925 rocket used to launch Phoenix.

[edit] See also

Mars Portal

Spaceflight Portal

• 2007 in spaceflight
• 2008 in spaceflight
• Exploration of Mars

[edit] References

[edit] External links

Wikimedia Commons has media related to:

Phoenix mission

Wikinews has related news:

• Phoenix spacecraft launches towards Mars
• Canada contributes weather station to NASA Mars mission
• NASA's Phoenix spacecraft lands safely on Mars

• Mars Phoenix Twitter Page

[edit] LPL, LMSS, JPL and NASA links

• Phoenix mission lead home page
• Phoenix summary at JPL
• Phoenix Profile by NASA's Solar System Exploration
• NASA's Phoenix Photojournal
• NASA Archives of raw Phoenix mission images, most recent first
• NASA TV broadcast of Phoenix landing (YouTube copy of NASA broadcast from 8 minutes before until 2 minutes after touchdown)

[edit] Other links

• Phoenix status at Space Flight Now
• Complete List of Works on the Phoenix DVD
• Written Introduction to the Visions of Mars Project
• Phoenix Mission Details Video
• may 2008-2.html Mars Express Support to Phoenix Landing Includes animation of Phoenix descent and landing, plus KSC images of pre-flight processing and launch
• Live Simulcast of Landing in Second Life to take place at Spectre Island Science Museum
• Article and news footage on the Phoenix landing
• Unmanned Spaceflight.com > Phoenix 2007/8 active discussion forum
• Canadian contribution at the University of Alberta

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