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Phoenix (spacecraft)

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Phoenix is a robotic spacecraft on a space exploration mission to Mars under the Mars Scout Program. Notably it is the first scientist, or Principal Investigator (PI) led, mission to Mars. 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. Phoenix launched successfully on August 4 2007,[1] and is scheduled to land on Mars on May 25 2008. The multi-agency program is headed by the Lunar and Planetary Laboratory at the University of Arizona, under the direction of NASA. The program is a partnership of universities from the US, Canada, Switzerland, Denmark and Germany, NASA, the Canadian Space Agency, and the aerospace industry. Phoenix is planned to land in the planet's carbon ice-capped northern polar region and, if this is successful, will use its robotic arm to dig into the arctic terrain.[2]

History of the Phoenix Program

In August 2003 NASA selected the University of Arizona "Phoenix" mission for launch in 2007 as what is hoped will be the first in a new line of smaller, low-cost, Scout missions in the agency's exploration of Mars program.[3] 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. Like the mythic bird, the Phoenix spacecraft contains several previously built components. The lander used for the 2007 mission is the modified Mars Surveyor 2001 Lander (cancelled 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), Optech Incorporated, SETI Institute, Texas A&M University, Tufts University, University of Colorado, University of Michigan, University of Neuchâtel (Switzerland), University of Texas at Dallas, University of Washington, Washington University in St. Louis, and York University (Canada).

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.

The lander will land the same way the Viking program landers did, slowed primarily by landing rockets.[5] In 2007, a report was filed to the American Astronomical Society by Washington State University professor Dirk Schulze-Makuch, which made a claim that rocket exhaust contaminated the Viking landing sites, potentially killing any life that may have been there.[6] The hypothesis was made long after any modifications to Phoenix could be made without delaying the mission significantly. One of the investigators on the Phoenix mission, NASA astrobiologist Chris McKay, merely stated that the report "piqued his interest". 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.[7] Researchers at Tufts University, lead by Co-Investigator Sam Kounaves, will be conducting additional in depth experiments to identify the extent of the ammonia contamination and its possible effects on the chemistry experiments.

Phoenix launches atop a Delta II 7925 rocket

Launch

Phoenix launched on 4 August, 2007, at 5:26:34 a.m. EDT (09:26:34 BST) 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 11:30 a.m. PDT, was only 18 m/s. The launch took place during a launch window extending from 3 August 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 will launch 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]

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". The Phoenix's instruments are suitable for uncovering information on the geological and possibly biological history of the Martian Arctic. Because the Phoenix will be the first mission to return data from either of the poles, it will contribute to NASA's main strategy for Mars exploration, "Follow the water".

The primary mission is anticipated to last 90 Martian days (sols) — just over 92 Earth days.

Scientific payload

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 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.[9]

Robotic Arm

The Robotic Arm, (or RA for short) 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 carbon-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 in Pasadena California.

Robotic Arm Camera

The Robotic Arm Camera (RAC for short) 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 up. The camera was made by the University of Arizona and Max Planck Institute, Germany.

Surface Stereo Imager

The Surface Stereo Imager, or 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".[10] 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 and air and other features. The camera was provided by the University of Arizona in collaboration with the Max Planck Institute for Solar System Research.[11][12]

Thermal and Evolved Gas Analyzer

Thermal and Evolved Gas Analyzer, or 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 8 different ovens, each about the size of a large ball-point pen, which will be able to analyze one sample each, for a total of 8 different 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, up to 10 ppb. TEGA was built by the University of Arizona and University of Texas at Dallas.[13]

Mars Descent Imager

The Mars Descent Imager, or MARDI, will be used to take a picture of the Martian soil as the lander descends. As originally planned, it would have begun taking pictures after the aeroshell departed, about 5 miles above the Martian soil. Before launch, testing uncovered a potential data corruption problem with the hardware that handles multiple images. Since the same hardware handles information for other parts of the spacecraft, it was deemed an unacceptable risk to take multiple images. The flaw was discovered too late for repairs so mission planners decided to take just one photograph with MARDI.[14] Hopefully this one image can still help pinpoint exactly where the lander has landed, and possibly help find potential science targets. It will also 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.[15]

MARDI will be the lightest camera ever to land on Mars, as well as the most efficient. It only uses 3 watts of power during the imaging process, less than most other space cameras.

Microscopy, Electrochemistry, and Conductivity Analyzer

The Microscopy, Electrochemistry, and Conductivity Analyzer, or 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.[16] It was built by the Jet Propulsion Laboratory. The atomic force microscope is contributed by a Swiss [1] consortium led by the University of Neuchatel. The optical microscope is designed by the University of Arizona.

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.

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.

Meteorological Station

The Meteorological Station, or MET, will record the daily weather during the course of the Phoenix Mission. It is equipped with a variety of temperature and pressure sensors to do so. It is also equipped with LIDAR, or Laser Imaging Detection and Ranging, which will be used to find the amount and number of dust particles in the air. It was built by the Canadian Space Agency and a team headed by York University — and including contributions from the University of Alberta, Dalhousie University, Finnish Meteorological Institute[17], 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.[18]

The Phoenix DVD

Attached to the deck of the lander is "The Phoenix DVD" [2], compiled by the Planetary Society. The disc contains Visions of Mars [3], 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 the Fall of 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[19] designed to withstand the Martian environment, lasting for hundreds (if not thousands) of years on the surface while it awaits discoverers.

Engineering information

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.[20]

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 computer system for commanding the spacecraft and handling data.
  2. An electrical system containing solar arrays and batteries.
  3. A telecommunications system that can communicate directly with earth, as well as Mars Odyssey and the Mars Reconnaissance Orbiter.
  4. A sophisticated guidance system to ensure the spacecraft will land successfully.
  5. A propulsion system to land safely consisting of 6 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.
  • Conceptual image
    Conceptual image
  • On Launch Pad 17-A at Cape Canaveral Air Force Station, the Phoenix Mars Lander waits for the fairing installation. NASA/George Shelton
    On Launch Pad 17-A at Cape Canaveral Air Force Station, the Phoenix Mars Lander waits for the fairing installation. NASA/George Shelton
  • 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. (NASA)
    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. (NASA)

See also

References

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  1. ^ "NASA Phoenix Mission". NASA. Retrieved 2007-08-04.
  2. ^ Phoenix Mars Scout (wikisource)
  3. ^ "Mars 2007 'Phoenix' will Study Water near Mars' North Pole" August 4, 2003 NASA Press release. URL accessed April 2, 2006
  4. ^ "NASA's Phoenix Mars Mission Begins Launch Preparations". NASA. 2005-06-02. {{cite web}}: Unknown parameter |accesseddate= ignored (help)
  5. ^ "Phoenix Mars lander set to lift off". New Scientist. 2007-08-03. Retrieved 2007-08-04.
  6. ^ "Did probes find Martian life ... or kill it off?". Associated Press via MSNBC. 2007-01-08. Retrieved 2007-05-31. {{cite web}}: Unknown parameter |Author= ignored (|author= suggested) (help)
  7. ^ ""U-M scientists simulate the effects of blowing Mars dust on NASA's Phoenix lander, due for August launch"". University of Michigan News Service. 2007-06-07. {{cite web}}: Cite has empty unknown parameter: |1= (help); Unknown parameter |Author= ignored (|author= suggested) (help)
  8. ^ "Phoenix Mars Mission - Launch". University of Arizona. Retrieved 2007-08-06.
  9. ^ Shotwell R. (2005). "Phoenix — the first Mars Scout mission�". Acta Astronautica. 57: 121–134. doi:10.1016/j.actaastro.2005.03.038. {{cite journal}}: replacement character in |title= at position 39 (help)
  10. ^ "Phoenix Mars Lander- SSI". Phoenix Mars Lander. Retrieved 2006-04-02.
  11. ^ P. H. Smith, R. Reynolds, J. Weinberg, T. Friedman, M. T. Lemmon, R. Tanner, R. J. Reid, R. L. Marcialis, B. J. Bos, C. Oquest, H. U. Keller, W. J. Markiewicz, R. Kramm,F. Gliem and P. Rueffer (2001). "The MVACS Surface Stereo Imager on Mars Polar Lander" (PDF). Journal of Geophysical Research. 106 (E8): 17, 589–17, 607.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  12. ^ Reynolds R.O.,Smith P.H., Bell L.S., Keller, H.U. (2001). "The design of Mars lander cameras for Mars Pathfinder, MarsSurveyor '98 and Mars Surveyor '01". IEEE Transactions on Instrumentation and Measurement. 50 (1): 63–71. doi:10.1109/19.903879.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  13. ^ Boynton, W. V.; Quinn, R. C. (2005). "Thermal and Evolved Gas Analyzer: Part of the Mars Volatile and Climate Surveyor integrated payload". Journal of Geophysical Research. 106 (E8): 17683–17698. doi:10.1029/1999JE001153.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  14. ^ "One image planned during descent of Phoenix". The University of Arizona. July 3, 2007. {{cite web}}: Check date values in: |date= (help)
  15. ^ Malin, M. C.; Caplinger, M. A.; Carr, M. H.; Squyres, S.; Thomas, P.; Veverka, J. (2005). "Mars Descent Imager (MARDI) on the Mars Polar Lander" (PDF). 106: 17635–17650. doi:10.1029/1999JE001144. {{cite journal}}: Cite journal requires |journal= (help); Text "issue E8" ignored (help); Unknown parameter |Journal= ignored (|journal= suggested) (help)CS1 maint: multiple names: authors list (link)
  16. ^ "Spacecraft and Science Instruments". Phoenix Mars Lander. Retrieved 2007-03-10.
  17. ^ ""Phoenix probe takes FMI's pressure sensor to Mars" (In finnish)". Retrieved 2007-08-06.
  18. ^ "Mars robot with Canadian component set for Saturday launch". Phoenix Mars Lander. Retrieved 2007-08-03.
  19. ^ "The Phoenix DVD". Projects: Messages from Earth. Retrieved 2007-08-06.
  20. ^ "Phoenix Mars Lander- Spacecraft". Phoenix Mars Lander. Retrieved 2006-06-09.
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