Beyond_Earth-_A_Chronicle_of_Deep_Space_Exploration_1958-2016.pdf

207

Mars Express and Beagle 2

Nation: European Space Agency (2)

Objective(s): Mars orbit, Mars landing

Spacecraft: Mars Express

Spacecraft Mass: 1,186 kg

Mission Design and Management: ESA

Launch Vehicle: Soyuz-FG + Fregat (no. E15000-005 + 14S44 no. 1005)

Launch Date and Time: 2 June 2003 / 17:45:26 UT

Launch Site: GIK-5 / Site 31/6

Scientific Instruments:

Mars Express:

• 1. visible and infrared mineralogical mapping spectrometer (OMEGA)
• 2. ultraviolet and infrared atmospheric spectrometer (SPICAM)
• 3. sub-surface sounding radar altimeter (MARSIS)
• 4. planetary fourier spectrometer (PFS)
• 5. analyzer of space plasmas and energetic atoms (ASPERA)
• 6. high resolution stereo camera (HRSC)
• 7. Mars Express lander communications (MELACOM)
• 8. Mars radio science experiment (MaRS)
• 9. camera (VMC)

Beagle 2:

• 1. gas analysis package
• 2. environmental sensors
• 3. 2 stereoscopic cameras
• 4. microscope
• 5. Mössbauer spectrometer
• 6. x-ray spectrometer
• 7. planetary underground tool (PLUTO)

Results: ESA's first planetary mission (although launched by the Russians) had two parts, an orbiter and a lander. The orbiter was designed to image the entire surface of Mars in high resolution, produce a map of the mineral composition of its surface, map the composition of its atmosphere, determine the structure of the sub-surface (to a depth of a few kilometers), and study the effects of the atmosphere on its surface as well as the interaction of the atmosphere with the solar wind. It carried a number of instruments that were originally on the ill-fated Russian Mars 8 probe; several other nations also contributed, including the U.S., Poland, Japan, and China. The 33.2-kilogram British Beagle 2 lander (its name, an allusion to the HMS Beagle that carried the young Charles Darwin (1809–1882) on his historic voyage) was designed to conduct exobiology research and geochemistry research on the Martian surface. Its scientific suite included a gas analysis package that used a set of 12 gas heating ovens to heat soil to study released gases. After launch, the Fregat stage ignited twice, first to Earth orbit and second (at 19:03 UT) to send the spacecraft into heliocentric orbit. About 6 hours prior to entry into Mars orbit, at 08:31 UT on 19 December 2003, Mars Express successfully released Beagle 2, and without any active means of propulsion on board, it began its passive journey to the surface of Mars, landing as expected by 03:14 UT on 25 December. The American 2001 Mars Odyssey was programmed to relay the first signals from Beagle but heard nothing. Mars Express meanwhile fired its main engine at 02:47 UT on Christmas Day and entered an initial Mars orbit of 260 × 187,500 kilometers (with a period of 10 days), ESA thus achieving what had only been accomplished before by the United States and Soviet Union. After about a hundred days, in early May, the orbiter was in a 10,107 × 298-kilometer orbit with an orbital period of 6.7 hours. Attempts to contact Beagle 2 proved unsuccessful and the lander aspect of the mission was declared officially lost on 6 February 2004. In January 2015, ESA announced that high-resolution images taken by NASA's Mars Reconnaissance Orbiter (MRO) showed Beagle 2's wreckage on the Martian surface. The pictures revealed the lander partially deployed on the surface, confirming that entry, descent, and the landing sequence had gone well. Further improvement of these images by University College, London in the spring of 2016 led researchers to conclude by October 2016 that Beagle 2 did indeed touch down softly on Mars and had possibly deployed three of its four solar panels. The malfunction that killed the mission more likely happened soon after landing rather than before. Undoubtedly, the lander's development program was mismanaged with fatal shortcomings including insufficient testing of key systems. Mars Express meanwhile began to return valuable data on the Red Planet. It deployed the first of its two 20-meter long radar booms for the MARSIS experiment about a year later, on 4 May 2005, the second one being deployed on 14 June. The two booms together created a 40-meter-long dipole antenna to operate the MARSIS experiment. The spacecraft returned spectacular images of the planet's terrain; during its first Martian year, it had mapped one-quarter of the surface at a resolution of 20 meters per pixel in color and more than half of the surface at 50 meters. Within its first five years in orbit, the spacecraft had discovered relatively recent evidence of volcanic and glacial processes and the presence of water ice below the surface. Mars Express mapped the various types of ice in the polar regions and determined the history of water abundance on Mars. One of its most striking discoveries has been to confirm the existence of Methane in the atmosphere (announced on 30 March 2004), a presence independently confirmed by ground observations, but later clarified by data from Curiosity. The mission of Mars Express was first extended to October 2007, and then again to May 2009, far exceeding its original 687-Earth day lifetime. A further five extensions have followed since then, with the most recent one extending the mission to 2016. During these extended missions, the spacecraft aided the operation of future Mars probes such as NASA's Phoenix lander (in 2008) and also collected data on Phobos. On 3 March 2010, for example, Mars Express passed by Phobos at a range of just 67 kilometers, the closest any spacecraft had ever come to it by that time. This distance was beaten on 29 December 2013, when the spacecraft approached within just 45 kilometers of the Martian moon. Earlier, in August 2011, the probe ran into problems with its onboard computer memory and entered "safe mode" twice in response to emergencies. Fortunately, by 24 November 2011, controllers were able to bring the spacecraft back to full operating capacity. By the time of the 10th anniversary of its launch, ESA was able to release a near-complete topographical map of Mars showing the mountains, craters, ancient river beds, and lava flows that mark the planet. A potentially dangerous event for Mars Express was the flyby of Comet C/2013 A1 (also known as Siding Spring) near Mars on 19 October 2014. Because the range of the comet was only 385,000 kilometers, there were concerns about the possibility of the comet's coma enveloping Mars and along with it, the operational spacecraft in the vicinity of Mars (including at that time, the American Mars Reconnaissance Orbiter, 2001 Mars Odyssey, MAVEN, the European Mars Express, and the Indian Mars Orbiter Mission). In February 2015, scientists announced, based on data from Mars Express and NASA's MRO, that Phlegra Montes, a complex network of hills, ridges, and basins spanning 1,400 kilometers might hide large quantities of water-ice, perhaps only 20 meters below the surface. During three years, the Mars Express team continued with an interesting media experiment using the simple low-resolution camera originally designed to image the lost Beagle 2 lander. After the search for Beagle 2 concluded in 2003, that camera was switched off, but in 2007, ESA switched it back on, this time entirely for education and outreach. Images from the so-called Mars Webcam has been used by the public in dozens of countries, as enthusiasts downloaded, shared, and processed images, originally posted on a Flickr page. By May 2016, some 19,000 images, some of them based on requests from schools and youth clubs, had been viewed over two million times. In October 2016, Mars Express helped in the collection and transfer of data for the ill-fated Schiaparelli EDM lander that set down upon Mars. In November 2014, funding for the Mars Express mission was extended for the sixth time, to December 2016, and it continues to operate at full strength in mid-2017.

208

Spirit

Nation: USA (81)

Objective(s): Mars surface exploration

Spacecraft: Mars Exploration Rover 2 (MER 2) [became MER-A]

Spacecraft Mass: 1,062 kg

Mission Design and Management: NASA / JPL

Launch Vehicle: Delta 7925-9.5 (no. D298)

Launch Date and Time: 10 June 2003 / 17:58:47 UT

Launch Site: Cape Canaveral Air Force Station / SLC-17A

Scientific Instruments:

• 1. Panoramic Mast Assembly
  • a. panoramic cameras (Pancam)
  • b. navigation cameras (Navcam)
  • c. miniature thermal emission spectrometer (Mini-TES)
• 2. Mössbauer spectrometer (MB)
• 3. alpha particle x-ray spectrometer (APXS)
• 4. magnets (to collect dust particles)
• 5. microscopic imager (MI)
• 6. rock abrasion tool (RAT)

Results: Spirit and Opportunity were two rovers that together represented the Mars Exploration Rover Mission (MER), itself part of NASA's Mars Exploration Program. The twin missions' main scientific objective was to search for a range of rocks and soil types and then look for clues for past water activity on Mars. Each rover, about the size of a golf cart and seven times heavier (185 kilograms) than the Sojourner rover on Mars Pathfinder, was targeted to opposite sides of the planet in locales that were suspected of having been affected by liquid water in the past. The plan was for the rovers to move from place to place and perform on-site geological investigations and take photographs with mast-mounted cameras (about 1.5 meters off the ground) providing 360° stereoscopic views of the terrain. A suite of instruments (MB, APXS, the magnets, MI, and RAT) were deployed on a robotic arm (known as the Instrument Deployment Device, IDD). The arm would place the instruments directly against soil or rock and activate the instruments.

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The complete spacecraft was launched into an intermediate parking orbit around Earth of 163 × 4,762 kilometers at 28.5° inclination before the PAM-D upper stage fired to send it on to heliocentric orbit on a trajectory to intercept Mars. A mid-course correction followed 10 days later. After three more corrections, the spacecraft's "Cruise Stage" carrying the Spirit rover approached Mars for the landing on 4 January 2004. About 15 minutes prior to entry into the atmosphere, the lander (inside its protective aeroshell) separated from the Cruise Stage. At an altitude of 6 to 7.5 kilometers, a parachute deployed, followed 30 seconds later by release of the aeroshell's bottom heat shield. Within another 10 seconds, the rover unreeled down a "bridle" (or tether) while still descending at a rate of 70 meters/second. Four massive airbags, of the same type as the ones used on Mars Pathfinder, inflated soon after, followed by firing of the retrorockets at the base of the parachute until the lander was about 8.5 meters off the ground. The retrorockets were needed since the Martian atmosphere is less than 1% the density of Earth, and parachutes alone cannot reduce velocity. The entire package hit the Martian landscape at 04:26 UT at a velocity of 14 meters/second, bouncing a total of 28 times before rolling to a stop about 250–300 meters from point of first impact. Landing coordinates were 14.5692° S / 175.4729° E, about 13.4 kilometers from the planned target, inside the Gusev crater. The area was henceforth known as the Columbia Memorial Station. Through it all, the lander transmitted data via Mars Global Surveyor. About an hour-and-a-half after impact and after deflation of the airbags, MER-A deployed its petal solar panels, now relaying information to Earth via 2001 Mars Odyssey. Immediately after, Spirit began to transmit spectacular images back to Earth. The rover ran into a major problem on 21 January 2004 when NASA's Deep Space Network lost contact. Due to a problem in Spirit's flash memory subsystem, the rover entered a "fault mode." Fortunately, controllers were able to reformat the flash memory and send up a software patch (to preclude memory overload). Normal operations resumed again on 5 February and the day after, Spirit used its Rock Abrasion Tool (RAT) to ground down the surface of a rock (called "Adirondack"), a feat performed for the very first time on Mars. Investigating the exposed interior allowed scientists important insights into the composition of Martian soil. The original planned mission was to have lasted 90 Martian days (to approximately 4 April 2004). Yet, mission planners were able to repeatedly formulate extended missions well beyond the rover's original lifetime. Some of the subsequent highlights included a visit to Bonneville Crater, about 370 meters from its original landing point, then on to the base of Columbia Hills where it spent an extended period of time. By 2005, the rover began slowly making its way uphill to the apex of Husband Hill, over terrain that was both rocky and sandy. It stopped at many locations to investigate, often using the RAT. In March 2005, a peculiar and strange event, the passing of dust devils that swept dust from the top of the solar panels, increased power coming to Spirit from the usual 60% to 93%, thus significantly extending the lifetime of the mission. On 29 September 2005, the rover finally reached the summit of Husband Hill, a small flat plain, from which Spirit was able to take 360° panoramas in real color of the Gusev Crater. Early the following year, the rover was directed to the north face of McCool Hill where it was assumed that Spirit would receive sufficient sunlight to maintain operations through the impending Martian winter. The trip to McCool Hill was eventually canceled partly because a front wheel had stopped working. This malfunction proved to be beneficial since the inactive wheel scraped off the upper layer of Martian soil as the rover moved, exposing bright silica-rich dust that indicated contact between soil and water. In early 2007, controllers passed on new software to both Spirit and Opportunity. These new programs allowed the rovers to autonomously decide on a number of different actions, such as whether to transmit a particular image back to Earth or whether to extend the remote arm. Through much of the (Earth) summer of 2007, however, both Spirit and Opportunity faced massive dust storms that eroded their ability to operate effectively, mainly due to lack of power generated from the solar panels. These concerns did not abate into 2008 as another winter storm at the end of that year further reduced the output of Spirit's solar panel to about 89 watt-hours per Martian day (where a nominal amount would be about 700 watt-hours per day). At such low levels, the rover needed to resort to using its own batteries which, if ran dry, would basically end the mission. Through 2009, a series of fortuitous events—such as wind that blew dust off the panels—slowly increased power generated by the solar panels. By April 2009, the rover was back to about 372 watt-hours per day, sufficient for "normal" science activities to resume. Unfortunately, soon after, on 1 May 2009, while driving south beside the western edge of a low plateau called Home Plate, Spirit was rendered immobile in soft soil, its wheels unable to generate traction against the ground. Subsequently, on 28 November, another of Spirit's six wheels, the right rear one, stopped working. By late January 2010, after many attempts to move Spirit had not bore fruit, mission planners reformulated the Spirit mission as a "stationary science platform." One of its goals would now be to study the tiny wobbles in Mars' rotation to determine the nature of the planet's core—whether it is liquid or solid. In order to do that, however, the rover had to be tilted slightly to the north to expose its panels to the Sun, since the winter sun would be in the northern sky. In the end, the desired tilt was not achieved, and after 22 March 2010, JPL was not able to regain contact with Spirit again. Despite more than 1,300 commands sent to Spirit, NASA officially concluded its recovery efforts on 25 May 2011. The most probable cause of the loss of contact was the excessive cold that made its survival heaters ineffective. By the time it stopped, Spirit had traveled 7.73 kilometers across the Martian plains. It had operated for 6 years, 2 months, and 19 days, more than 25 times its original intended lifetime.