Beyond_Earth-_A_Chronicle_of_Deep_Space_Exploration_1958-2016.pdf

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Mars Reconnaissance Orbiter

Nation: USA (86)

Objective(s): Mars orbit

Spacecraft: MRO

Spacecraft Mass: 2,180 kg

Mission Design and Management: NASA / JPL

Launch Vehicle: Atlas V 401 (AV-007)

Launch Date and Time: 12 August 2005 / 11:43:00 UT

Launch Site: Cape Canaveral Air Force Station / SLC-41

Scientific Instruments:

• 1. high resolution imaging science experiment camera (HiRISE)
• 2. context camera (CTX)
• 3. Mars color imager (MARCI)
• 4. compact reconnaissance imaging spectrometer (CRISM)
• 5. Mars climate sounder (MCS)
• 6. shallow subsurface radar (SHARAD)
• 7. Optical navigation camera
• 8. Electra communications package
• 9. Gravity field investigation package
• 10. Atmospheric structure investigation

Results: Mars Reconnaissance Orbiter (MRO) is a large orbiter, modeled in part on NASA's highly successful Mars Global Surveyor spacecraft, designed to photograph Mars from orbit for about two Earth years. Its primary goals were to map the Martian surface with a high-resolution camera (the HiRISE 0.5-meter diameter reflecting telescope, the largest ever carried on a deep space mission), at least partly to help select sites for future landing missions. Supplementary investigations included studies of the Martian climate, weather, atmosphere, and geology. Along with the basic six instruments, MRO also carried an optical navigation camera and Electra, a UHF telecommunications package to provide navigation and communications support to other landers and rovers on the surface of Mars. After launch, MRO entered orbit around Earth. Soon after, the Centaur upper stage fired for a second time to dispatch its payload (and itself) to escape velocity on a trajectory to intercept with Mars. After a seven-month trip through interplanetary space and three mid-course corrections, MRO approached Mars and, on 10 March 2006, fired its six engines (which displayed slightly reduced thrust), and successfully entered into a highly elliptical orbit around the Red Planet with parameters of 426 × 44,500 kilometers with a period of 35.5 hours. A subsequent combination of aerobraking in the upper atmosphere and engine burns between 7 April and 11 September 2006 left MRO in its final operational orbit of approximately 250 × 316 kilometers. Two months later, it began its primary science mission, joining five other active spacecraft in orbit or on the surface of Mars: Mars Global Surveyor, 2001 Mars Odyssey, the two Mars Exploration Rovers, and the European Mars Express.

An image from the HiRISE instrument on board NASA's Mars Reconnaissance Orbiter (MRO) shows a fissure, less than 500 meters across at its widest point, on Olympus Mons on Mars. Credit: NASA/JPL-Caltech/Univ. of Arizona

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By December 2006, the operation of one of MRO's instruments, the Mars climate sounder, was suspended due to anomalies in its field of view. All other instruments, however, returned vast amounts of uninterrupted and valuable data during the first two years of MRO's operations, known as the Primary Science Phase, which extended from November 2006 to November 2008. One of the early findings from imagery collected by HiRISE was the presence of liquid carbon dioxide or water on the surface of Mars in its recent past. During the Extended Science Phase, from November 2008 to December 2010, MRO faced a number of technical obstacles, primarily related to seemingly spontaneous rebooting of its computer four times in 2009. At one point, the spacecraft was essentially shut down beginning 26 August. Finally, on 8 December, engineers commanded the orbiter out of "safe mode" and slowly began initiating science operations using its scientific instruments. As it was back on the job, MRO passed an important symbolic milestone on 3 March 2010 when it had reached 100 terabits of data transmitted back to Earth, which NASA said was "more than three times the amount of data from all other deep-space missions combined." MRO continued to return high quality data, despite another reboot event in September 2010. Many of its activities were coordinated with other Mars spacecraft. For example, in December 2010, researchers used data from the CRISM instrument to help the Opportunity rover study the distribution of minerals in Endeavour Crater on the ground. A new phase of MRO's mission began in December 2010, the Extended Mission, whose goal was to explore seasonal processes on Mars, search for surface changes, and also provide support for other Martian spacecraft including the Mars Science Laboratory (MSL). It was during this period, in March 2011, that MRO passed its five-year anniversary orbiting Mars. Later in August, NASA announced that MRO data indicated that water might actually be flowing on Mars during the warmest months of the year; MRO images had shown dark finger-like features, known as Recurring Slope Linea (RSLs) that appear and disappear on some slopes during late spring through summer but disappear during winter. On 14 March 2012, MRO captured a 20-kilometer-high dust devil whirling its way across the Amazonis Planitia region of northern Mars. Later, in October 2012, NASA initiated MRO's second Extended Mission, which expired in October 2014. Late in 2013, MRO turned its gaze outwards, to Comet ISON, a comet racing in from the Oort Cloud, which passed by Mars on 29 September. During this second Extended Mission, MRO passed the point of transmitting 200 terabits of science data back to Earth. Once again, there was a computer anomaly on board the spacecraft: on 9 March 2014, MRO put itself in safe mode after an unscheduled swap from one main computer to another. Four days later, the vehicle resumed normal science operations (along with its activities relaying data back to Earth from the Curiosity rover). Because of the impending flyby of Mars by Comet C/2013A1 (or Comet Siding Spring) on 19 October 2014, NASA began to shift the orbit of MRO (as well as its other operational orbiter, 2001 Mars Odyssey) to minimize risk of damage from material shed by the comet. Orbit adjustments were made by MRO on 2 July and then again on 27 August. In the event, MRO captured the best ever views of a comet from the Oort Cloud when Siding Spring flew by Mars on 19 October. The spacecraft also suffered no damage as a result of the flyby. For the seventh time in its time in orbit, MRO put itself in a precautionary standby mode on 11 April 2015 when there was an unplanned switch from one main computer to another. Within a week the spacecraft once again returned to full operational capability. Later, in January 2016, controllers completed a planned flash-memory rewrite in one of the spacecraft's redundant computers in order to load new data in the form of tables on the positions of Earth and the Sun. Earlier, in August 2015, MRO celebrated a decade since its launch, by which time it had orbited Mars 40,000 times and returned 250 terabits of data; NASA announced that every week, the spacecraft was still returning more information on Mars than the weekly total of all other active Mars missions. Soon after, in September 2015, scientists published evidence in the journal Nature Geoscience that data from MRO's imaging spectrometer provided the strongest evidence yet that liquid water still flows intermittently on present-day Mars. Scientists later concluded that water ice makes up half or more of an underground layer in the Utopia Planitia region. In July 2016, research results were published indicating that gullies on modern day Mars—channels with an alcove at the top and deposited material at the bottom—were probably not formed by flowing liquid water, and instead perhaps by the freeze and thaw of carbon dioxide frost. The data from MRO also provided the basis for a large crowd-sourced experiment in 2016. Using the Planet Four: Terrains Web site, ten thousand volunteers used images (taken by the Context Camera) of the Martian south polar regions to identify targets for closer inspection (by the HiRISE camera), thus generating new insights on seasonal slabs of carbon dioxide and erosional features on Mars known as "spiders." On 28 September 2016, MRO was to have provided critical communications support for the arrival of the InSight Mars lander mission (enabled in part by an orbital maneuver carried out more than a year before, on 29 July 2015). However, the InSight launch was postponed to 2018 due to development problems in one of its instruments as well as the relative infrequency of the short launch window chosen for the mission. At several points during its mission, MRO photographed artificial objects on the Martian surface. In January 2015, NASA announced that high resolution images taken by MRO had identified Beagle 2's wreckage on the Martian surface. Similarly, images taken in December 2014 and April 2015 by the HiRISE instrument also showed NASA's Curiosity rover inside Gale Crater. Later, in October 2016, images taken by both the Context Camera and the HiRISE camera showed ESA's Schiaparelli test lander that stopped transmitting before final impact. In early 2017, nearly 11 years after arriving at Mars, MRO remains operational and the second longest-lived spacecraft to orbit Mars, after 2001 Mars Odyssey.

209

Venus Express

Nation: European Space Agency (5)

Objective(s): Venus orbit

Spacecraft: VEX

Spacecraft Mass: 1,270 kg

Mission Design and Management: ESA

Launch Vehicle: Soyuz-FG + Fregat (no. Zh15000-010 + 14S44 no. 1010)

Launch Date and Time: 9 November 2005 / 03:33:34 UT

Launch Site: GIK-5 / Site 31/6

Scientific Instruments:

• 1. analyzer of space plasma and energetic atoms (ASPERA)
• 2. Venus Express magnetometer (MAG)
• 3. planetary Fourier spectrometer (PFS)
• 4. ultraviolet and infrared atmospheric spectrometer (SPICAV/SOIR)
• 5. Venus radio science experiment (VeRa)
• 6. visible and infrared thermal imaging spectrometer (VIRTIS)
• 7. Venus monitoring camera (VMC)

Results: Venus Express was a spacecraft, similar in design to ESA's Mars Express, designed to conduct a global investigation of the Venusian atmosphere, its plasma environment, and surface characteristics, from a 24-hour near-polar elliptical orbit around Venus. The spacecraft was launched by a Soyuz-FG/Fregat combination owned by Starsem, a French company which markets the Russian Soyuz in its "European" version. The Soyuz-FG delivered the payload into a low Earth orbit, with the Fregat firing a second time 96 minutes after launch to send the entire stack out of Earth orbit towards Venus. The spacecraft carried out a single mid-course correction on the way to Venus, on 11 November 2005, before arriving at Venus on 11 April 2006 after a five-month journey. The main engine fired at 07:10:29 UT (spacecraft time) to insert Venus Express into orbit around the planet, thus becoming the first European spacecraft to orbit Venus. It achieved its operational orbit—250 × 66,000 kilometers—by 7 May 2007. The original mission of Venus Express was anticipated to last no more than 500 Earth days, but the mission was extended five times past its nominal mission (which ended on 19 September 2007); it was extended first to May 2009, then to December 2009, then to December 2012, then to 2014, and finally to 2015. Among its initial accomplishments was to generate a complete temperature map of the southern hemisphere of the planet by December 2006. Further major findings included evidence for past oceans on the surface of Venus, a higher prevalence of lightning on Venus than Earth, and the discovery of a huge "double atmospheric vortex" at the south pole of the planet. In 2011, scientists studying data from Venus Express reported the existence of a layer of ozone in the upper atmosphere of the planet. After eight years in orbit, as propellant supplies to maintain its elliptical orbit began running low, routine science experiments were concluded on 15 May 2014, and mission scientists decided to undertake a series of aerobraking campaigns during which the spacecraft would "dip" deeper into the atmosphere than it had before. The lowest point of 129.1 kilometers was reached on 11 July. The duration of these "dips" was about 100 seconds long with maximum dynamic pressure at 0.75 Newton per square meter, probably a record for a spacecraft still operating in orbit around a planetary body. After about a month in late June and early July "surfing in and out" of the Venusian atmosphere, during which time critical data was collected on the effects of atmospheric drag and heating, the spacecraft performed a 15-day climb back up, beginning 12 July, which ended by reaching an orbit with a lowest point of 460 kilometers. Having reached this orbit, Venus Express decayed naturally the remainder of the year. There was an attempt in late November to arrest this decay but contact with the spacecraft was lost on 28 November 2014, with only intermittent telemetry and telecommand links after that point. On 16 December, ESA officially announced the end of the mission although a carrier signal was still being received. The last time that this X-band carrier signal was detected was on 19 January 2015, suggesting that the orbiter burned up in the atmosphere soon after.