Beyond_Earth-_A_Chronicle_of_Deep_Space_Exploration_1958-2016.pdf

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Opportunity

Nation: USA (82)

Objective(s): Mars surface exploration

Spacecraft: Mars Exploration Rover 1 (MER 1) [became MER-B]

Spacecraft Mass: 1,062 kg

Mission Design and Management: NASA / JPL

Launch Vehicle: Delta 7925H (no. D299)

Launch Date and Time: 8 July 2003 / 03:18:15 UT

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

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: For description and background, see entry for Spirit. After launch, the MER-1 rover was dispatched on its six-month trek to Mars. After a final course correction on 16 January 2004, the spacecraft dived into the Martian atmosphere on 25 January 2004. The descent to the surface was uneventful with no anomalies. The lander, enclosed in the airbags, touched down at 04:54 UT and then bounced at least 26 times before coming to rest in Meridiani Planum at 1.9483° S / 354.47417° E, about 14.9 kilometers from the intended target. This area was now named the Challenger Memorial Station, in tribute to the Space Shuttle crew lost in 1986. Opportunity landed in a relatively flat plain but within an impact crater known as Eagle. After extensive studies within Eagle, on 22 March 2004, Opportunity climbed up the edge of the crater and rolled out and headed for a new phase of its mission in Endurance Crater, about 750 meters away. Having exited Eagle, the rover took some spectacular shots of the abandoned area where the lander, backshell, and parachute were still visible. Near its discarded heat shield, Opportunity discovered an unusual basketball-sized rock in January 2005 (known as "Heat Shield Rock") that turned out to be an iron-nickel meteorite. Later that year, the rover drove into an area where several of its wheels were buried in sand, rendering the vehicle immobile. JPL controllers were able to maneuver the vehicle a few centimeters at a time and free Opportunity in June 2005 after six weeks of rest. Through the remainder of the year and into 2006, the rover headed slowly in a southward direction towards the 800-meter diameter Victoria crater, first arriving at Erebus, a highly eroded impact crater about 300 meters in diameter. In March 2006, it then began its 2-kilometer journey to Victoria, a crater wider and deeper than any yet examined by the two rovers. After a 21-month trip, Opportunity arrived at Victoria in September 2006 and sent back striking pictures of its rim. The following year, 2007, was an important test for Opportunity given the severe dust storms that plagued Mars. By 18 July, the rover's solar panels were reporting power at only 128 watt-hours, the lowest for either rover at that point. All science activities were indefinitely suspended for Opportunity which faced much more severe conditions than Spirit. After about six weeks and abatement of the dust storms, Opportunity was back in action, and on 11 September 2007, it entered Victoria Crater, staying inside for almost a year sending back a wealth of information on its soil. Opportunity's next target was the enormous Endeavour Crater, 22 kilometers in diameter. On the way there, the rover found the so-called Marquette Island rock, "different in composition and character from any known rock on Mars or meteorite from Mars," according to Steve Squyres (1956– ), the principal investigator for the rovers. The rock appeared to have originated deep in the Martian crust and someplace far away from the landing site, unlike almost all the rocks previously studied by Opportunity. On 24 March 2010, Opportunity passed the 20-kilometer milestone on Mars, more than double the distance recorded by Spirit, and far in excess of what was originally considered a nominal mission—600 meters. Two months later, on 20 May—with Spirit already inactive—Opportunity broke the record set by the Viking 1 Lander for the longest continuous operation on the surface of Mars, 6 years and 116 days. Another milestone was passed when Opportunity, still heading towards Endeavour Crater, passed the 30-kilometer mark on 1 June 2011. Finally, after a journey of nearly three years and about 21 kilometers, Opportunity arrived at Endeavour crater on 9 August 2011. In September 2011, NASA announced that an aluminum cuff that served as a cable shield on each of the RATs on the rovers was made from aluminum recovered from the World Trade Center towers, destroyed during the terrorist attacks on 11 September 2001. Honeybee Robotics, which helped build the tool, had its offices in New York that day not far from the attacks. As a memorial to the victims, JPL and Honeybee worked together to include the aluminum on the Mars rovers. Through late 2012 and into 2013, Opportunity worked around a geographic feature named Matijevic Hill (which overlooks the Endeavour crater), analyzing rocks and soil. On 16 May 2013, NASA announced that Endeavour had passed the previous record for the farthest distance traveled by any NASA vehicle on another celestial body, 35.744 kilometers, a record set by the Apollo 17 Lunar Roving Vehicle in December 1972. By August 2013, Opportunity was at Solander Point, an area of contact between a rock layer that was formed in acidic wet conditions long before and an older one from a more "neutral" environment. Both Cape York (location of Matijevic Hill) and Solander Point are raised segments near the western rim of the Endeavour crater. On 4 January 2014, Opportunity passed 10 years on the surface of Mars, now with relatively clean surfaces on the solar panels that had allowed increased power to the rover. A "selfie" from March 2014 showed a rover cleaned by wind events earlier in the month that raised hopes for continuing the mission. As it continued its exploration mission on the Martian surface, on 28 July 2014, NASA announced that Opportunity had passed the distance record set on another celestial body, set by Lunokhod 2, when the American rover's odometer showed 40.25 kilometers, exceeding the Soviet vehicle's record of 39 kilometers. However, Russian analysis from LRO images suggest that Lunokhod 2 may have traveled as much as 42 kilometers, rather than the revised 39 (itself a "revision" up from 37 kilometers). While the rover was generally in good health, because of the large number of computer resets in the preceding month, which interfered with its science goals, mission planners implemented a complete reformat of its flash memory on 4 September 2014. The same day, NASA announced a further (ninth) extension of the mission of Opportunity to another two years with a mission to nearby Marathon Valley. At the beginning of September, it had covered 40.69 kilometers. At launch, like its sister rover, Spirit, Opportunity was designed to have a lifetime of 90 sols (Martian days)—about three Earth months. In December 2014, NASA announced that the rover had been plagued with problems with saving telemetry information into its "non-volatile" (or flash) memory, a problem traced to one of its seven memory banks (Bank 7). By May 2015, NASA controllers configured the memory so the rover was operating only in RAM-only mode. On 25 March 2015, NASA announced that, having traveled 42.195 kilometers (or 26.219 miles), Opportunity became "the first human enterprise to exceed marathon distance of travel on another world." In June 2015, because Mars passed almost directly behind the Sun (from Earth's perspective) and therefore communications were curtailed. Later, through its seventh Martian winter (during Earth winter 2015–2016), at a time when it was kept at "energy-minimum" levels due to the relative lack of solar energy, Opportunity kept busy, using its Rock Abrasion Tool to remove surface dust from a target called "Private John Potts," the name a reference to a member of the Lewis and Clark Expedition. During this period, Opportunity continued to explore the western rim of the 22-kilometer wide Endeavour crater, particularly the southern side of Marathon Valley, which slices through Endeavour crater's rim from west to east. On 10 March 2016, while making its closest approach to a target near the crest of Knudsen Crater, it drove at a tilt of 32°, breaking the record for the steepest slope driven by any rover on Mars (a record previously set by Opportunity during a climb in January 2004). In October 2016, Opportunity began a two-year extended mission that is to include investigations in the "Bitterroot Valley" portion of the western rim of the Endeavour Crater. The plan is for the rover to travel into a gully that slices Endeavour and is about two football fields in length. Opportunity Principal Investigator Steve Squyres noted that scientists were "confident [that] this is a fluid-carved gully, and that water was involved." On 7 February 2017, Opportunity passed the 44-kilometer mark on its odometer, as it made slow progress towards its next major scientific objective, a gully named Perseverance Valley, which it reached by the first week of May. Having collected several panoramas of high-value targets in the gully, on 4 June, the rover experienced a problem due to a stall on the left front wheel, which left the wheel "toed out" by 33 degrees. Fortunately, after several straightening attempts, the wheel appeared to be steering straight again, although controllers could not identify any conclusive cause for the problem. For about three weeks during June and July, there was reduced communication with the rover due to a solar conjunction (when the Sun comes between Earth and Mars). In mid-July, Opportunity finally entered Perseverance Valley and began driving down into the gully during which time, rover energy levels dropped due to reduced Sun exposure. As of 31 October 2017, Opportunity's odometer read 45.04 kilometers.

210

SIRTF / Spitzer Space Telescope

Nation: USA (83)

Objective(s): solar orbit

Spacecraft: Space Infrared Telescope Facility (SIRTF)

Spacecraft Mass: 950 kg

Mission Design and Management: NASA / JPL / Caltech

Launch Vehicle: Delta 7920H (no. D300)

Launch Date and Time: 25 August 2003 / 05:35:39 UT

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

Scientific Instruments:

• 1. infrared array camera (IRAC)
• 2. infrared spectrograph (IRS)
• 3. multiband imaging photometer for Spitzer (MIPS)

Results: SIRTF was the fourth and last of NASA's "Great Observatories," after the Hubble Space Telescope (launched in 1990), the Compton Gamma Ray Observatory (1991), and the Chandra X-Ray Observatory (1999). It carried an 85-centimeter infrared telescope and three scientific instruments as part of the Cryogenic Telescope Assembly (CTA). Its planned two-and-a-half-year mission was designed to detect infrared radiation from its vantage point in heliocentric orbit. The CTA was cooled to only 5 degrees above absolute zero (or a temperature of –268°C) using 360 liters of liquid helium, ensuring that the observatory's "body heat" did not interfere with the observation of relatively cold cosmic objects.

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The Delta II Heavy (in a two-stage Delta 7925H configuration) inserted the second stage and payload into an initial orbit of 166 × 167 kilometers at 31.5° before the second stage ignited again at 06:13 UT on 25 August 2003 to send both the stage and the observatory into a hyperbolic orbit where SIRTF, by 3 September passed into an "Earth-trailing orbit" around the Sun. It ejected its dust cover on 29 August and then opened its aperture door the day after. In this orbit, at 0.996 × 1.019 AU, Earth (rather prominent in the infrared) does not hinder observation of potential targets of observation. On 18 December 2003, the SIRTF was renamed the Spitzer Space Telescope in honor of Lyman S. Spitzer, Jr. (1914–1997), one of the first to propose the idea of using telescopes in space. One of the early successes of the mission (in 2005) was to capture direct light from extrasolar planets for the first time. Many other findings followed in the subsequent four years, including seeing the light from the earliest objects in the universe, mapping the weather on an extrasolar planet for the first time, finding water vapor on another extrasolar planet, and identifying a new ring (the Phoebe ring) around Saturn. The observatory worked far longer than expected and its supply of liquid helium finally depleted at 22:11 UT on 15 May 2009, nearly six years after launch. At that point, mission scientists reformulated the mission as the Spitzer Warm Mission, which would use the two shortest-wavelength modules of the IRAC instrument, which did not require the cryogenic helium to operate, for future observations. More discoveries followed. In August 2010, for example, data from Spitzer revealed the identification of the first Carbon-rich planet (known as WASP-12b) orbiting a star. In October 2012, astronomers announced that data from the observatory had allowed a more precise measurement of the Hubble constant, the rate at which the universe is stretching apart. The following year, Spitzer celebrated 10 full years of operation in space and continued operation of its two instruments which, in August 2014, observed an eruption of dust around a star (NGC 2547-ID8), possibly caused by a collision of large asteroids. Such impacts are thought to lead to the formation of planets. Continuing discoveries based on results from Spitzer (as well as data integrated with information from other space-based observatories such as Swift) were announced in April 2015 (discovery of one of the most distant planets ever identified, about 13,000 light-years from Earth) and in March 2016 (discovery of the most remote galaxy ever detected, a high-redshift galaxy known as GN-z11). The latter was detected as part of the Frontiers Field project that combines the power of all three of NASA's Great Observatories, Spitzer, Hubble, and Chandra. In August 2016, mission planners at JPL announced a new phase of the Spitzer mission known simply as "Beyond," leveraged on a two-and-a-half-year mission extension granted by NASA earlier in the year. Because the distance between Spitzer and Earth has widened over time, during Beyond, its antenna must be pointed at higher angles towards the Sun to communicate with Earth. As a result, parts of the spacecraft will experience increasing amounts of heat. Simultaneously, its solar panels will be pointed away from the Sun in this configuration, thus putting onboard batteries under more stress. These challenges will be a part of the Beyond phase as Spitzer continues to explore planetary bodies both within and beyond the solar system. In October 2017, NASA announced that it was seeking information from potential funders who might be able to support operation of the telescope after NASA funding runs out in March 2019. With such possible funding, it might be possible to operate Spitzer beyond September of that year when operations are expected to cease with government funding.