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95-485: The Meridiani Planum is one of the most thoroughly investigated regions of Mars. Many studies were carried out by the scientists involved with NASA's Mars Exploration Rover (MER) Opportunity . Two outstanding features found by these investigations are the actions of water flow and aqueous chemistry in this plain's geological history and, particularly specific to the plain, an abundance and ubiquity of small spherules composed mainly of grey-hematite that sit loosely on top of

190-454: A "second landing site". The Opportunity mission is considered one of NASA's most successful ventures. Due to the planetary 2018 dust storm on Mars, Opportunity ceased communications on June 10 and entered hibernation on June 12, 2018. It was hoped it would reboot once the weather cleared, but it did not, suggesting either a catastrophic failure or that a layer of dust had covered its solar panels. NASA hoped to re-establish contact with

285-486: A Mars rover, the small, short-lived Sojourner . Mars Global Surveyor surveyed most of the surface of Mars to map its surface topography, some mineral distributions, and make some other measurements. An important survey carried out between 1997 and 2002 by the Mars Global Surveyor collected surface hematite levels with the satellite's thermal emissions spectrometer (TES). The TES hematite survey data

380-418: A base level of heating, assisted by electrical heaters when necessary. Communications depended on an omnidirectional low-gain antenna communicating at a low data rate and a steerable high-gain antenna, both in direct contact with Earth. A low-gain antenna was also used to relay data to spacecraft orbiting Mars. The science instruments included: The rover arm held the following instruments: Opportunity

475-404: A clarifying article on February 16, making it clear he had taken statements from NASA officials who were interpreting the data sent by Opportunity , both on the state of its low power and Mars's high atmospheric opacity, and rephrased them in a poetic manner, never to imply the rover had sent the specific words. Honoring Opportunity' s great contribution to the exploration of Mars, an asteroid

570-575: A clockwise direction. In June 2007 it returned to Duck Bay, its original arrival point at Victoria crater; in September 2007 it entered the crater to begin a detailed study. In August 2008, Opportunity left Victoria crater for Endeavour crater , which it reached on August 9, 2011. At the rim of the Endeavour crater, the rover moved around a geographic feature named Cape York . The Mars Reconnaissance Orbiter had detected phyllosilicates there, and

665-471: A few meters of their starting embedded location. The surface hematite spherules and sediments are coextensive in surface area. So, the area extent of the underlying sediments is at least as large as the area of detected surface hematite spherules but likely somewhat larger since, for example, a significant area of surface hematite was covered by ejecta from the Bopolu Crater impact. The typical depth of

760-438: A few minutes each day. Due to the 2018 dust storms on Mars, Opportunity entered hibernation mode on June 12, but it remained silent after the storm subsided in early October. Opportunity has provided substantial evidence in support of the mission's primary scientific goals: to search for and characterize a wide range of rocks and regolith that hold clues to past water activity on Mars . In addition to investigating

855-567: A geochemical model that generates hematite within a context like the Meridiani sediment. The hematite formed into spherules by concretion . The concretion process to form near spherical balls (spherules) of hematite probably occurred by diffusion of the hematite through the sedimentary rock matrix (the hematite still in the rock matrix probably fixed in place when moveable water disappeared). The results of these transformations are still largely intact today. The main subsequent changes just affected

950-481: A group of five standard oxides (MgO, Na 2 O, P 2 O 5 , SO 3 , and Cl) each had content above trace-level with a combined group content of 6.8 +/- 2.4 wt%, the SiO 2 levels ranged between 8 wt% and 0 wt%, and the other eight APXS standard oxides had either 0 wt% content or only trace level content. The underlying soils at Meridiani Planum are similar to those at Gusev Crater, Ares Vallis, and Gale Crater; although,

1045-446: A hyper-hydrated magnesium sulfate on Earth that they called meridianiite (after Meridiani Planum), with the formula MgSO 4 .11H 2 O, which decomposes to epsomite , MgSO 4 .7H 2 O, and water at 2 C. Opportunity 's Alpha particle X-ray spectrometer (APXS) found rather high levels of phosphorus in the rocks. Since the solubility of phosphorus is related to the solubility of uranium , thorium , and rare-earth elements , it

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1140-404: A large planetary-scale dust storm developed, and within a few days the rover's solar panels were not generating enough power to maintain communications, with the last contact on June 10, 2018. NASA stated that they did not expect to resume communication until after the storm subsided, but the rover kept silent even after the storm ended in early October, suggesting either a catastrophic failure or

1235-435: A layer of dust covering its solar panels. The team remained hopeful that a windy period between November 2018 and January 2019 might clear the dust from its solar panels, as had happened before. Wind was detected nearby on January 8, and on January 26 the mission team announced a plan to begin broadcasting a new set of commands to the rover in case its radio receiver failed. On February 12, 2019, past and present members of

1330-417: A meteorite on Earth known to have come from Mars. Bounce rock received its name by being bounced on by the airbags of Opportunity' s lander. The other rock, "Marquette Island," is believed to have originated deep inside the crust of Mars. Both "Bounce Rock" and "Marquette Island" are considered to be ejecta from large crater impacts occurring off the plain at large distances from where these rocks were found by

1425-468: A non-polar region. The WEH maps are likely to underestimate the present-day water resources at Meridiani Planum since (a) the HEND has a shallow (1 m) penetration depth, (b) the majority of the plain's surface is covered in dehydrated soils, and hematite spherules. Starting with Daniel S. Goldin's strategies and NASA 's engineering attention to detail, Mars Exploration Rover Opportunity successfully made

1520-509: A planned 90- sol duration of activity (slightly less than 92.5 Earth days), Spirit functioned until it got stuck in 2009 and ceased communications in 2010, while Opportunity was able to stay operational for 5111 sols after landing, maintaining its power and key systems through continual recharging of its batteries using solar power , and hibernating during events such as dust storms to save power. This careful operation allowed Opportunity to operate for 57 times its designed lifespan, exceeding

1615-407: A similar sediment outcrop surface to Figure 14. However, Opportunity 's Rock Abrasion Tool abraded this surface. Such abrasions showed that (a) the sediment layers are very soft and easy to cut, and (b) the hematite spherules have uniform internal structures. The "diagenetic" transformation (i.e., change by water-rock interactions) to today's sediments involved a significant shift in water flows in

1710-465: A story of "an underdog beating the odds," and its "familiar, almost biologically inspired shape." The media attention surrounding Opportunity' s shutdown spread this usage to the general public. With word on February 12, 2019, that NASA was likely to conclude the Opportunity mission, many media outlets and commentators issued statements praising the mission's success and stating their goodbyes to

1805-411: A total of 2.0 wt% for the other seven standard oxides. A Mössbauer spectrum was made of the dust that gathered on Opportunity ' s capture magnet. The results suggested that the magnetic component of the dust was titanomagnetite, rather than just plain magnetite , as was once thought. A small amount of olivine was detected which was interpreted as indicating a long arid period on the planet. On

1900-465: Is a robotic rover that was active on Mars from 2004 until 2018. Opportunity was operational on Mars for 5111 sols (14 years, 138 days on Earth). Launched on July 7, 2003, as part of NASA 's Mars Exploration Rover program, it landed in Meridiani Planum on January 25, 2004, three weeks after its twin, Spirit (MER-A), touched down on the other side of the planet. With

1995-570: Is the extreme levels of the sulfates. These are about 5 times higher than the overlying Meridiani soils, about 20 times higher than in the basalts in Gusev Crater (investigated Spirit , the sibling MER), and even more extreme relative to typical Earth rocks. The principle sulfates are hydrated magnesium sulfates (e.g., kieserite & epsomite ), hydrated calcium sulfates (e.g., bassanite & gypsum ), and jarosite (a complicated hydrated sulfate containing iron and probably potassium or sodium);

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2090-541: The Mars Exploration Rover program in the long-term Mars Exploration Program . The Mars Exploration Program's four principal goals were to determine if the potential for life exists on Mars (in particular, whether recoverable water may be found on Mars), to characterize the Mars climate and its geology, and then to prepare for a potential human mission to Mars. The Mars Exploration Rovers were to travel across

2185-403: The "Arkansas Group" that were breccias displaying evidence of material melting from heat generated by meteorite impacts. The rover found two odd boulders with mineralogies significantly different from the plain's common sediment rocks. One rock, "Bounce Rock," contains mainly pyroxene and plagioclase but no olivine. It closely resembled a part, Lithology B, of the shergottite meteorite EETA 79001,

2280-658: The "hole-in-one" landing into Eagle Crater at Meridiani Planum on January 24 (PST), 2004. NASA named this landing site the Challenger Memorial Station to honor the final crew of the Space Shuttle Challenger , who died in 1986 when that shuttle broke up in flight. The Meridiani Planum was also the target landing site for two other missions: Mars Surveyor 2001 Lander and Schiaparelli EDM . However, these other two lander missions were not successful. The Mars Surveyor 2001 Lander

2375-576: The Martian surface and perform periodic geologic analyses to determine if water ever existed on Mars as well as the types of minerals available, as well as to corroborate data taken by the Mars Reconnaissance Orbiter (MRO). Both rovers were designed with an expected 90 sols (92 Earth days) lifetime, but each lasted much longer than expected. Spirit 's mission lasted 20 times longer than its expected lifetime, and its mission

2470-468: The Martian surface by January 2004. Opportunity ' s launch was managed by NASA's Launch Services Program . This was the first launch of the Delta II Heavy. The launch period went from June 25 to July 15, 2003. The first launch attempt occurred on June 28, 2003, but the spacecraft launched nine days later on July 7, 2003, due to delays for range safety and winds, then later to replace items on

2565-666: The Meridiani Planum and around the rim of Endeavour Crater between January 2004 and June 2018. Figure 2 highlights the rover's traverse route (yellow line). The route's position within the Meridiani Planum is shown by the blue line traverse route labeled "OT" in Figure 1b. The journey started on January 25, 2004, with the landing in Eagle Crater . The rover crossed the plain's sediments and soils and studied many small and medium-sized craters until August 2011, when it reached

2660-399: The Meridiani Planum are both very slow (relative to water-related erosion on Earth and early Mars) but also extremely fast (about 30 to 300 times faster) when compared to other arid regions of Mars (such as Gusev Crater). Figure 17 shows hematite spherules as they turned from being embedded spherules into loose spherules. In Figure 17, right around seven blocks of eroding sediment ejecta (from

2755-475: The Meridiani Planum. However, both missions also included satellites (operating between 1976 and 1982 ) that took many images of the surface of Mars from orbit. Viking 1 and Viking 2 satellite images of what is today called the Meridiani Planum (and its adjacent regions) were studied in three works in the 1980s and again in two 1997 papers published in the months between the launch of the Mars Global Surveyor mission and its arrival at Mars. Edgett and Parker noted

2850-574: The Miniature Thermal Emission Spectrometer ( Mini-TES ), Mossbauer spectrometer , and APXS led researchers to classify Heat Shield Rock as an IAB meteorite with close to 93 wt% iron content and 7 wt% nickel content (mostly in metallic form). Heat Shield Rock (see Figure 8) was the first meteorite recognized on another planet. (The other MER, Spirit , found two rocks in Gusev Crater, "Allan Hills" and "Zhong Shan," that may be iron meteorites.) The top layers of

2945-528: The above processes and added details. Christensen's rapid assessment of the erosional processes was probably connected to his correct 2000 prediction that the plain's surface material is soft and easy-to-erode (friable). And that prediction was made after orbiter data showed that Meridiani Planum is very smooth and that small craters degrade and disappear more rapidly than in adjoining regions. Opportunity found that Meridiani sediments are soft and friable. More satellite and rover data showed that erosion rates on

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3040-639: The battery and power system in one Sol, but this could vary due to a variety of factors. In Eagle crater the cells were producing about 840 Wh per day, but by Sol 319 in December 2004, it had dropped to 730 Wh per day. Like Earth, Mars has seasonal variations that reduce sunlight during winter. However, since the Martian year is longer than that of the Earth, the seasons fully rotate roughly once every 2 Earth years. By 2016, MER-B had endured seven Martian winters, during which times power levels drop which can mean

3135-405: The chloride salts include halite and bischofite. Detecting jarosite was a surprise, and its presence significantly constrains the possible geochemical pathways leading to the formation of Meridiani sediments. Water Content? An outstanding unknown is the amount of residual water in the layered sediments today. Answers from direct measurement by the rover Opportunity were not possible because

3230-488: The coincidental (somewhat arbitrary) fact that the plain straddles the prime meridian for the system of longitude lines introduced for east/west Mars mapping. The area covered by the detected surface hematite is around 150,000 km, i.e., larger than Lake Superior (82,000 km (32,000 sq mi)) in North America. Except for transport by large meteor impact, loose surface spherules tend to remain within

3325-413: The common and outstanding features a person would see standing at locations along Opportunity 's traverse of the Meridiani Planum. The dominant visual impressions at eye level are that: This section covers the composition of the major materials found at the Meridiani plain (i.e., sediments, spherules, soils, and dust). The discoveries and compositions of meteorites and long-distance ejecta are given in

3420-399: The composition of the spherules and some published papers cited these conference claims. However, there were reasons to be cautious. The instruments detected mixed signals from sampling targets that included signals not only from the spherules but also from dust and rock (in the "berry bowl" experiment) or dust and soils (in other composition data collections). In 2006, Morris et al. showed that

3515-549: The composition of this dust is essentially uniform everywhere, due to the many dust storms over Mars, including global dust storms every few years. Opportunity 's APXS measurement of a commonly referenced dust-covered sampling target, MontBlanc_LeHauches, gives a dust composition that is largely basaltic in character with the following weight perecentages for the standard oxides: 45.3 wt% SiO 2 , 17.6 wt% Fe0, 9.2 wt% Al 2 O 3 , 7.6 wt% MgO, 7.3 wt% SO 3 , 6.6 wt% CaO, 2.2 wt% Na 2 0, 1.0 TiO 2 , 0.9 wt% P 2 O 5 , and

3610-411: The confirmation (from the topography mapping done by the Mars Global Surveyor ) that this area is a flat plain and relatively easy to land on were the decisive pieces of evidence for choosing the Meridiani Planum as one of the landing sites for NASA's two bigger Mars Exploration Rovers (MERs), named Opportunity and Spirit . The decisiveness for NASA of the hematite map of Figure 1b for choosing

3705-435: The determinants of solar power production) varied from a relatively dusty 0.467 on December 5, 2013 (sol 3507), to a relatively clean 0.964 on May 13, 2014 (sol 3662). In December 2014, NASA reported that Opportunity was suffering from " amnesia " events in which the rover failed to write data, e.g. telemetry information, to non-volatile memory . The hardware failure was believed to be due to an age-related fault in one of

3800-399: The distance in 11 years and 2 months. The JPL technicians celebrated the occasion by running a race. A documentary film, Good Night Oppy , about the Opportunity , Spirit , and their long missions, was directed by Ryan White , and included support from JPL and Industrial Light & Magic . It was released in 2022. The rover could take pictures with its different cameras, but only

3895-423: The drilling mechanisms". Solar arrays generated about 140 watts for up to fourteen hours per sol, while rechargeable lithium ion batteries stored energy for use at night. Opportunity ' s onboard computer uses a 20 MHz RAD6000 CPU with 128 MB of DRAM and 3 MB of EEPROM. The rover's operating temperature ranges from −40 to +40 °C (−40 to 104 °F) and radioisotope heaters provide

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3990-508: The earliest Mars map-makers, Johann Heinrich von Mädler and Wilhelm Beer , chose to place the prime meridian for maps of Mars through this dark spot. In the late 1870s, Camille Flammarion called this dark region Sinus Meridiani ("Meridian Bay"). The Meridiani Planum covers the western part of the Sinus Meridiani. The Viking 1 and Viking 2 missions successfully landed the first landers on Mars at locations far away from

4085-471: The emergence of the enormous Tharsis Plateau and the vast volcanoes of Tharsis several thousand kilometers away. From around the late- Noachian /early- Hesperian to sometime around 3.5 billion years ago, the layered sediments deposited in the earlier Noachian epoch were transformed. This transformation probably included a significant additional deposition of high-sulfur-content material of volcanic origin. The change certainly included aqueous geochemistry that

4180-431: The end of January 2019 with over 1000 recovery commands transmitted before February 13, 2019. NASA officials held a press conference on February 13 to declare an official end to the mission. NASA associate administrator Thomas Zurbuchen said, "It is therefore that I am standing here with a deep sense of appreciation and gratitude that I declare the Opportunity mission is complete." As NASA ended their attempts to contact

4275-480: The height of 1.5 m, i.e., a height similar to the eye height of most people. The Pancam was used to take scientific data, and it also took images that were approximate true color (ATC) photographs of the rover's surroundings; that is, the Pancam photographed images close to what people would see if standing in the rover's place. The following pictures, Figure 3 through Figure 10, provide a selection of images that cover

4370-405: The hematite-bearing plain were operationally defined in the late 1990s and early 2000s by the extent of the orbital detection of the plain's surface hematite by the thermal emission spectrometer (TES) on the satellite Mars Global Surveyor . The various names for this region (i.e., Terra Meridiani, Meridiani Planum) started to be used in the published literature in 2002/2003/2004. Each name reflects

4465-408: The higher ground in the southeast (lower right of Figure 13) toward the northwest and down to the present-day Meridiani Planum. The river valleys seen in Figure 13 terminate abruptly as they flow into the Meridiani's massive formation of sediments. Current evidence points to the sloping ground (necessary for the river flows) being created by a giant tilt in the surface of Terra Meridiani Mars caused by

4560-493: The initial plan by 14 years, 47 days (in Earth time). By June 10, 2018, when it last contacted NASA, the rover had traveled a distance of 45.16 kilometers (28.06 miles). Mission highlights included the initial 90-sol mission, finding meteorites such as Heat Shield Rock (Meridiani Planum meteorite), and over two years of exploring and studying Victoria crater . The rover survived moderate dust storms and in 2011 reached Endeavour crater , which has been considered as

4655-404: The landing site for Opportunity was due to the fact that NASA was using high hematite levels as proxy evidence for large amounts of liquid water flowing in the region in the past (hematite only forms in the presence of liquid water in geological settings). In 2003, this high-hematite region was a high-priority place to start to search for signs of life on Mars. Since 2001, evidence for water at

4750-588: The layer of water-poor top soil covering most areas of Meridiani). In 2005 the measured WEH level at Meridiani was 7 wt%, but continued neutron detection produced a 2018 WEH map indicating 9-10 wt% WEH across Meridiani. There is a small field of scientific study concentrating on how hydration levels of hydrated magnesium and calcium sulfates vary with temperature at Martain atmosphere pressures. At Martian pressures, these studies readily extracted water from magnesium sulfates with various levels of hydration using applied temperatures between 50 C and 200 C. They also observed

4845-508: The levels of sulfates in Meridiani soils are noticeably higher than other locations. At Meridiani Planum, the soils are armored with a thin top layer of hematite spherules with their distinct composition (not found at Gusev Crater, Ares Vallis, and Gale Crater). This layering of spherules (and spherule fragments) on top, with basaltic soils below, is shown in Figure 12. Most of the underlying soil consists of basaltic material but mixed with varying amounts of dust and sulfate-rich ejecta debris from

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4940-461: The methods used by some researchers to pick out the spherule composition signal from the dust and soil signals were flawed and that such methods could do no more than constrain the iron oxide content of the spherules to between 24 wt% and 100 wt% (that is, almost no constraint at all). A 2008 paper published the result of a clever experiment that showed Opportunity 's mini-TES (thermal emission spectrometer) could not detect any silicate minerals in

5035-401: The mid-1990s were to gather some evidence for surface water using satellite surveys and to land robotic rovers on the surface to collect detailed local evidence of water and signs of life. Two NASA missions arrived at Mars in mid-1997: Mars Pathfinder and Mars Global Surveyor . Mars Pathfinder made the first successful Mars landing in over twenty years and the first-ever deployment of

5130-789: The mission team gathered in the Jet Propulsion Laboratory (JPL)'s Space Flight Operations Facility to watch final commands being transmitted to Opportunity via the 70-meter (230-foot) dish of the Goldstone Deep Space Communications Complex in California. Following 25 minutes of transmission of the final 4 sets of commands, communication attempts with the rover were handed off to Canberra, Australia . More than 835 recovery commands were transmitted since losing signal in June 2018 to

5225-681: The next section. A later section covers the geological materials found by Opportunity after August 2011, i.e., around the rim of Endeavour Crater. The layered sedimentary outcrop rocks exposed in Eagle, Fram, and Endurance caters were examined by the suite of instruments on Opportunity . Mature data analysis found the following (broad category) mineral composition of the sediments (excluding embedded spherules): 36-37 wt% hydrated sulfates, 35 wt% hydrated aluminosilicates, 16 wt% basaltic rock, 10 wt% hematite and other oxides, 2 wt% chlorides, and 1-2 wt% phosphates. An outstanding feature of this composition

5320-482: The other hand, a small amount of hematite that was present meant that there may have been liquid water for a short time in the early history of the planet. Opportunity found six large iron-nickel meteorites just sitting on the plains ( Heat Shield Rock (shown in Figure 8), Block Island , Shelter Island , Mackinac Island , Oileán Ruaidh , and Ireland), although these six may originate from fewer impacts (i.e., an original meteor broke into pieces). Examination with

5415-416: The plain's soils and underneath embedded inside its sediments. The loose surface spherules were eroded out of the sediments. They are informally called "blueberries". The plain's sediments have extremely high sulfur content (as sulfates) and high phosphate levels. The boundaries of the Meridiani Planum are not firmly fixed and accepted by the community of Mars planetary scientists. However, the boundaries of

5510-526: The plain's soils contain a noticeable content (~1 wt%) of small-particle, iron-nickel meteoritic material - many iron-nickel meteorites disintegrate during descent and impact, and these pieces were too small for the Pancam to identify. Stony meteorites are more challenging to identify than iron-nickel meteorites. However, the cobble named "Fig Tree Barberton" and three others in the "Barberton group" are thought to be stony or stony-iron meteorites (mesosiderite silicate),. Opportunity studied nine cobbles in

5605-402: The presence of hematite and past presence of water on the surface of Mars. Following this, it was directed to travel across the surface of Mars to investigate another crater site, Endurance crater , which it explored from June to December 2004. Subsequently, Opportunity examined the impact site of its own heat shield and discovered an intact meteorite , now known as Heat Shield Rock , on

5700-579: The present-day Meridiani Planum was collected by the High Energy Neutron Detector (HEND) mounted on the Mars Odyssey orbiter. This neutron detector collects signals of "water-equivalent hydrogen" (WEH) over the entire planet. It gradually built up global maps of surface WEH. These maps show that polar and near-polar regions of Mars have the highest levels of surface WEH; although, the Meridiani Planum has relatively high WEH for

5795-625: The primary agents of change to the plain. This slower change was and is driven by meteorite impacts, the wind, and gravity. Over the hard-to-grasp eon of around three billion years, meteorite impacts, and the wind formed the sandy topsoil and loose hematite spherules and sorted these into the layered soil bedforms that Opportunity 's Pancam photographed, and we can now see. The meteorite, gravity, and wind-driven processes work like this: Phil Christensen outlined these processes in 2004, soon after Opportunity landed. Later, more in-depth research (with more years of data from Opportunity ) confirmed

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5890-407: The region. The inflows from rivers became less and less, and in this period, the dominant water movements in the sediments became vertical movements with rising and falling aquifer levels. At least one model of global Martian hydrology accounts for the historical shift in water flows at Meridiani Planum. This model links Meridiani's change in water flows to activity in the volcanic Tharsis region. With

5985-400: The rim of the enormous Endeavour Crater. Between August 2011 and June 10, 2018, it studied the rim of Endeavour (which has different geological features from the plain). The rover's last communication with NASA was on June 10, 2018. The Opportunity mission was declared ended on February 13, 2019. The Opportunity rover had five cameras. One, the Pancam (panoramic cam), was mounted at

6080-626: The rocket (insulation and a battery). Each day had two instantaneous launch opportunities. On the day of launch, the launch was delayed to the second opportunity (11:18 p.m. EDT) in order to fix a valve. On January 25, 2004 (GMT) (January 24, 2004, PST), the airbag-protected landing craft settled onto the surface of Mars in the Eagle crater. From its initial landing into an impact crater amidst an otherwise generally flat plain, Opportunity successfully investigated regolith and rock samples and took panoramic photos of its landing site. Its sampling allowed NASA scientists to make hypotheses concerning

6175-412: The rover analyzed the rocks with its instruments to check this sighting on the ground. This structure was analyzed in depth until summer 2013. In May 2013 the rover was heading south to a hill named Solander Point . Opportunity ' s total odometry by June 10, 2018 (sol 5111), was 45.16 km (28.06 mi), while the dust factor was 10.8. Since January 2013, the solar array dust factor (one of

6270-522: The rover avoids doing activities that use a lot of power. During its first winter power levels dropped to under 300 Wh per day for two months, but some later winters were not as bad. Another factor that can reduce received power is dust in the atmosphere, especially dust storms. Dust storms have occurred quite frequently when Mars is closest to the Sun. Global dust storms in 2007 reduced power levels for Opportunity and Spirit so much they could only run for

6365-414: The rover's demise in 2018. The plain's sediments do not cover this crater rim and are geologically younger than this rim. As such, the rim of Endeavour Crater is distinct from the plain, although it is surrounded by the plain and its sediments. The Meridiani Planum was first observed as part of a larger region that appeared as a distinct dark (low albedo) spot in small telescope images of Mars. Around 1830

6460-399: The rover's instruments could not detect water or hydrogen. However, in 2005, Clark et al. gave a range of 6 wt% to 22 wt% based on an indirect geochemical argument. Further, the actual water content should be higher than the water equivalent hydrogen (WEH) measurements made by the neutron detector orbiting on Mars Odyssey (due to the shallow (1m) penetration depth of the neutron detector and

6555-457: The rover's seven memory banks. As a result, NASA had aimed to force the rover's software to ignore the failed memory bank; amnesia events continued to occur, however, which eventually resulted in vehicle resets. In light of this, on Sol 4027 (May 23, 2015), the rover was configured to operate in RAM-only mode, completely avoiding the use of non-volatile memory for storage. In early June 2018,

6650-529: The rover, citing a recurring windy period which was forecast for November 2018 to January 2019, that could potentially clean off its solar panels. On February 13, 2019, NASA officials declared that the Opportunity mission was complete, after the spacecraft had failed to respond to over 1,000 signals sent since August 2018. The scientific objectives of the Mars Exploration Rover mission were to: Opportunity and Spirit rovers were part of

6745-475: The rover, the last data sent was the song " I'll Be Seeing You " performed by Billie Holiday . Assets that had been needed to support Opportunity were transitioned to support the Curiosity rover and the then-upcoming Perseverance rover. The final communication from the rover came on June 10, 2018 (sol 5111) from Perseverance Valley, and indicated a solar array energy production of 22 Watt-hours for

6840-507: The rover. The history of geological change at Meridiani Planum fits into three epochs with distinct processes. These three eras of change at Meridiani align reasonably well with the three standard epochs for the whole planet, i.e., the Noachian , Hesperian , and Amazonian epochs. Prior to the formation of Meridiani's defining sediments, in the wet Noachian (named for the biblical Noah) more than about ~3.7 billion years ago, liquid water

6935-626: The rover. One journalist, Jacob Margolis, tweeted his translation of the last data transmission sent by Opportunity on June 10, 2018, as "My battery is low and it's getting dark." The phrase struck a chord with the public, inspiring a period of mourning, artwork, and tributes to the memory of Opportunity . When the quote became widely reported, some news reports mistakenly asserted that the rover sent that exact message in English, resulting in NASA being inundated with additional questions. Margolis wrote

7030-443: The sediment rock matrix that appeared (cropped) in a prestigious paper. Figure 14 illustrates the four physical constituents of sediment outcrop: (i) the sedimentary layers containing a lot of basaltic sand particles; (ii) the embedded hematite spherules; (iii) fine-grained, sulfate-rich cement (in most parts of the outcrop); (iv) vug cavities (that are thought to be molds for crystals of, for example, hydrated sulfates). Figure 15 images

7125-473: The sediments. A typical mineral composition for basaltic Meridiani soils is 40 wt% plagioclase, 35 wt% pyroxenes, 15 wt% amorphous glasses, 10 wt% olivine, and around 5 wt% sulfates and oxides. Standard oxide compositions for typical basaltic soils are 44-46 wt% SiO 2 , 18-19 wt% FeO + Fe 2 O 3 , 9-10 wt% Al 2 O 3 , 7.4 wt% MgO, 6.9 wt% CaO 2 , 5.8 wt% SO 3 , 2.2 wt% Na 2 O, ~5 wt% other oxides (total). Dust covers everything all over Mars and

7220-657: The smooth terrain of what we now call the Meridiani Planum and realized early that the plain was likely made of sediments and probably had a wet, watery past. In the 1990s, NASA officials, especially Daniel S. Goldin , wanted to delineate a framework for "faster, better, cheaper" exploration of Mars. In this context, the "Water Strategy" was outlined in 1995/1996. The "Water Strategy" was "to explore and study Mars in three areas: - Evidence of past or present life, - Climate (weather, processes, and history), - Resources (environment and utilization)." All three areas were seen as intimately connected to water. High priority goals for NASA in

7315-427: The sol, and the highest atmospheric opacity (tau) ever measured on Mars: 10.8. Opportunity (and its twin, Spirit ) are six-wheeled, solar-powered robots standing 1.5 meters (4.9 ft) high, 2.3 meters (7.5 ft) wide and 1.6 meters (5.2 ft) long and weighing 180 kilograms (400 lb). Six wheels on a rocker-bogie system enabled mobility over rough terrain. Each wheel had its own motor. The vehicle

7410-479: The spectrometer's field of view (FOV), while the other had around 25 spherules in the FOV. Figure 11 shows the adjacent "berry bowl" sampling targets. The APXS results indicated there was noticeably more iron in the target with ~25 spherules relative to the target with 0 or 1 spherules. Based on this and similar experiments, several unreviewed conference abstracts claimed (deliberately not cited here) that hematite dominated

7505-415: The spherules (allowable = consistent with the silicate non-detection). The lowest and highest weight percentages for the iron oxide content in these allowable spherule compositions were, respectively, 79.5 wt% and 99.8 wt%. While, for the large majority of the allowable compositions, the iron oxide contents in the spherules were between 85 wt% and 96 wt%; further, the nickel content was always close to 0.3 wt%,

7600-530: The spherules. This non-detection constrained silicate levels in spherules to less than 10 wt% and probably below 8 wt%. This result is helpful since the APXS data shows a strong anti-correlation between silicates and iron oxide in the spherules - so low silicate levels indicate high iron oxide levels. A recent paper used the mini-TES's non-detection of silicates and some improved data analysis methods to find over 340,000 allowable standard oxide chemical compositions for

7695-400: The surface of Mars. Opportunity was directed to proceed in a southerly direction to Erebus crater , a large, shallow, partially buried crater and a stopover on the way south towards Victoria crater , between October 2005 and March 2006. It experienced some mechanical problems with its robotic arm. In late September 2006, Opportunity reached Victoria crater and explored along the rim in

7790-516: The tiny Granada Crater) are rings surrounding these blocks where these rings are formed by locally high surface concentrations of loose spherules and caused by additional loose spherules eroding out of the blocks of sediment. Figure 17 is cropped from Figure 7, which was, in turn, cropped from Figure 9. Click and enlarge Figure 17 to see the high-density rings of spherules. Opportunity (rover) Opportunity , also known as MER-B ( Mars Exploration Rover – B ) or MER-1 , and nicknamed Oppy ,

7885-547: The top layers of the Meridiani sediments (more below). The period of rising and falling aquifer levels ceased, and no water flowed on Meridiani Planum thereafter. Although, when this happened is poorly understood. Estimates include around 3.5 billion years ago and about 3 billion years ago. The only water left at the plain was and is bound in rocks. Erosion with water flows in earlier eras was much faster than in this last (and present) arid epoch. However, erosion did not stop. Other much slower erosional processes continued and became

7980-419: The underlying sediments is several hundred meters. The Meridiani plain's sediments overlay older geological formations that appear around the sediments' boundary. The plain's sediments and surface hematite spherules were formed in three geological epochs and by three different sets of geological processes (more below). The MER Opportunity rover investigated the rim of Endeavour Crater from August 2011 until

8075-451: The vertical aquifer flows, it is believed that (playa) lakes repeatedly formed and disappeared as the aquifer levels rose and fell. (The dry area around Utah's Great Salt Lake is a playa.) The Opportunity team found minerals ("evaporites") that typically form when salty water evaporates; these evaporites cemented together other components of the sediment (such as basaltic particles and the spherules). McLennan and his students constructed

8170-419: The water, Opportunity has also obtained astronomical observations and atmospheric data. Following its launch, Opportunity was anthropomorphized by its operators: the rover was called a "she," drawing from nautical tradition , and given an affectionate nickname, "Oppy." One scientist, who worked with Opportunity for over a decade, attributed this to the rover's unexpectedly long lifespan, which he called

8265-410: Was 'driven' by several operators throughout its mission, including JPL roboticist Vandi Verma . The rover uses a combination of solar cells and a rechargeable chemical battery. This class of rover has two rechargeable lithium batteries , each composed of 8 cells with 8 amp-hour capacity. At the start of the mission the solar panels could provide up to around 900 watt-hours (Wh) per day to recharge

8360-488: Was acidic and salty, as well as rising & falling water levels: Features providing evidence include cross-bedded sediments, the presence of vugs (cavities), and embedded hematite spherules that cut across sediment layers, additionally the presence of large amounts of magnesium sulfate and other sulfate-rich minerals such as jarosite and chlorides. Jarosite formation requires aqueous acidic conditions below pH 3. Figures 14 and 15 show Microscopic Imager close-up images of

8455-688: Was canceled after the failures of the Mars Climate Orbiter and Mars Polar Lander missions, while the Schiaparelli EDM (Entry, Descent, and Landing Demonstrator Module) system lost control during the descent stage and terminally crash-landed on October 19, 2016. ( Schiaparelli EDM was part of the ExoMars program of the European Space Agency.) Opportunity traveled 28.06 miles (45.16 kilometers) across

8550-532: Was declared ended on May 25, 2011, after it got stuck in soft sand and expended its power reserves trying to free itself. Opportunity lasted 55 times longer than its 90 sol planned lifetime, operating for 5498 days from landing to mission end. An archive of weekly updates on the rover's status can be found at the Opportunity Update Archive. Spirit and Opportunity were launched a month apart, on June 10 and July 8, 2003, and both reached

8645-430: Was named Opportunity: 39382 Opportunity . The name was proposed by Ingrid van Houten-Groeneveld who, along with Cornelis Johannes van Houten and Tom Gehrels , discovered the asteroid on September 24, 1960. Opportunity ' s lander is Challenger Memorial Station . On March 24, 2015, NASA celebrated Opportunity having traveled the distance of a marathon race, 42.195 km (26.219 mi). The rover covered

8740-508: Was present and plentiful enough to form river channels that bought and deposited large quantities of basaltic silt to the current Meridiani region. Edgett and Parker could barely discern some of these river valleys in the Viking orbiter images from the 1970s. However, they are easy to see in thermal inertia images taken in orbit by Mars Odyssey and reproduced in Figure 13 (click on it for higher resolution). These river channels took water from

8835-427: Was steered at front and rear and was designed to operate safely at tilts of up to 30 degrees. The maximum speed was 5 centimeters per second (2.0 in/s); 0.18 kilometers per hour (0.11 mph), although the average speed was about 1 centimeter per second (0.39 in/s). Both Spirit and Opportunity have pieces of the fallen World Trade Center 's metal on them that were "turned into shields to protect cables on

8930-604: Was suggested these other metals are also enriched in Meridiani outcrop sediments. Early on, Opportunity 's Mössbauer spectrometer took data that determined that the iron mineral component of these spherules is dominated by hematite. However, the Mössbauer spectrometer provided no information about the mineral components of these spherules that do not contain iron. The "berry bowl" experiment took alpha particle X-ray spectrometer (APXS) readings of two sampling targets just centimeters apart: One had no (zero or one) spherules in

9025-399: Was turned into the low-resolution map shown in Figure 1a. This map, covering all of Mars, has just one large spot covering a region with high hematite levels. This green, yellow, and red spot straddles the equator and the prime meridian in the middle of Figure 1a. A higher resolution image of the high-hematite region is shown in Figure 1b. In early the 2000s, the hematite map of Figure 1b and

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