On September 6, on the western side of the rim of Endeavor Crater, the US rover Opportunity discovered a new form of Martian rock - spherical granules with a low iron content. On September 28, NASA announced that the rover would stop at Matievich Hill for several weeks or even months to study them.
At the end of the ninth year of work, Opportunity, which during this time covered more than 35 km on the surface of Mars and studied the rocks near and inside three craters of successively increasing size. The fruitful surveys of the Mars rovers Spirit and Opportunity paved the way for the heavy rover Curiosity, which in August 2012 began research in the Martian crater Gale.
Winter's end
As we remember, on December 26, 2011, on its 2816th Martian day (sol), the Opportunity rover settled on the north-facing 15-degree slope of the Cape York Rise at the Greeley Haven point. Here the rover had to survive the time of passage of aphelion and the maximum northern declination of the Sun - that is, the time when the daily energy supply is small and it must be saved.
Indeed, on January 3, 2012, the rover received only 287 Wh, and on February 1, the receipt fell to a minimum and amounted to 270 Wh. During this period, even sessions of relaying data via satellite were not carried out every Sol, but only when there was sufficient charge in the batteries.
The rover used the forced stop to take a color panorama using a panoramic camera with 13 light filters and contact studies of the Amboy site on the Martian surface. The latter included shooting with an MI camera-microscope and long sessions of alternating measurements with two spectrometers.
The results were as expected: the rock in the Greeley Haven area turned out to be Suevite, an impact breccia, like other Cape York stony outcroppings such as Shoemaker Ridge and Chester Lake. The only exception so far has been the Tisdale stone near the Odysseus crater, which differs in texture and composition. According to an article published May 7 in Science, it contains significantly more zinc, and scientists believe that Tisdale comes from a deeper horizon than the rest of the samples studied. Interestingly, experts have found similarities between Tisdale and the rocks explored by the Spirit rover in the Gusev crater and bearing traces of hydrothermal alteration. They believe that the impact of a celestial body that gave rise to Endeavor Crater also led to the release of water and hydrothermal transformation of rocks: in particular, the appearance of zinc compounds. It is with this substance that the Endeavor Shaft is composed, and as for the rest of the samples, they represent later sediments.
The onboard radio complex Opportunity served during these months as a kind of beacon for determining the parameters of precession and nutation of the Martian axis of rotation. During the winter, more than sixty special 30-minute radio sessions took place. The scientific director of the experiment, William M. Folkner, expects - after processing the new data and comparing them with the results of 90-day observations on the Mars Pathfinder in 1997 - to improve the estimate of the rate of precession of the Martian rotational axis by two orders of magnitude. The situation with nutation is more complicated and will probably require another cycle of measurements next Martian winter, but the refinement of the precession parameters will make it possible to cut off a good half of the models of the internal structure of the planet. Further development of this experiment is planned in the specialized mission INSIGHT.
Perhaps the only incident during the wintering took place on March 20 (Sol 2899), when the IDD manipulator was programmed to turn to aim the MI camera and stopped at the signal of the security system. HazCam service camera data suggested that between March 15 and March 20, ground subsidence occurred under the rover, as a result of which the left front wheel dropped by almost 1 cm. Perhaps this movement “confused” the built-in control algorithms?
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CHRONICLE OF OPPORTUNITY |
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In March, the decision was made to stop using the MS Mössbauer spectrometer at Opportunity. Firstly, its source on radioactive cobalt-57 with a half-life of 270 days was already almost depleted, and one measurement needed 750 hours instead of 30 minutes at the beginning of the mission. Secondly, there were unpleasant problems with the operation of the device electronics at temperatures below -50°C. (Partly the loss of MS helped his lucky partner APXS - one of the constant hindrances came to naught.) |
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CHRONICLE OF OPPORTUNITY |
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On March 31, an accurate determination of the orientation of the rover was made, taking into account the position of the Sun and the "pictures" of the service cameras. New displacements were not revealed, but just in case, on April 4, the operators scrolled the wheel back and forth and turned it left and right. Shooting with an MI micro camera showed that the wheel was firmly planted on the ground.
At the end of February, and then in the last days of March, gusts of wind blew off some of the dust from the solar panels, and the energy income increased to 321 Wh. Mars was slowly moving away from aphelion (February 15) and from the solstice point (March 30), so that starting from March 10, insolation in the equatorial zone increased due to natural causes. By the end of April, the daily energy input had grown to 366 Wh - the fifth winter of Opportunity was coming to an end!
In May and June, the transparency of the atmosphere rose to a maximum, and on June 14 another tornado passed, and the light transmittance of solar-powered dust increased abruptly from 56.7 to 68.4%. As a result, the input rose to 526 watt-hours and has remained above the 500-watt mark since then.
Hello Curiosity!
Improvement in external conditions allowed Opportunity to resume traffic after a 130-day stop. This happened already on May 8 (Sol 2947), when the rover moved 3.7 m forward (to the northwest) and entered a site with an inclination of only 8°. The motors of all wheels, including the right front one, which had previously had problems with mobility, worked normally and had the expected current consumption.
The general plan of the campaign was to continue clockwise around the Cape York Rise, inspect the gypsum veins at its northern end, and then survey the inner slope. But first, the scientists wanted to find out the chemical composition of Martian dust on the small dune of the North Pole, so named because it was exactly north of the winter campsite. For the next four transitions, the rover moved another 14 m and approached the dune. From May 19 to May 25, the APXS spectrometer sniffed at the reddish soil at the “pole” and found in it an increased sulfur content compared to ordinary basalt sand.
On May 25, 27 and 31, the rover made an 80-meter throw to the northern tip of Cape York. Of the gypsum veins located there, one named Monte Cristo was chosen for detailed study. On June 2 (Sol 2971), the rover came close to it and from June 5 to June 12 conducted a multi-day measurement using APXS. The work was complicated by a failure on June 7 on the Mars Odyssey satellite, after which the scheduled relay session via MRO did not take place on the same day. The rover had to send a 32 kbps live telemetry request to the rover to make sure it was working, and in the following days, operators combined rare MRO sessions with live data. The main repeater satellite was reactivated only on June 27th.
Nevertheless, on June 12 and 20, Opportunity moved another 22 meters to the north and stopped at the border of Cape York and the surrounding plain. Here, measurements were carried out at the Grasberg and Grasberg-2 sites. The first of them was treated with a RAT brush on June 27 to remove a layer of dust, and then the rock properties were measured for two days. On June 30, multispectral images were taken with the PanCam camera, and then the rover launched the RAT cutter and cut the top 1.5 mm of the stone. On July 3, the section was photographed in detail with an MI microcamera and an APXS spectrometer head was mounted on it; measurements continued until 9 July. As a result, Grasberg was recognized as sedimentary material from the first layer after the formation of the Endeavor crater.
In the work, the American rover celebrated the jubilee, 3000th sol on Mars, which fell on July 2 according to the earth's calendar. It is worth remembering once again that the MER rovers were designed for only 90 days!
On July 10, Opportunity left the Grasberg zone and moved around Cape York. On July 12, he began moving towards the small impact crater San Gabriel, but there was a new failure on the Odyssey, the rover was left without support from orbit until the 18th and limited further work to filming and sounding the atmosphere. Meanwhile, on July 13, the MRO satellite detected a local dust storm and clouds of ice crystals condensed on dust particles near the location of Opportunity. By July 24, the transparency index of the atmosphere had deteriorated to 0.77, which corresponded to a decrease in the power of sunlight by more than half; energy, however, lacked.
On July 21, the rover approached San Gabriel, filmed it, and retreated to the Wim Creek geological site. Two sols later, Opportunity approached the Mons Couprie site, and on July 26 moved to the Rushall point. On both objects, he measured APXS "om.
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Mons Coupry site. |
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Rover OPPORTUNITY |
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During the delivery of the new rover to Mars, the program was subordinated to the operation of Curiosity. On July 31, a trial transmission session took place in the VHF band: the Opportunity transmitter imitated the operation of the radio complex of its “brother” from the surface, and the Australian Parks radio telescope successfully received the signal. After that, for nine days, from August 1 to August 9, the rover worked autonomously, without getting in touch: it conducted spectrometry at the Rushall-1 site and photographed the Wim Creek area.
Spherules of Kirkwood
On August 12, the rover moved south to the crater of San Rafael, and on the 14th it reached Berrio crater (all three craters were named after the ships of the navigator Vasco da Gama). On August 16, he walked 40 meters, and on August 18 he made a hundred meters along the western slope, filming rock outcrops along the way with navigation and panoramic cameras. The subject of the search was phyllosilicates found during spectrometric survey from orbit. On August 21, 23 and 25 another 143 meters were covered to the south; Finally, on August 28, the rover turned west to the remarkable sharp Kirkwood Ridge, and on the same day “changed” the 35-kilometer mark from the moment of landing. The total run of Opportunity as of September 12 was 35047.47 meters. During the time after the winter parking, 686 meters were covered.
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Rover OPPORTUNITY |
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The hill that now towered in front of the rover was named by the Opportunity ground team in memory of Jacob R. Matijevic, who passed away on August 20, 2012 at the age of 65 due to lung failure. A native of Chicago who graduated from the University of Chicago with a PhD in mathematics, he joined JPL in 1981. From 1992, Jake led the development of the Sojourner mini-rover, then was the head of the Mars Exploration Rover project for several years before launch and until until October 2008, and most recently served as Principal Surface Systems Engineer for the MSL/Curiosity project.
On August 29, Opportunity walked another 12 meters, after which the experts chose an object for detailed study. On September 1 and 4, the rover came close to Kirkwood - a chain of dark "feathers" up to 30 cm high sticking out of the ground - and on September 6 (Sol 3064) launched the spectrometer. At the same time, images were received on Earth: on September 4 - a general plan, and on September 6 - detailed ones, from the MI microcamera, and they amazed scientists! "This is one of the most exceptional images of the entire mission," said Opportunity's science director Steven W. Squyres. - Kirkwood harbors a dense collection of small spherical objects. Of course, we immediately remembered "blueberries", but this is something else. We have never seen such a dense accumulation of spherules on Martian rocks."
The "blueberry" mentioned by S. Squires was one of the first finds of Opportunity on the Meridian plain. These are spherical formations of iron-bearing hematite - concretions deposited from mineralized water. However, in Kirkwood's spherules, the APXS instrument did not find a high iron content, and in addition, they had a different distribution over the surface and a specific concentric structure. It was possible to see it due to the fact that some particles were destroyed and “polished” by the wind. “They seem to be brittle on the outside and softer on the inside,” Squires remarked. - Before us is a magnificent geological mystery. We have a lot of working hypotheses, but none of them is preferred yet... We need to keep the breadth of perception, and let the stones speak for themselves.”
On September 8, the rover managed to accept all the commands, but the communication session ended abnormally - the Earth turned out to be below the upper plane with solar panels! The error generated in the on-board computer was removed on September 11, and in the meantime, Opportunity brushed the sample and continued measurements.
On September 12, the rover gracefully circled Kirkwood's "feathers" and approached a vast, light-colored outcrop of Whitewater Lake, criss-crossed by numerous light-colored veins. Scientists suspected that it was this feature of the relief that fell into the field of view of the CRISM spectrometer at MRO, which found signs of hydrated rocks - phyllosilicates here.
A small turn on September 13 made it possible to bring the manipulator to the surface. The rover took measurements using APXS at the Azilda site: from September 15 on a pristine surface, and after cleaning two separate points with a brush, on these sites. Having chosen the Azilda-2 section as the most promising, the operators formed a program for its milling, which was completed on September 25-29 (sols 3083-3087). The stone turned out to be soft and made it easy to drill 3.6 mm. The spectrometer was again placed in the round recess ... But what we managed to find out, we will talk next time.
The equinox came on September 30th. The Opportunity team's plans for the spring and summer include a detailed study of the stratigraphy and compositional variations of the Whitewater Lake outcrop, Kirkwood Ridge, and other features on Matievich Hill. After that, it is likely that the rover will descend from Cape York and return to its southern tip to further explore interesting details missed in the fall due to lack of time.
Further plans include a geological trek to the south with a length of more than five kilometers. Its most important points are the Botany Bay Lowland, where, according to the data of orbital surveys, gypsum occurs not in the form of separate veins, but in a continuous massif, then the Solander Point area and the main part of the Cape Tribulation Rise with extensive clay deposits - iron-magnesium smectites.
The American rover Opportunity, which has spent 15 years on Mars, was turned off last summer due to a powerful dust storm in the Valley of Perseverance.
It successfully survived the most difficult months of the Martian "winter", but a storm that raged for several weeks made scientists doubt that Opportunity could overcome this cataclysm.
Although the storm stopped and the transparency of the atmosphere returned to normal values, the rover did not make contact. On February 13, 2019, NASA stopped trying to re-establish contact with it.
"I declare the Opportunity mission completed, and with it the Mars Exploration Rover mission completed. I have to tell you, this is an emotional moment," said Thomas Zurbuchen, NASA assistant director of science.
Currently, the Curiosity rover and the landing rover are working on the surface of Mars, and two new rovers should join them in about a year. Korrespondent.net gives details about Opportunity.
Opportunity Achievements
Opportunity worked on the planet for 5352 Martian days - sols, covering 45.16 kilometers during this time, setting a record among planetary rovers. Initially, scientists planned that the service life of the rover would not exceed three months and a kilometer of the distance traveled.
During the entire period of operation, the rover sent more than 217 thousand images to Earth, including fifteen 360-degree color panoramas of the surrounding area, set a record for the distance traveled in one day on Mars (220 meters) and analyzed several dozen rock samples.
For more than a decade, Opportunity has held the lead in planetary exploration. He told humanity about a potentially habitable planet and showed uncharted Martian landscapes.
“What the Spirit and Opportunity rovers have done on Mars is amazing. Thanks to groundbreaking missions like Opportunity, the day will come when our brave astronauts set foot on the surface of Mars. And when that day comes, some of those first footprints will belong to the Opportunity team, which has done so much in the name of discovery," said NASA chief Jim Bridenstine.
Photos Opportunity:
The storm swept across Mars
One of the main characteristics and mysteries of Mars is that scientists do not know why such storms do not occur every season and why they sometimes cover almost the entire planet.
"We've been watching Mars for 20 years and we haven't seen anything like this yet - an ordinary regional storm has grown to the size of a planetary storm, affecting not only Opportunity, but also Curiosity on the other side of the planet," said mission leader Richard Zurek.
Global map of the dust storm on Mars / NASA
The rover was in Perseverance Valley when the dust storm hit on June 1st. She prevented the penetration of sunlight through the atmosphere, leaving the rover without a power source.
Curiosity did not use solar panels as an energy source, but a radioisotope thermoelectric generator.
Within a few days, the hurricane covered a quarter of Mars, equal to the territory of North America and South America combined - about 35 million square kilometers.
These days, the sky on the Red Planet resembled the sky of the Earth during the smog.
On the left, the sky of Mars on a normal day, on the right - in a sandstorm / NASA
On June 6, NASA registered a noticeable drop in the energy level of the rover and put it into save mode. All scientific operations performed by Opportunity have been terminated.
In sleep mode, the rover turned off most of its functions, only the internal clock remained working, which forced the onboard computer to boot up and check the battery level from time to time.
The latest data shows that the temperature of the rover has dropped to -29 degrees Celsius. The minimum operating temperature of the device is -40 degrees, so then its systems worked to maintain heat in the batteries.
Dangerous for the "life" of Opportunity was the discharge of batteries below the level necessary to power the internal clock. This situation will require more complex recovery. Something similar happened to Opportunity's "twin", the Spirit rover, stuck on one of the slopes of the Gusev crater.
The brave rover Opportunity
Opportunity arrived on Mars in 2004, its mission was scheduled for 90 days. However, the apparatus withstood all the tests and continues to work, despite the fact that it has damaged its "hand" and can only move in the opposite direction.
In 2007, the rover had already experienced a major dust storm, but it was half as intense. The current sandstorm has turned day into night in Opportunity's equatorial zone.
Opportunity took its first selfie in 2018 / NASA
On June 12, 2018, NASA engineers tried to contact the rover, but failed. The rover has never had so little energy - scientists suggest that the voltage in its onboard network fell below 24 volts.
"It was a remarkable rover. Due to its durability, it made many discoveries. This little one has proved to be an invaluable investment and has greatly expanded our ability to explore the Red Planet," said Jim Watzin, director of the Mars Exploration Program at NASA.
Opportunity traveled on Mars more than other rovers - about 45 kilometers.
He found evidence of liquid water on the Red Planet. These observations allowed scientists to make assumptions about how Mars is habitable.
Before the storm forced Opportunity to go offline, he was exploring Perseverance Valley near Endeavor Crater.
The robot was trying to determine whether the valley was formed by wind erosion or water sources, or possibly both.
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These two photographs taken by Curiosity on May 21 (left) and June 17 (right) show how different the current light level of Mars, in whose atmosphere the dust storm is raging, differs from the normal situation.
It has been raging on Mars for many weeks now, which has covered almost the entire planet. Because of it, the Opportunity rover does not receive the necessary amount of sunlight, which is converted into electricity by photovoltaic cells. The rover has gone into hibernation and won't be able to wake up until the atmosphere clears of dust and the sun's rays reach the surface of Mars.
When this will happen is not yet clear, since the scale of the storm is only increasing, most likely, it will not weaken in the near future. "We haven't been able to contact the rover for a couple of weeks now," says Ray Arvidson of the University of Washington. He is one of the leaders of the Mars Exploration Rover mission, which originally included Opportunity's twin brother, the Spirit rover. Both rovers arrived on Mars in January 2004 and began to study the surface of the Earth's neighbor together.
Opportunity has been working for many years, and would have continued to work if not for the strong dustiness of the rarefied atmosphere of Mars. In the graph below, you can see how the amount of dust in the air affects the amount of power received by the rover. The system generates so little energy that it cannot take and send to Earth a photograph of what is happening around it. The last picture was taken by scientists on June 10 this year. The rover occasionally “wakes up” in order to check its energy reserves. If they are too small, the rover will go to sleep again.
As for Spirit, this rover, unfortunately, stopped showing signs of life on March 22, 2010.
Some time after the storm subsides, Opportunity should wake up, and if there is enough energy, the Earth will receive its signal. Then, when the mode of obtaining energy becomes optimal, the rover will return to work again, and who knows how many months or years it can still work.
His "big brother" Curiosity is operating normally, as it has an autonomous power supply on board. He regularly sends pictures of Mars. The photographs taken by this device after the beginning of the dust storm show that objects on the surface do not cast shadows. This is because the reptilians are playing dirty tricks. The atmosphere of Mars is so dusty that the light of the Sun is very weak. The effect is about the same as on a very cloudy day on Earth, maybe even stronger on Mars.
Scientists believe that the Opportunity rover will survive the bad weather and in a few weeks will delight with new data on the Red Planet.
