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A.J.S. Rayl • November 5, 2018
Floors 5221-5251
October came and went without a beep from Opportunity, a silence that was still not a surprise to some, but a little discouraging for other members of the Mars team. Rovers Exploration (MER).
"We are still waiting," said SEP Principal Researcher Steve Squyres at the end of the month at Cornell University.
But as ghosts and goblins prepared to haunt the streets of the world, NASA headquarters announced good news. The MER team now has the green light to continue "in the near future" its two-prong strategy of actively listening and ordering to find the signal for Opportunity and passively listen to the most sensitive radio receivers in the Deep Space Network (DSN) to try to make contact. with the rover.
NASA / JPL-Caltech / Cornell / ASU / J. Sorenson
Work in progress
It is the panorama of colors on which Opportunity worked until some Martian soil or days.
before the dust phenomenon that surrounds the planet (PEDE) puts an end to all scientific operations and causes
the robotic field geologist to go out and go into sleepy survival mode in June 2018. James
Sorenson treated this image to true colors. Black sections, it is clear that the rover was
Always work on it. "I hope when or" if "Opportunity wakes up, that she can continue to finish it,"
said Sorenson. "She still has work to do!" There is a team of scientists and engineers and
The MER followers around the world who are in complete agreement.
The ad, which appeared on the MER mission homepage on October 29th, was the best "treat" that the MER team could have hoped for Halloween and relieved a lot of pressure. This means that the operations engineers will be able to continue searching for Opportunity during the dust cleaning season, when the Martian winds clean up the solar panels of the rover.
"We know that the period from November to January 2019 corresponds to an annual dust-cleaning period at the Endeavor Crater Opportunity website," Squyres said. "Active listening in January increases our chances of hearing the mobile if the bays are very dusty now."
A monster storm – known as the Dust Event Around the Planet (PEDE) – has brought Opportunity to stop working in Perseverance Valley, to stop and switch to survival mode earlier this month of June. Although it was officially declared complete in September, the secondary or decay phase of PEDE, in which all the dust released into the atmosphere settles on the surface, can still be persistent.
The atmosphere and the sky above Opportunity have cleared a nearly normal and blurred summer level. Despite this, the rover continues to pick up dust. "When you're out of dust season on Mars, the dust builds up on the rover," said John Callas, MER Project Leader, of the Jet Propulsion Laboratory (JPL), who was at the helm. Origin of all Mars spacecraft from NASA.
There is no way to know for sure, but MER scientists and Power team members are virtually certain that Opportunity is loaded with dust, perhaps more than ever, and that the rover is in serious need of to be cleaned with dust, as indicated previously. MER Updates. If this is the case, the solar mobile would not get enough sunlight to produce the energy it needs to recharge its batteries, wake up and call home.
"My feeling persists that it's likely that a lot of dust has been raised and dropped locally," said Mark Lemmon, a member of the Sea Science Athena Science Team and an expert on the atmosphere, of the Institute of Space Sciences. "This is true for most people in Mars. The curiosity was covered with dust and even the vertical surfaces became dusty. This is especially true for Opportunity, at the epicenter of the storm. "
In fact, the curiosity was cleaned to dust between September 14th and October 25thJoy Crisp, an MSL Project Scientist, confirmed that during the time she had an anomaly memory problem requiring the Mars Science Laboratory (MSL) team to switch from one computer to another. . "What Curiosity saw was that a lot of fine material – gray powder from the shallow drilling attempt and the loose, dark reddish-brown regolith – was washed to the spot where we tried to drill the Inverness target, "she said. "We do not know exactly when the release took place at that time because we had very few images acquired during the mobile anomaly."
Space Science Systems NASA / JPL-Caltech / Malin
An omen for Oppy?
Curiosity suffered an anomaly memory problem in mid-September and Mars Science
Laboratory (MSL) did not see the workspace and rover target, Inverness, for more than a month.
month. "And there were surprises in store for us!" Melissa Rice, MER collaborator, and
a scientist participating in MSL, wrote on the MSL blog. In the Mastcam images above, the rock
was covered with gray-colored residue, but when the team cast a new look on Oct. 25th, here is!
The residue and much of the dark brown soil and reddish dust had disappeared. "The winds were
move, clean the workspace, "noted Rice, of Western Washington University. On the
On the other side of Mars, Opportunity is waiting for the winds to clear its solar panels.
Although Curiosity is on the other side of the planet, his good fortune reminds us that it is still summer and therefore still the dust storm and the dust cleaning season in the southern hemisphere of Mars. And the images of this rover are proof that the Martian winds are unleashed here and there.
Would it be an omen that the winds are already rising in Endeavor and that the dusting season will soon arrive in Meridiani Planum, the region where Endeavor Crater and Opportunity are located? Time and maybe the rover will say it in the coming weeks
The Martian winds and the upcoming dusting season were key elements of the MER team's recommendation to agency officials to continue to be allocated, actively and passively listening to the rover since early September.
During the last week of October, during a teleconference, MER's Head of Mission, Matt Keuneke, took over from Callas, who was on leave, and presented a record of accomplishments of the team and the arguments of the operation engineers to continue their current strategy. January 2019. With Squyres, Ray Arvidson, Senior Research Associate, and Abby Fraeman, MER Project Assistant Scientist, also on the line, the director of the FPL's Mars Exploration Directorate on Mars, Fuk Li, and the director of NAS 's exploration program at NASA headquarters, Jim Watzin, listening and with the agreement.
A few days later, the team learned that it had obtained NASA approval. "We are happy to continue doing everything reasonable to reconnect with Opportunity," said Keuneke.
The willingness to continue to reach out and listen as they have been has boosted morale significantly. "It really energized us," said Michael Staab, space systems engineer and flight director, who has been working for several months on various aspects of the team's recovery strategy. "I think there is a lot of dust on the boards and the rover has not been able to wake up and talk to us yet. We just have to wait for dusting season and we can do it, "he said.
"We are obviously delighted that NASA wants us to do our best to try to recover this vehicle," Callas added at the end of the month. "If we hear the rover, it will be fantastic. It will be just a phenomenal feat and we will all rejoice. For the moment, we have no data, "he added, tempering his remarks. "We have only speculation, and that weighs on self-confidence."
It's fair to say that everyone hoped that NASA-JPL would have heard the rover beep, even those who believe that Opportunity's solar panels are covered with a thick layer of powdery Martian dust. "We were hoping to hear something and we had not heard anything yet," said Rich Zurek, Mars Scientist at JPL, who is also a Mars Reconnaissance Orbiter (MRO) project scientist. "But there are still things to try, and the dusting season should begin soon."
Angela George (left); Jim Summaria (right), both via Creative Commons Wikimedia
The MER cheers inspired by Mel Brooks
The opportunity and the MER team received the full support of The Who (right) and inspired the
a single Mel Brooks (left) in October. Brooks (left) is a filmmaker, actor, comedian and
extraordinary composer whose film Spaceballs motivated the engineers at MER ops. Who –
Roger Daltrey, John Entwistle, Keith Moon and Pete Townshend photographed here from a concert at
1975 in Chicago – began in 1964 in London and was produced in Woodstock in 1969.
Moon died in 1978, shortly after Updated MER celebrated author Who are you at
evening listening with the band on the set of Battlestar Galactica at Universal Studios, and Entwistle
who died in 2002, Daltrey and Townshend continue to keep The Who on the road.
Meanwhile, the entire world is watching – even The Who, one of the most influential and influential bands in rock'n roll, and the one and only filmmaker-director-actor-actor inimitable, Mel Brooks. When Staab posted the team's wake up song for sweep control and beeping activity on October 20th– Who's classic, "I Can See For Miles" – meets the band two days later: "Wake up, Mars The Who are here!"
And, like Staab, ready to listen actively on October 24th, he is inspired by Brooks' 1987 film Spaceballs and re-nicknamed "Sweep, Beep, and Creep" just for fun on his Twitter account. Brooks responded promptly. He loved it.
NASA's extra time does not mean the MER mission team can relax, even though the holidays are getting closer. As long as the rover does not call home, these team members will remain in an enhanced state of alert and preparedness that they call DUSTCON 1, a term that they have adapted from the DEFCON system. US Army, which includes five levels of defense readiness.
"DUSTCON 1 is not an official designation," said Jennifer Herman, JPL's MER Manager. "It's something that some of us, members of the operations team, have invented for fun and inspiration, to remind us to stay ready," she said. "We have not heard of our spacecraft, our tactical preparation is always on high alert. When we hear about Opportunity and go back to nominal operations, we can reduce it. "
The rover and destiny of the mission can all be up to Mars. For the moment, for the team, it's about continuing the preparation, keeping the faith and believing in the possibilities, as in the beginning. However, team members miss Opportunity, the world's longest robot on Mars. "It's pretty much a disappointment," said Matt Golombek, MER Project scientist. "It's been a long time, and the rover is part of our family."
Everyone agrees that hearing March's beep and handing Opportunity online, and then off again, would be an unparalleled triumph, and they are doing everything in their power to make that happen. "We do not want to give up and leave:" Well, it was the dust storm, we tried, "said Herman, echoing the feelings of other team members and followers around the world. "No. We want her to come back!
JPL-Caltech, B. Barker
DUSTCON 1
When MER Power Team Leader Jennifer Herman suggested the team be ready
the rating scale, a bit like DEFCON, of the US Army, Brian Barker, JPL operating engineer,
creative and designed a graphic that appeared in Herman's workspace the next day. "DUSTCON
1 is not an official designation, "said Jennifer Herman, responsible for MER, of the JPL. "It's just
something that some of us, members of the operations team, have set up for fun and inspiration, to remind us
ourselves to stay ready, "she said. Our tactical readiness is on high alert.
It has been almost five months since the MER team was last briefed by Opportunity and the telemetry back home was breathtaking. In this downlink, which the team received on June 10, 2018, the rover revealed that it was producing only a surprisingly low energy count of 22 watts-hour and that the Atmospheric opacity was 10.8, the highest mission ever recorded on the surface of Mars. But the telemetry was not sufficient to determine the amount of dust on the solar panels with the June 10 data.th downlink, said Herman.
According to Bruce Cantor of Malin Space Science Systems, an observer of Martian dust storms since then, this PEDE has proven to be the worst global storm on Mars since 2001. The massive event has finally entered its phase of disintegration at the end of August and ended in September, as indicated in the last issue of The point on the MER.
During the phase of disintegration of these PEDE, all the dust raised in the Martian atmosphere falls back and settles on the surface of the planet. By the end of September, the sky had cleared substantially, but not completely. The Tau, what the team calls the measurement of dust in the atmosphere, bounced around the range 1.1-1.3, or a little higher in October, according to Cantor, who uses Mars Color Imager images (MARCI ) on board the MRO. with models to make estimates. Although the sky is still foggy, these measurements are "typical for storm-free conditions" in the late spring and summers on the red planet, he said.
NASA / JPL-Caltech / MSSS / UA / add-ons L. Crumpler (left) / P. Stooke (right)
The road of opportunity is long and winding
The golden line on the left image shows the route of Opportunity from the crater of the eagle.
Landing site at Cape Tribulation, which is north of its current location in Perseverance
Valley. The basic image of the map is a mosaic of images taken by the context camera.
aboard the MRO. Larry Crumpler, New Mexico Museum of Natural History and
Science, provided the road. The graph on the right shows the movements of the rover to Sol 5100
(May 29, 2018) and its approximate present location. Phil Stooke, author of the
International Atlas of Mars Exploration, Volumes 1 and 2, (The Cambridge University Press),
of the University of Western Ontario, Canada, documented this graph with soil and site
annotations. The basic image was taken by the HiRISE camera also aboard the MRO.
October turned out to be a bit like September for MER in terms of active scanning and sounding beeps, listening and commanding to try to find the signal for Opportunity and to make the rover react, and passive listening on the global Deep Space Network (DSN) network. network of transmitters and receivers around the Earth, explained in detail in the latest issue of The point on the MER.
Operations engineers continued throughout the month to experiment with increased search for DSN space and at different frequencies during the many sweeps and beeps issued each day by engineers during their DSN time. "We have only one uplink session allocated per day because the DSN is in great demand," Staab said. "But when we do the scanning, we send several commands during a single session."
They tried something new in October, just in case there was a possibility that Engineers and Opportunity may not communicate in the same wave configuration.
"There are two modes on the signals, what is called left circular polarization (LCP) and right circular polarization (RCP)," said Zurek. On the right circular polarization, the vector rotates in the right direction with respect to the direction of propagation of the signal, and the left circular polarization in which the vector rotates in the left direction. "Normally, we use the right circular polarization, because that is what all spacecraft use to control and the DSN configures it for it routinely."
However, there are certain scenarios and failure modes in which Opportunity may have tried to recall the right circular polarization and, for some reason, engineers on Earth have not heard it. The mobile has switched to the circular polarization of the wave and the left polarization. then began to switch between the two.
NASA / RadioFan / Creative Commons Wikimedia
JPL Space Ops Mission Control
This image shows a panoramic view of the Space Flight Operations Center at Jet
Propulsion Laboratory (JPL) in Pasadena, California. This is where the mission engineers and
Scientists communicate and monitor the spaceship of their mission via the Deep program
Space Network (DSN). The DSN is the only international network of antennas providing
the communication links between the mission team on Earth and the spacecraft,
Rovers on Mars. The network is composed of three communication facilities in the deep space
placed about 120 degrees from each other in the world: in Goldstone, California
Mojave Desert; near Madrid, Spain; and near Canberra, Australia, a strategic investment
this allows a constant observation of spacecraft when the Earth rotates on its own axis.
That's why engineers are turning to LCP for scans and beeps to see if they can get a response from the mobile. "If Opportunity is on the opposite polarization, it may be why we have not heard about it," Staab said.
Engineers must stay on a polarization during scanning and beeping, so they must plan in advance the tracks they will order on LCP and the ones they will order on CPR, Staab summarized.
Sunday, October 21ststAfter reconfiguring the receivers and DSN transmitters, the team moved from RCP to LCP for soundings and beeps, said Staab, who during the process as flight director works with engineers, called Aces, who monitor and communicate with the satellite via the DSN from the JPL. "I have a tracking chart showing when we are sending orders and most of our attempts are in this window's ideal location where we think the rover may have woken up and that, until we reach the end of the day, we'll be able to see what's happening. now the coverage is satisfactory. But again, it's probably a little too early for him to wake up because of the amount of dust on the solar panels, "he said.
Moreover, according to Staab, Opportunity can only be awake for about an hour each day. "It's optimistic if we are seriously do not dirty, he says.
This reality places the chances of catching this window, the time when they could receive a command from the rover, at only about 10%, estimated Staab. "So, the chances are very high for us in the current situation in which we find ourselves," he said. "If we clean up, chances increase dramatically," he said.
But Opportunity may not have been able to wake up and stand long enough to receive orders. "Opportunity may wake up for two minutes, then stop, and it may not be enough time to get an order," Staab said. "Right now, we may not even have all time to get an order in the mobile. But that's what we're waiting for now. All the rising dust falls and will fall on the rover. The fact that we have not heard yet makes me think that Opportunity is really dirty. "
NASA / JPL-Caltech
Listening to opportunities
At the end of October 2018, the headquarters of NASA gave the green light to the MER team "for the
predictable "to pursue its two-pronged strategy, both active and passive,
listen to find the Opportunity signal. "It really energized us," said Spacecraft
Systems Engineer / Flight Director Michael Staab, who has been working for months on
various aspects of the Mission Recovery Strategy.
One thing the team is certain at the moment is that the mobile has triggered three errors: a low-power error; a timer fault up-loss; and a fault of mission clock. "The mission clock has long since disappeared, so the rover does not know what time it is, and he could wake up at unusual times, because of the algorithm's operation," Golombek said.
Nevertheless, engineers from the JPL radio-science team and the MER mission managers and / or flight directors should be able to capture the signal from Opportunity through the passive listening effort during the day on Mars. Every day, they search for the mobile signal over a wide range of times and frequencies recorded by DSN receivers, the most sensitive radio receivers in the world. "We passively listen to almost all DSN tracks going to Mars, and we would. see the rover he was trying to say "Hello" even though we were not actively listening, "Golombek recalled.
While the power models suggest leaving enough energy for Opportunity to wake up from time to time, all the assumptions about the extreme dustiness of the rover suggest that it needs a good gust of wind to clean up a wind. part of the accumulated dust in her solar panels she can call home or answer the beeps. For SEA scientists, October was a September rehearsal. "Every day, the engineers informed us of the updates. It was a model in which only the soil number was changed, "said Arvidson, from the University of Washington in St. Louis.
There has been a lot of discussion about other possible reasons why Opportunity may not have telephoned home yet, besides being dust laden. It is not surprising then that members of the operations team, as well as those who have been following the mission from the beginning, wonder if the two connected rover batteries could be exhausted or damaged in some way or in any way. another, even dead.
However, it is unlikely that the batteries will be completely exhausted, said Marshall Smart, one of the key technical staff members of the JPL Group's Electrochemical Technologies group. "The batteries are pretty sturdy. Even though the batteries may be depleted and frozen for months, if they are properly reheated and recharged, it is likely that they should display operational capability, although they may be degraded, "said Smart, a chemist specializing in organic products, with Kumar Bugga. Senior member and computer engineer for the Li-ion (Li-ion) battery MER, has developed the electrolyte that enters the battery cells to withstand the brutal temperatures beyond zero on Mars.
Esprit's batteries experienced a similar under-voltage, to a lesser extent, when they were discharged too much, due to the "flash memory anomaly" during the first month of the rover's main mission said Bugga. "But they recovered and performed very well long after that," he said. "Another low-voltage episode occurred with Curiosity's protoflight batteries, where several cells were discharged at less than 1 volt. However, the batteries have recovered and supported system integration and testing, but with reduced performance, higher impedance, and reduced capacity, "he said.
NASA / JPL-Caltech / Cornell
Oppy's body, brain, heart and power supply
The diagram on the left shows the basic structure of the Mars Exploration Rovers scientific research suite.
instruments. The diagram on the right shows the inside of the body of the rover, aka the Warm
The electronic box (WEB) protects the brain and heart of the rover and is just below the
the solar panel "winglets". It indicates the location of the RAD6000 computer that serves as the
brain. In addition to the parallel lithium ion battery pack (bottom left) that powers the mobile and the others
electronic, it is housed in the electronic module Rover (REM), which is located inside the WEB
protected from icy Martian nights.
As a result, it is likely that Opportunity batteries will recover and become operational once they receive adequate electrical charge from the solar panels, Bugga said. "Although their deep discharge may cause some performance losses, this loss may be less in their current" frozen "state."
So, even if Opportunity does not have enough energy to use its heaters to keep its batteries warm during the global storm, they should still work. This does not mean that there is no way to damage them. "If the batteries are really cold and you try to charge them too quickly, it could be damaging to their health, for example, by smearing reactive lithium on the surface of the carbon anodes," said Smart.
"But this lithium electrodeposition is unlikely in a completely discharged battery; it is more likely that the batteries will simply not accept the charge due to their high impedance at these low temperatures. This can cause the battery to self-warm up at higher temperatures, where the load is kinetically achievable, "Bugga explained.
However, if the battery voltage drops too much, it could reduce the capacity and performance of the battery, said Smart. "If the voltages of the batteries and cells that compose them are exhausted, a mode of degradation can occur, resulting in a permanent loss of capacity and an impedance growth."
Therefore, even if the batteries are heated and charged gracefully, they can exhibit degraded performance compared to their health state before being depleted and frozen, "as observed with Curiosity protoflight batteries," noted Bugga.
Could the mission clock have worked in part or even in PEDE and constantly empty the batteries to the point of killing them effectively?
NASA / JPL-Caltech
MER batteries: a dynamic duo
Despite some rumors, Opportunity batteries may be dead or damaged beyond
Kumar Bugga and Marshall Smart, experts on JPL's MER batteries, who have developed
the electrolyte that goes into the cells of the batteries to resist the brutal beyond the freezing
on Mars, do not think it's the case. If the battery voltage
trop faible, cependant, cela pourrait réduire la capacité de la batterie et les performances
dire. Mais cela ne veut pas dire que le rover ne peut plus continuer, une fois récupéré et
retour au statut nominal.
"Cela est moins probable en raison des faibles courants requis pour l'horloge de mission, ce qui rend les effets de sous-tension moins impactants, en particulier à ces basses températures", a déclaré Bugga. Smart est d’accord: «Je ne pense pas que ce scénario entraîne la destruction des batteries. Comme mentionné ci-dessus, permettre aux batteries de se décharger à très basse tension n'est pas sain pour la batterie et entraînera probablement une perte de performance. Mais cette occurrence ponctuelle ne devrait pas être catastrophique. De plus, les effets néfastes de la vidange des batteries à basse tension ne sont pas aussi graves à très basses températures, car le taux de dégradation, qui implique la dissolution du collecteur de courant en cuivre anodique, sera plus lent. "
Il est également possible que quelque chose, quelque part sur la rover, se soit cassé. "Nous devons accepter le fait qu'il s'agit d'un rover âgé de 14 ans et demi", a déclaré Callas. «Rappelez-vous mon analogie, c’est la différence entre votre neveu de 17 ans qui se trouve à l’extérieur sans veste et votre grand-mère de 97 ans qui se trouve à l’extérieur sans veste. Nous sommes la grand-mère de 97 ans. "
Bien qu'il n'y ait aucune preuve ou raison de croire que quelque chose se soit cassé sur le rover, il n'y a tout simplement pas moyen de le savoir sans aucune donnée provenant d'Opportunity. Sauf en cas de casse ou de mission catastrophique, tout semble tomber en poussière. Confondant encore plus les choses, il n’ya aucun moyen de savoir avec certitude à quel point la poussière est tombée sur ce véhicule. Considérant que le PEDE recouvrait littéralement la planète entière, il est difficile de comprendre le rover would not être sale de poussière.
«Oui, c’était une tempête de poussière géante et il y avait un centre de levage à proximité, mais on ne sait pas dans quelle mesure cela tombe localement par rapport au reste de la planète, ce qui a peut-être été un facteur majeur,» dit Golombek. do not pour avoir au moins assez d'énergie pour charger la batterie suffisamment pour qu'elle se réveille, il faudrait qu'il y ait une quantité extraordinaire de poussière sur les panneaux solaires, probablement plus que jamais auparavant. »
C’est exactement ce que Lemmon, Herman, Staab et d’autres pensent depuis quelques mois. "Mon idée est que, à moins que quelque chose ne soit cassé, les panneaux solaires d’Opportunity doivent être recouverts de beaucoup de poussière, au point de bloquer plus de la moitié de la lumière qui les frappe, peut-être jusqu’à 80 ou 90%", a déclaré Herman.
"Je pense que c'est plus de la moitié à cause des résultats de certaines simulations de puissance que j'ai effectuées", a poursuivi Herman. Les entrées étaient les positions connues du mobile et de Mars, ainsi que des estimations de Tau des orbiteurs. «J'ai supposé différentes quantités de poussière sur les panneaux solaires, allant de suffisamment de poussière pour bloquer 10% de la lumière solaire à assez pour bloquer 90% de la lumière solaire», a-t-elle déclaré. «Si moins de la moitié de la lumière du soleil est bloquée par la poussière, les baies devraient produire suffisamment d’énergie pour nous permettre d’entendre parler de Opportunity à ce stade. La seule chose qui ait du sens – mis à part quelque chose qui est cassé – est que plus de la moitié de la lumière du soleil frappant les panneaux est bloquée par la poussière accumulée », a-t-elle déclaré.
En fait, la tempête a peut-être provoqué la formation de grosses particules qui auraient pu se déposer sur les matrices du rover, et ces grosses particules pourraient expliquer en partie le blocage de la lumière du soleil, comme indiqué dans le dernier numéro de Le point sur le MER. «De nombreux articles suggèrent cela et montrent que les particules les plus grosses se déposent à proximité de la zone de levage», a déclaré Lemmon.
NASA / JPL-Caltech / Cornell / ASU
La malédiction et le baiser des vents martiens
Opportunity a utilisé son Pancam pour prendre les autoportraits ci-dessus, en janvier 2014 (à gauche),
quand ses panneaux solaires ont été recouverts de poussière poudreuse martienne, et fin mars 2014
(à droite) après que les vents de Mars aient chassé une grande partie de la poussière des matrices. As the
Les vents martiens cèdent, ils emportent aussi. Malédiction et bénédiction, les vents de Mars
ont permis au rover de vivre longtemps et de prospérer. À quel point opportunité est sale en ce moment
à la suite des retombées de la tempête de poussière entourant la planète qui a éclaté en juin
Juillet et août 2018, personne ne le sait. Mais les vents martiens devraient commencer à se lever et
soufflant dans Endeavour lorsque la saison de dépoussiérage commence à la mi-novembre.
Puisque Opportunity est censé être très proche d’une zone de levage pendant des jours, si des objets plus volumineux étaient soulevés, comme proposé par ces scientifiques de l’atmosphère, ils auraient peut-être été déposés sur le rover. While this supposition is still in the 'model' area, not the 'data' area, “I think it is likely,” said Lemmon.
Another factor to consider is that “Opportunity has always needed and gotten dust cleanings around this time of the Martian year whether there was a dust storm or not,” said Herman, who did the historic dust-cleaning research that informed the team.
Without any incoming data from the rover on the ground, all the team has had to go on is the orbital HiRISE image taken in September. As to what can actually be determined from that image depends on whom you talk to. While some scientists on the MER team think the rover looks as dusty as its immediate surroundings, others disagree.
The High Resolution Imaging Science Experiment, or HiRISE, is a camera onboard the MRO. The 65-kilogram, $40-million instrument, built under the direction of the University of Arizona's Lunar and Planetary Laboratory by Ball Aerospace & Technologies Corporation, has been producing stunning imagery for more than a decade.
The HiRISE image of Opportunity in Perseverance Valley, which cuts the western rim of Endeavour, was acquired after the dust storm settled down and the Tau was around 1.5. “It shows that the top of the rover looks really bright,” said Arvidson. “But what’s interesting is that the surrounding areas don’t look particularly bright. The area actually doesn’t look much brighter overall pre and post-PEDE. Still, the deck itself looks really bright so it may have trapped more dust than the surrounding areas.”
Initially HiRISE Principal Investigator Alfred McEwen, of the University of Arizona, interpreted that most of the fallout from the storm settled at latitudes higher than Opportunity's coordinates. “Butsince then, we have seen evidence for extensive dust fallout in some equatorial regions as well, such as in Valles Marineris,” he said.
“What is clear is that the dust deposition is very non-uniform, in spite of the fact that the atmospheric dust looked uniform at the peak of the PEDE,” said McEwen, who is a planetary geologist and director of the Planetary Image Research Laboratory (PIRL) at the Lunar and Planetary Laboratory, at the UA.
NASA / JPL-Caltech / University of Arizona
When the sky first cleared
The MER team saw Opportunity for the first time in months when HiRISE, a high-resolution
camera onboard NASA's Mars Reconnaissance Orbiter took this image in late
September 2018, after the sky over Endeavour cleared from the monster global storm
called a planet-encircling dust Event (PEDE). The image shows that the rover is still
hunkered down at her site about halfway down Perseverance Valley, which cuts the
western rim of Endeavour Crater. But to untrained and unknowing eyes, the golf cart
size rover could be mistaken for a boulder. The square highlighting the rover is about
one kilometer (a half-mile) across.
“The west rim of Endeavour Crater looks remarkably similar in color and albedo patterns as an image with similar lighting acquired before the PEDE, with the exception of some small streaks extending south from topographic knobs on the crater floor, McEwen added. “This suggests that some dust was deposited on the nearby crater floor, then removed by surface winds except where protected by topographic obstacles.” [See animated HiRISE gif in this report].
As for what the images tells us about Opportunity? “I don’t think we can say much about the brightness of the rover itself, given the unique photometric geometry of this image compared to previous images of the rover, and the fact that atmospheric opacity was still higher than normal,” McEwen said.
The rover’s solar arrays only occupy a few HiRISE image pixels. “So doing an analysis of how bright the arrays are relative to the surroundings is beset with problems associated with small numbers of samples, and therefore relatively large errors in estimates of the amount of dust on the panels relative to the surroundings,” Arvidson elaborated.
There are, however, plans for HiRISE to take another image. In fact, a shoot had been scheduled in late October as a ride-along with the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) observation that Arvidson, a CRISM co-investigator, proposed. But that was deferred because of troubleshooting a relay problem between MRO and Curiosity.
October proved to be a tough month on Mars. In addition to Oppy’s situation and Curiosity’s memory problem, that troubleshooting required the MRO team to turn off MARCI, CRISM, along with other instruments onboard for a couple of weeks. “Because we’re troubleshooting this relay issue on the MRO, we’ve powered down the instruments temporarily, except for HiRISE, which doesn’t seem to have any of this interference,” said Zurek.“We have had some relay glitches as we were trying to work through with Curiosity, and we’re all getting ready for InSight because it’s not very far away and we’ll be landing shortly after Thanksgiving.”
The objective was to make the environment as quiet as possible as the engineers worked to resolve the anomalous interference with the MRO relay. “We’ll reschedule CRISM for after the InSight landing,” said Zurek.
While you can’t see even see the rover at all in a CRISM pixel, the MER scientists will be able to check out the scene around Opportunity. “With CRISM’s 18-meter per pixel spatial resolution, it is impossible to see the rover,” said Arvidson. “Instead the intent is to estimate the amount of dust that has accumulated on Endeavour Crater’s rim overall as another constraint on what may have accumulated on the rover’s solar arrays.”
NASA / JPL-Caltech / University of Arizona
Now you see the dust, and now you don’t
This gif shows that dust on the floor of Endeavour has been whisked away, indicating
there is wind activity at least on the floor of the crater. Initially HiRISE Principal
Investigator Alfred McEwen, of the University of Arizona, interpreted that most of the
fallout from the storm settled at latitudes higher than Opportunity's coordinates. “But
since then, we have seen evidence for extensive dust fallout in some equatorial regions
as well,” he said.
So the MER team won’t have to wait for InSight to land for HiRISE to take another image. “We will probably try again for the cycle that executes between Nov 11th–24th, said McEwen. “This should be a much better image with clearer air, unless a regional storm kicks up before then, which is common in summer in the southern hemisphere of Mars.”
With NASA’s approval, the MER team is pressing on positively. Work will soon begin on the extended mission plan, beyond 2019. “It’s due in the second week of February,” said Arvidson. “We still have to submit a plan about the science we would do assuming the rover wakes up. We have to do it. It would be weird if on February 1stthe vehicle responds because the dust has been blown off and, despite being 15 years old, it’s survived on its own for nine months or so and us do not have a proposal ready.”
The extended mission would essentially pick up where the PEDE stopped MER in its tracks. Opportunity would continue the science campaign in Perseverance Valley and then drive down into the crater.
First, of course, the robot field geologist has to wake up and the team has to recover her, fix the faults that have been tripped and attend to anything else it would take to put the veteran robot back in the saddle. “Even if we reestablish contact with Opportunity, it will still take a month or more to get the rover under complete Earth control and back to business, and we have to have that in the proposal too,” Arvidson said.
“There is a lot of hope that the vehicle can survive this long and not be communicating with us, because of the dust cover, and then the wind blows off enough dust and we get Opportunity up and running again – that’s the pro side,” Arvidson said. “The con side is – geessh, she’s going on 15 years old. I mean it’s not like we just bought the vehicle. But who knows? We all hope Opportunity comes back.”
Both Opportunity and her twin, Spirit, were “warrantied” for 90-day primary missions on the Martian surface. The expectation was that Mars’ extreme winters and dust storms would take them out. While Spirit, which landed in the harsher region of Gusev Crater, succumbed sometime in 2010, Opportunity has been like the energizer rover ever since, carrying on it seems with the power of two.
In the immediate future, the team will continue the routine of the last month and half. “I don’t suspect there will be much difference in what we do over the next few months,” said Golombek.
NASA hasn't set any deadlines for the mission. The only plan it seems now is that the team will appear before the Mars Program officials at JPL and the powers-that-be at the space agency again for a reassessment sometime in January 2019. “No one has mentioned deadlines recently,” noted Golombek. “Perhaps it’s because of the popularity of the rovers.”
S. Lever
“Until we hear”
MER Mission Manager Scott Lever decided the day after the rover shut down to wait out
the storm to begin growing a beard, and will continue to let it grow “until we hear from
Oppy or give up trying.” The selfie on the left was taken shortly after the team lost
contact. The one on the right was taken on Sep. 26, 2018, after 108 days of silence. the
image on the right was snapped, after coiffing, at the end of October. Like everyone else
on the team, he’s looking forward to getting that ‘phone call’ from Mars.
Grateful and relieved to have NASA’s approval to continue with both active and passive listening, the MER ops team is focusing all eyes and all efforts like a laser beam on the prize. “We will be much happier when finally hear from her,” said Keuneke.
Silent as Oppy was in October, with NASA’s go-ahead, the month of All Hallow’s Eve brought a welcomed kind of fall color to the team. “It’s great that NASA is continuing to use the best available tools for communicating with the rover through January,” said Lemmon. “If there is no signal by then, I'm not sure how we'd get a signal. But between now and then is when we expect the winds, and this is a time when it is still warm at Opportunity’s site.”
Meanwhile, Staab has started to work on what the team calls Hail Mary scenarios, “our last-ditch efforts,” he said. “We’re trying to identify all the scenarios that could have happened, and then which ones we can actually do something about, and how we would actually go about commanding to rule out those scenarios have occurred.” [More on that next issue.]
Time however sets it’s own deadline. Summer will be transitioning into fall in the coming months and fall of course turns to winter. “As we move past summer, solar insolation will be decreasing and temperatures will be decreasing, and unless we get some dust cleaning, dust will continue to accumulate on the solar arrays,” said Callas. “Since the storm, dust has probably continued to settle out of the atmosphere and has probably accumulated even more on the rover, so it is concerning. We just don’t know. The rover hasn’t talked to us, and that is the thing that will tell us what’s going on.”
While the MER team members simply do not know the state of their rover, Opportunity is cherished, and many are choosing to believe, at least for now. That’s not surprising. Belief in themselves and in their rovers put this team into the history books again and again and again, and along the way they succeeded in taking the world on NASA’s first overland expedition of Mars.
These human Mars explorers have bonded with this “Little Miss Perfect” rover in a way that no previous robotic planetary mission ever has – and that is no doubt a key factor in how and why this 90-day mission has gone on for nearly 15 years. “If we could bring Opportunity back just with the strength of our emotions,” said Herman, “she would be back already.”
MER optimism prevails and with luck the mission’s lucky star is still shining. “There is no reason to think yet – we haven’t heard from Opportunity, that means it’s gone,” said Staab. “We’re not even to the point where cleaning season historically begins. So there’s no reason to give up yet. We’re not at that point yet.”
S. Atkinson
Not this day
Author and astronomy outreach educator, Stuart Atkinson, who has been following MER since
the beginning used Google’s Aragorn meme generator to create this graphic. The images are
from the 2003 movie version of J.R.R. Tolkien’s The Lord of the Rings: The Return of the King,
directed by Peter Jackson. Atkinson frequently contributes images to The MER Update and
his own blog that has tracked Oppy’s travels since her journey to Endeavour Crater began. See
his The Road to Endeavour.
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