NASA has announced it will undertake a 45-day campaign to try to re-establish contact with its long-lived Mars Exploration Rover (MER) Opportunity. in the wake of contact being lost was a globe-spanning dust storm started to grip Mars in June 2018.
After running its course for almost three months, the storm is now abating, and whilst not the biggest storm seen on Mars since “Oppy” arrived there it the start of 2004, it is one of the most intense in terms of the amount of dust thrown up into the Martian atmosphere.
Contact with the rover was lost in early June 2018. With sunlight barely able to penetrate the dust in the air, it is thought the rover went into hibernation to conserve battery power – terminating contact with Earth in the process.
The attempt to re-establish communications will commence once the tau in the region where “Oppy” is located has dropped below 1.5. Tau is the term used to measure the opaqueness of the dust in the Martian atmosphere, and it is usually around 0.5. Opportunity requires a tau of below 2.0 to avoid triggering its sleep mode, and by early June the value had reached 10.8 – making this dust storm the densest the rover has ever encountered during its fourteen years on Mars.
As a solar-powered vehicle, there are a number of risks Opportunity faces during a long duration dust storm. The first is that as the batteries cannot be charged, they could run out of sufficient power required to keep the rover’s sensitive electronics warm – although this is partially mitigated by the fact that during a storm like this, the heat normally radiated away by the planet gets trapped in the dusty atmosphere, raising the ambient temperature and thus offsetting the amount of power the rover needs to use to keep itself warm.
To other points of concern with the rover are the potential for a clock failure, or what is called an “uploss” recovery being triggered. Opportunity’s on-board clock allows the rover to track when an orbiting satellite – vital for relaying signals from the rover to Earth – is above the local horizon, allowing Opportunity to make contact with Mission Control. If it has failed or now has an incorrect reading as a result of power fluctuations, “Oppy” might not be easily able to establish contact with Earth by itself. An “uploss” recovery is triggered when the rover has failed to establish contact with Earth for an extended period. There is a concern that if the rover didn’t enter its hibernation state correctly, the lack of any communications might have triggered this mode, forcing the rover to continuously re-try different methods to receive a signal from Earth, using up its power reserves.
The 45-day campaign will be a pro-active attempt to re-establish contact with “Oppy” from Earth by sending commands out to it. However, if there is no response from the rover, a grim warning was given in the announcement:
If we do not hear back after 45 days, the team will be forced to conclude that the Sun-blocking dust and the Martian cold have conspired to cause some type of fault from which the rover will more than likely not recover. At that point, our active phase of reaching out to Opportunity will be at an end.
– John Callas, Opportunity project manager, NASA Jet Propulsion Laboratory
This has drawn some sharp criticism from former members of the MER team, particularly those who worked with Opportunity. They point out that when communications were lost with the other MER vehicle, Spirit, in 2010, NASA spent 10 months trying to re-establish contact. In response to the criticism, NASA state that the 45-day period has been dictated by the decreasing amount of sunlight the rover is receiving as winter approaches, requiring the rover to start conserving power once more, but they will continue to listen for any attempts by the rover to re-establish communications after 45 day campaign has come to an end – they just won’t continue to try to make the connection pro-actively.
Even if communications are re-established, it doesn’t necessarily mean “Oppy” is out of danger; there is a chance that the storm has caused the rover to use its batteries for so long without charge, then may not longer have the capacity to charge correctly or to efficiently retaining their charge – either of which could severely impact further operations for the rover, and require careful assessment.
Soyuz Pressure Leak at the ISS
A Soyuz vehicle suffered a minor loss of cabin pressure whilst docked at the International Space Station (ISS), causing a bit of a fuss in some sectors of the media.
At around 19:00 Eastern Standard Time on August 29th, 2018, ground controllers noted a loss of atmospheric pressure in the orbital module of a Soyuz MS-08 docked to the station. While some media outlets reported the ISS crew “scrambled” to locate and patch the source of the pressure loss, the drop was so slight mission controllers decided to allow the 6-man crew to continue their sleep period aboard the station, and did not inform them of the issue until they were woken up at their scheduled time.
The leak was ultimately traced to a 2mm hole through the skin of the Soyuz module. A temporary fix was made using tape while the crew awaited instructions from Earth on how best to affect a more permanent repair. This actually highlighted a difference in approach between American astronauts and engineers and their Russian counterparts in handling situations.
The Americans – including Expedition 56 Commander Drew Feustel – were keen to explore and test options on Earth before determining on a curse of action out of concern that if options were not tested, then a repair could result in additional damage to the Soyuz. Russian engineers, however, proposed just the one approach to making the repair, and ordered the two Russian cosmonauts on the ISS – Oleg Artemyev and Sergei Prokopyev – to make the repair without any Earth-based testing, handling the situation entirely in Russian and using an interpreter to keep NASA personnel appraised of progress.
After completing the work, Artemyev and Prokopyev reported bubbles forming in the patch, but were instructed to leave it in place to harden over 24 hours. At the time of writing, the path appears to be holding, with no further leaks reported. The damaged Soyuz had been scheduled to make a return to Earth in December 2018 (each vehicle generally spending around 6 months berthed at the ISS alongside another Soyuz so they can be used as “lifeboats” by a station crew should they have to abandon the station for any reason), but as a result of the incident, mission controllers are contemplating using the vehicle in October, when three of the current ISS crew are due to return to Earth.
As the leak occurred in the Soyuz orbital module, it does not pose a threat to a crew: the module is only used during the time a Soyuz is en route to the ISS to give the crew a little more space. On a flight back to Earth the module is jettisoned along with the power and propulsion module, leaving the crew to return in the “mid-ships” Earth return capsule.
The cause of the leak is still being investigated, but suggestions are that it may have been a MMOD – a MicroMeteoroid (tiny piece of orbiting rock weighing less than a gramme but travelling at high-speed) or a piece of Orbital Debris (tiny fragment of debris from a space mission). Such strikes have occurred with the ISS in the past, but if this is the cause of the Soyuz leak, it will be the first time such a strike has directly resulted in a loss of atmospheric pressure either aboard the station or a vehicle docked with it, something that will add to concerns as to the amount of natural and human-made debris circling Earth.
Continue reading “Space Sunday: saving Oppy, ISS leaks, and humans to Mars”
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