Space Sunday: Mars roundup

via Associated Press

NASA’s INterior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) lander, launched in March 2018, is due to land on Mars on November 26th, 2018. Managed by NASA’s Jet Propulsion Laboratory, the mission is intended to study the internal structure of the planet, and in doing so it could bring new understanding of the Solar System’s terrestrial planets — Mercury, Venus, Earth, Mars and the Moon.

The lander is based on the design used for NASA’s Mars Phoenix lander, which successfully arrived on Mars in 2008, using circular solar arrays to generate power for its systems and instruments. As with the Phoenix Lander, InSight is designed to operate for a Martian year once on the surface of Mars, with an initial primary mission period of 90 days.

As a static lander, InSight will use a range of instruments to study the deep interior of Mars. Two of the principle instruments in this investigation are the Seismic Experiment for Interior Structure (SEIS) and HP3, the Heat Flow and Physical Properties Package, both of which will be placed in direct contact with the surface of Mars after touch-down.

An artist’s impression of InSight on Mars, showing the SEIS package deployed. Credit: NASA / JPL

Developed by the French Space Agency (CNES), with the participation of the Institut de Physique du Globe de Paris (IPGP), the Swiss Federal Institute of Technology (ETH), the Max Planck Institute for Solar System Research (MPS), Imperial College, Institut supérieur de l’aéronautique et de l’espace (ISAE) and JPL, SEIS is a sensitive instrument designed to do the work of an entire network of seismographs here on Earth.

It will measure seismic waves from marsquakes and meteorite strikes as they move through the planet. The speed of those waves changes depending on the material they’re travelling through, helping scientists deduce what the planet’s interior is made of. Seismic waves come in a surprising number of flavours; some vibrate across a planet’s surface, while others ricochet off its centre and they also move at different speeds. Seismologists can use each type as a tool to triangulate where and when a seismic event has happened.

Such is the sensitivity of SEIS, it can sit in one place and listen to the entire planet and detect vibrations smaller than the width of a hydrogen atom. It will be the first seismometer to be directly placed on the surface of Mars, where it will be thousands of times more accurate than seismometers that sat atop the Viking landers.

Artist’s illustration of InSight’s Seismic Experiment for Interior Structure (SEIS) instrument on the Red Planet’s surface. Credit: NASA TV/JPL

Also, because of the instrument’s sensitivity, SEIS will be protected from the local weather by a protective shell and skirt, both of which will stop local wind interfering with the instrument. In addition, it will be supported by a suite of meteorological tools to characterise atmospheric disturbances that might affect its readings.

HP3 has been provided by the German Aerospace Centre (DLR). It is a self-penetrating heat flow probe,  more popularly referred to as a “self-hammering nail” with the nickname of “the mole”. Once deployed on the surface of Mars, it will burrow 5 m (16 ft) below the Martian surface while trailing a tether with embedded heat sensors every 10 cm (3.9 in) to measure how efficiently heat flows through Mars’ core, revealing unique information about the planet’s interior and how it has evolved over time.

The “self-hammering nail” description comes from the spike, or “mole” at the end of the tether. A mechanism within it  will allow it to propel itself into the Martian regolith and down through the rock beneath it.

Diagram of HP3, showing the deployment system, the “mole” and tether. Credit: DLR

Once fully deployed, HP3 will be able to detect heat trapped inside Mars since the planet first formed. That heat shaped the surface with volcanoes, mountain ranges and valleys. It may even have determined where rivers ran early in Mars’ history.

On arrival at Mars, InSight will enter the planet’s atmosphere and land on Elysium Planitia, around 600 km (370 mi) from where the Curiosity rover is operating in Gale Crater. I’ll have more on the mission around the time InSight makes its landing on Mars.

Enough Oxygen to Support (Microbial) Life

When it comes to life on Mar, most of the focus has been on the amount of water that may once have been present on the planet – and how much of it has survived in the form of ice. However, there is another potential ingredient that has the potential to assist life – oxygen. A constituent part of water, how much oxygen might have existed on Mars – or might still exist – has tended to escape attention.

This is because in its free state, oxygen makes up a very tiny percentage of Mars’ atmosphere, which is primarily composed of carbon dioxide and methane. However, and perhaps conversely, geochemical evidence from Martian meteorites and manganese-rich rocks on its surface have shown a high degree of oxidation. This suggests oxygen did play a role in the chemical weathering of the Martian crust.

A new study indicates there could be extensive subsurface deposits of oxygen on Mars that may have allowed microbial life to arise. Credit: unknown

Now a new study, suggests that Mars may have enough oxygen locked away beneath its surface to support aerobic organisms, giving a boost to the theory that life microbial could still exist on Mars. It uses two lots of information gathered by vehicles currently operating on Mars and in orbit around it. The first being chemical evidence gathered by the Chemistry and Mineralogy (CheMin) instrument, on NASA’s Curiosity rover, which confirmed the high-levels of oxidation in samples of Martian rock. The second being evidence obtained by the Mars Express’ Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument, which indicated the presence of water beneath Mars’ southern polar region.

Using these two sources, a science team led by Vlada Stamenkovic, an Earth and planetary scientist and a theoretical physicist at NASA’s Jet Propulsion Laboratory (JPL), carried out a 3-part examination of the potential for oxygen on Mars. They did so by using the data to develop a comprehensive model that both allowed them to firstly identify those regions most likely to sustain high levels of oxygen solubility (the transfer of oxygen from the surface-touching atmosphere to the rock below) and then determine how the distribution of aerobic environments evolved over the past 20 million years, and how they might change in the next 10 million.

From this the researchers determined two things. Firstly,  even in the worst case scenarios, there was enough oxygen in Martian rocks and subsurface reservoirs to support aerobic (oxygen breathing) microbial organisms. Secondly, most of the subsurface environments on Mars exceeded the oxygen levels required for aerobic respiration by up to 6 orders of magnitude. To put this in perspective, it indicates that subsurface environments on Mars have equitable oxygen levels to those found in the Earth’s oceans today. This points to two potentials:

  • That life could still exist in underground salt water deposits and offer an explanation for the formation of highly oxidised rocks.
  • There could be multiple locations around the polar regions where much higher concentrations of oxygen existed, which would be sufficient to support the existence of more complex multi-cellular organisms like sponges.

All of this helps to further reveal From all this, what begins to emerge is a picture of how life on Mars could have migrated underground, rather than simply disappearing. As the atmosphere was slowly stripped away and the surface cooled, water began to freeze and travel into the ground and subsurface caches, where enough oxygen was present to support aerobic organisms independent of photosynthesis.

The study may influence how and where missions such as the Mars 2020 rover might be sent to in the search for evidence of past life. Credit: NASA/JPL

The study also indicates how life on Mars might have evolved life under different conditions to those of prehistoric Earth. Here, anaerobic organisms arose in a noxious environment and used photosynthesis to produce oxygen (making the atmosphere suitable for aerobic organisms). On Mars, aerobic organisms could have sourced oxygen through rocks and water to sustain themselves in a cold environment away from the Sun. Further, the study offers potential new avenues for understanding how life may have arisen elsewhere in the solar system.

However, while it present the possibility that life could have arisen in subsurface caches on Mars, it does not conclusively prove that such life is still present on the planet today.

No, It’s Not and Eruption

A long, thin cloud on Mars, elongated enough so as at times it can be seen through Earth-based telescopes, has caused a stir on the less well-informed parts of the web, with claims that it is signs of a volcanic eruption on the planet; claims born of the fact that the cloud appears to trail away from the location of Arsia Mons, the southernmost of the three great Tharsis bulge volcanoes.

The leeward trailing plume of a 1,600 km (1,000 mile) water ice cloud extending away from the 110 km (72 mi) diameter summit crater of Arsia Mons. Also visible in this image are the blemishes of the other two Tharsis Bulge volcanoes of Pavonis Mons and Ascraeus Mons lying above Arsia, and mighty Olympus Mons lying on the terminator to the left of the image. Credit: ESA / GCP / UPV / EHU Bilbao

Seen in images recorded by Europe’s Mars Express orbiter, the plume stretches for around 1,600 km (1,000 miles) to the west of the volcano, which sits close to the planet’s equator, but it isn’t directly related to Arsia Mons or to any form of volcanic activity. Rather, it is a seasonally recurrent high altitude water ice cloud, and it is not entirely unknown phenomena.

In fact, Mars Express has been observing the cloud since mid-September, although it wasn’t until around mid-October that incorrect claims that the volcano was erupting started to surface. It’s actually the fourth such cloud the orbiter has observed, the other three occasions being in 2009, 2012 and 2015. It has also been and it has also been seen by NASA’s orbiters around Mars. Such is the frequency with which it has been seen, scientists are confident that it is the product of local season variances on Mars.

Image captured by Mars Express on September 17th, 2018, as the cloud was forming over Arsia Mons. Again, Pavonis Mons (centre) and Ascraeus Mons (top) can also be seen. Credit: ESA / CNES / CNRS / IAS

Normally, the summit of Arsia Mons, rising 20 km (12.5 mi) above the average level of the surrounding plains, tends to be obscured by cloud. However, in the period leading up to the time of the northern hemisphere winter solstice on Mars (which occurs in October), the airflow around the Tharsis region closest to the equator – which includes Arsia Mons – changes. For the most part, the clouds around the volcano are dissipated by these changes; but occasionally, the conditions cause the Martian atmosphere to break and flow around Arsia Mons in such a way to generate a large-scale and persistent type of water ice cloud scientists refer to as an orographic or lee cloud.

A critical factor in forming this kind of cloud on Mars is the amount of dust suspended in the upper atmosphere, itself a product of the seasonal dust storms on the planet. As we know, Mars has just experienced a major dust storm of global proportions that has likely left a lot of dust still suspended at high altitude. Given the relationship between these clouds and dust suspended in the atmosphere, it is hoped the study of this cloud and others like it could provide important information on the influence dust has on atmospheric changes throughout the Martian year.

Rover Update

Opportunity: October 28th marks the 140 day since communications with the Mars Exploration Rover (MER) Opportunity as a result of a globe-spanning dust storm on Mars. The mid-point of the 45-day period dedicated to trying to recover contact with the rover, but no success has been achieved thus far. It is believed Opportunity has likely experienced one of three failures: a low-power fault; a mission clock fault or an up-loss timer fault. The latter two of these would mean the rover doesn’t known when it can communicate with Earth, either directly via NASA’s Deep Space Network (DSN) Radio science receivers, or via any of the orbiting vehicles circling Mars. To try to counter any clock fault, the mission team have commanded DSN to perform “sweep and beeps” throughout the daily DSN passes to try to let Opportunity know Earth can hear it, and encourage it to start communicating.

Curiosity: at the start  of October, the Curiosity mission team commanded the rover two switch computing operations between its two “brains”. Like many of NASA’s vehicles, Curiosity has two central computer system, referred to as Side A and Side B. It has been operating using Side B since its 200th day on Mars, having switched to it after Side A developed serious memory fault that came close to finishing the mission with the rover unable to act on commands from Earth. The decision to switch back to Side A – which since its initial failure has received a software update to prevent it using the faulty memory module – was made after engineers noticed Curiosity was unable to store data it its long-term memory or save its event records – a crucial part of diagnosing issues that may occur with the rover – when using Side B. The switch  has left the rover in a reduced operational state as engineers attempt to diagnose and resolve the Side B issues.

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