Curiosity Catches Two Eclipses

The cameras on NASA’s Curiosity rover usually look down at the rocks on Mars, divining clues in the minerals of what the planet was like billions of years ago.

Sometimes though, the rover also looks up, and in March it spotted two eclipses (eclipsi?).

Eclipses on Mars are not as total as those on Earth where the moon completely blots out the sun. The two moons of Mars are tiny. Phobos is 7 miles wide while Deimos is even tinier, just 1.5 miles in diameter. They only partially block the sun when they pass in front of it.

The camera on Curiosity’s mast is equipped with solar filters that allow it to look directly at the sun and photograph eclipses. On March 17, Curiosity observed Demios eclipsing the sun. Nine days later, it also spotted Phobos passing in front.

The observations by Curiosity, and by earlier NASA Mars rovers, Spirit and Opportunity, enable more precise pinpointing of the moons’ orbits, which are jostled around by the gravity of Mars, Jupiter, and even each other.

Although Phobos and Deimos are small, the details of their formation are of considerable scientific interest. Japan’s space agency plans to send a spacecraft to the two moons within the next decade. The Mars Moon Exploration probe, or MMX, will collect samples and return them to Earth for study. A panel of scientific experts recently approved the sample-return phase of the mission.

Passing Gas on Mars

Methane gas is periodically detected in the atmosphere of Mars. This was once considered implausible and perplexing, but it is now widely accepted by planetary scientists. Why the methane is there is still a mystery. It could point to present-day Martian microbes living in the rocks below the surface.

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Scientists working with the ESA’s Mars Express orbiter reported that in the summer of 2013, the spacecraft detected methane within Gale Crater, a 96-mile-wide depression near the Martian equator.

In the same summer of 2013, NASA’s Curiosity rover also measured a marked rise of methane in the air that lasted over two months.

The presence of methane is significant because the gas decays quickly. Calculations indicate that sunlight and chemical reactions in the thin Martian atmosphere would break up the molecules within a few hundred years, so any methane detected must have been created recently.

It could have been created by a geological process known as serpentinization, which requires both heat and liquid water. Or it could be a product of life, specifically methanogens, microbes that release methane as a waste product. Methanogens thrive in places lacking oxygen, such as rocks deep underground and the digestive tracts of animals.

Even if the source of the methane turns out to be geological, the hydrothermal systems that produce the emissions would still be prime locations to search for signs of life.

A newer European Mars spacecraft, the Trace Gas Orbiter, which has a more sophisticated methane detector, has been in orbit since 2017, but no results have been reported as of yet.

Tremors on Mars

Since NASA’s InSight lander, um landed on Mars at the end of last year, the plucky surface probe has spent months getting carefully situated so that its special seismometer could listen for “marsquakes” a neologism for earthquakes that occur on Mars, rather than Earth, as you probably guessed.

Observations of marsquakes will help determine just what’s going on inside of Mars, and to what extent it is still a geologically active world. We know Mars was very geologically active in the past; it has the tallest mountain of any planet in the solar system.

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While InSight hasn’t heard mars-shaking marsquakes yet, Scientists have revealed that the lander’s instrument has detected a different kind of rumbling known as microseisms. They are the first of their kind to be detected on another planet.

The new noises are caused by low-frequency pressure waves from atmospheric winds. On Earth, microseisms are caused by the ocean, storms and tides. Researchers working on InSight hope to hear a real marsquake within one month.

InSight’s other instruments have been providing scientists with troves of data. Indeed, since mid-February, InSight has issuing weather reports from Mars.

Ultimately, InSight’s science will help contribute to an overall picture of the history of the solar system, and how Mars, Earth and the other planets formed and evolved. The Auxiliary Payload Subsystem (APSS) lets InSight provide more frequent weather information than any previous mission to Mars.

InSight’s science will help contribute to an overall picture of the history of the solar system, and how Mars, Earth, and the other planets formed and evolved.

Old Scars on Mars

Mars is a cold, dry place, but it may not always have been. Recent studies increasingly indicate that the planet once had a thicker, denser atmosphere that was able to lock in far more warmth, and therefore facilitate and support the flow of liquid water on the surface.

While this is no longer the case, planetary researchers have seen clear signs of past water activity across the Martian surface. New images from ESA’s Mars Express orbiter show one such region: a branching system of trenches and valleys in the southern highlands of Mars.

The southern highlands are some of the oldest and most heavily cratered parts of the planet, with many signs of ancient water. The topography of this region suggests that water flowed downhill from the north to the south, carving out valleys up to 1.2 miles (2 km) across and 656 feet (200 m) deep as it did so.

It is thought that climate change took place on Mars 3.7 to 3.8 billion years ago, when environmental conditions changed from a somewhat neutral, potentially life-sustaining and humid environment to a much drier, colder environment that is hostile to life.

One of the reasons why Mars lost its atmosphere was the loss of its magnetic field, which was active during its first 500 million years.

As the magnetic field grew weaker the solar wind was able to gradually split the molecules in the atmosphere. The resultant ions were then lost to space. As a result, and also due to declining volcanism, the atmosphere became thinner. Below a certain atmospheric pressure, water can no longer remain liquid on the surface of a planet, it can only remain as ice or gas.

Mars is also only about half the mass of Earth, so its gravitational force is barely sufficient to bind atmospheric molecules to it and the lack of precipitation on Mars collapsed the water cycle.

While it is unclear where all of this water came from originally (precipitation, groundwater, melting glaciers) all of this required a far warmer and more watery past for Mars.

R.I.P. Opportunity 2004-2019

On Wednesday, NASA that the Mars land rover Opportunity has died after 15 years. The six-wheeled vehicle’s death is being attributed to a severe dust storm.

From the AP:

“Flight controllers tried numerous times to make contact, and sent one final series of recovery commands Tuesday night, along with one last wake-up song, Billie Holiday’s ‘I’ll Be Seeing You,’ in a somber exercise that brought tears to team members’ eyes. There was no response from space, only silence.

Thomas Zurbuchen, head of NASA’s science missions, broke the news to the Opportunity team at what amounted to a wake at the space agency’s Jet Propulsion Laboratory in Pasadena, California, announcing the demise of ‘our beloved Opportunity.’

Given the silence from space, ‘it is therefore that I’m standing here with a sense of deep appreciation and gratitude that I declare the Opportunity mission as complete,’ Zurbruchen told a packed auditorium. ‘It’s an emotional time.’”

Opportunity was one of two rovers that landed on the Mars in 2004. The other rover, Spirit, didn’t last as long as Opportunity. Communications with Spirit were lost after it was caught in a sand trap. Nonetheless, both vehicles exceeded NASA’s expectations.

When Opportunity and Spirit landed on Mars in 2004, the mission was only meant to last 90 days. But the vehicles, which were sent to different parts of the planet, proved to be surprisingly durable. Communication with Opportunity was finally lost in June 2018, and as rugged as the vehicle was, it was no match for the severe dust storm it encountered.

Opportunity explored an area of Mars called Perseverance Valley when it encountered the dust storm, which was so harsh that it darkened the sky for months and prevented sunlight from reaching Opportunity’s solar panels.

Opportunity was the fifth of eight NASA space vehicles that have successfully landed on Mars. Two of them are still working: Curiosity (which landed in 2012) and InSight (which landed recently).