Meanwhile, Back on Mars, New Dust Storm Data

NASA/JPL-Caltech/SSI's image from the Perseverance Mars rover: a massive dust cloud in Jezero Crater. (June 18, 2021)It’s been a year since I wrote about the Mars 2020 mission.

This seemed like a good time to catch up on what the Perseverance rover and Ingenuity helicopter have been up to in Jezero Crater.

The Ingenuity helicopter has been scouting ahead, giving folks back on Earth up-close aerial views of places the Perseverance rover will be visiting. It was a test vehicle for powered flight on Mars, so it wasn’t loaded with a great many sensors.

The science focus for Mars 2020 is mainly geology. With a focus on learning how habitable Mars used to be. Perseverance has been collecting samples that a later mission will pick up and return to Earth.

But the rover’s MEDA, Mars Environmental Dynamics Analyzer, has also been sending back daily weather reports.1

And in June, 2021, the Perseverance rover observed a dust storm and dust devils in Jezero Crater, sending us pictures from its navigation camera.

We’ve known a little about dust storms on Mars for generations. The 2021 dust storms, near the Perseverance rover, gave scientists their first detailed look at how they form.


Studying Mars, from Ancient Egypt to the Mariner Probes

Giovanni Virginio Schiaparelli's Mars map, showing Martian continents and seas. (1877)
(From Giovanni Schiaparelli, via Meyers Konversationslexikon/Wikimedia Commons, used w/o permission.)
(Giovanni Schiaparelli’s map of Mars. (1877))

We don’t know who first noticed that Mars wasn’t always in the same part of our sky. By the time Senenmut was managing building projects for Hatshepsut, astronomers knew about the planet’s retrograde motion. Egyptian astronomers, that is.

Make that apparent retrograde motion. Earth and Mars orbit the sun at different rates, so it sometimes looks like Mars backs up in our sky.

Fast-forward about 33 centuries. Amateur astronomer Honoré Flaugergues was observing Mars, trying to determine the length of the Martian day. This was in 1809.

He was noting how long it took dark blotches to reappear as Mars turned. His numbers weren’t consistent from one Martian day to another. So he figured that at least some of what he was seeing, or not seeing, were atmospheric phenomena.

These days, some folks say Flaugergues had been observing yellow dust clouds on Mars. Others say he couldn’t have. That’s because his 13.4 meter focal length telescope, with a magnification of 90 times, wasn’t big enough. According to those folks.

Maybe so.

At any rate, Giovanni Schiaparelli noticed that sometimes Mars looked yellower than usual. I gather this was in the 1870s. Eugène Michel Antoniadi said maybe dust clouds caused the Martian color changes.

On the other hand, Schiaparelli had daltonism: a sort of red-green color blindness, and described how his vision and optical properties of his telescope affected his observations.

His daltonism didn’t keep Schiaparelli from noticing and mapping light and dark patches on Mars: which he, along with many other scientists of his era, thought were probably continents and seas.

Sometimes Schiaparelli perceived “canali,” channels, on Mars.2

Seeing may be believing, but it’s not necessarily proof that something’s real.

Schiaparelli and Lowell, Channels and Canals, Craters and Rivers

NASA/JPL/Mariner 4's image, taken during the spacecraft's Martian flyby. One of the craters is now called Mariner. (July 14, 1965)Almost a century after Honoré Flaugergues observed, or didn’t observe, dust clouds while timing the Martian day, Percival Lowell saw canals on Mars.

So did a few other astronomers, although many didn’t. If Schiaparelli’s canali and Lowell’s canals had been real Martian surface features, they were just barely obvious enough to be seen through 20th century Earthbound telescopes.

Then, in 1965, Mariner 4 flew past Mars and sent back pictures. Pictures of craters, more craters, and no trace of either channels or canals. On the ‘up’ side, the images gave us a clear look at the Martian surface.

That’s why, when Mariner 9 arrived and began orbiting Mars in 1971, scientists were looking forward to crisp, clear images of Martian terrain.

What they got were crisp, clear images of a planet-wide dust storm. And the very top of Olympus Mons: the second-highest known mountain in the Solar System. Our planetary system’s tallest known mountain currently is Rheasilvia’s central peak, on Vesta.

A few months later, after the dust settled, Mariner 9 sent back more than 7,000 images: including features that we’ve since confirmed are, or were, river beds.

Well, almost confirmed. A few scientists have pointed out that just because something looks like a channel, with dendritic branching and a fan-shaped delta at its low end, that doesn’t prove that it used to be a river.3

Fair enough. But there’s considerable evidence that water did flow on Mars. Long ago.


Video Shows Wind-Swept Dust Cloud – – –


(From NASA/JPL-Caltech/SSI, used w/o permission.)
(Dust storm on Mars, observed by Perseverance Rover. (June 18, 2021))

Perseverance Views Wind Lifting a Massive Dust Cloud
Images, NASA (June 1, 2022)

“This series of images from a navigation camera aboard NASA’s Perseverance rover shows a gust of wind sweeping dust across the Martian plain beyond the rover’s tracks on June 18, 2021 (the 117th sol, or Martian day, of the mission). The dust cloud in this GIF was estimated to be about 1.5 square miles (4 square kilometers) in size; it was the first such Martian wind-lifted dust cloud of this scale ever captured in images….”

A key phrase here is “of this scale.” Earth-bound Astronomers have been observing Martian dust clouds since the 19th century. Our robot explorers have been sending us pictures for decades.

What’s special about the June 18, 2021, video was that this time we had a robot on site, outfitted with sensors that let scientists study a dust storm as it was happening. Or, rather, study as-it-was-happening data after the Mars rover’s information reached Earth.4

– – – And Dust Devils

Giovanni Virginio Schiaparelli's Mars map, showing Martian continents and seas. (1877)
(From NASA/JPL-Caltech/SSI, used w/o permission.)
(Dust devils in Jezero Crater, spotted by Perseverance rover. (July 20, 2021))

NASA’s Perseverance Studies the Wild Winds of Jezero Crater
News, NASA (June 1, 2022)

“…A paper recently published in Science Advances chronicles the trove of weather phenomena observed in the first 216 Martian days, or sols. The new findings enable scientists to better understand dust processes on Mars and contribute to a body of knowledge that could one day help them predict the dust storms that Mars is famous for – and that pose a threat to future robotic and human explorers.

“‘Every time we land in a new place on Mars, it’s an opportunity to better understand the planet’s weather,’ said the paper’s lead author, Claire Newman of Aeolis Research, a research company focused on planetary atmospheres. She added there may be more exciting weather on the way: ‘We had a regional dust storm right on top of us in January, but we’re still in the middle of dust season, so we’re very likely to see more dust storms.’…”

These scientists figure that aeolian processes — wind moving sand and lifting dust in to the Martian atmosphere — account for many or most changes we’ve been noticing on the planet’s surface and in its atmosphere.

It’s a reasonable assumption, and one that’s been accepted as a possible model for Martian dust storms.

But until last year, scientists didn’t know how dust gets lifted off the surface and into the atmosphere. They’ve done wind tunnel tests here on Earth, which have been useful, but aren’t as valuable as actual on-site observations.

That’s why the June, 2021, dust storm and dust devils are so important in telling us how Martian weather works.

It’s the first time that a probe with the right sensors, in a dusty place, has been looking in the right direction during a windy season.

The Curiosity rover, for example, observed quite a bit of sand motion and many vortices/dust devils: but wasn’t equipped with adequate wind sensors.

The Mars Pathfinder’s rover, Sojourner, carried an MAE: Materials Adherence Experiment. Scientists knew that Mars was a dusty place, but didn’t know how fast dust would accumulate on a rover’s solar cells.

So between July 4, 1997 and August 12, 1997, the MAE let dust gather on a glass plate covering solar cells, rotated the plate to remove the dust, and repeated the cycle.

That told scientists how fast dust accumulated on that part of Mars during that season, but not how or why it does so.

The Insight lander has detected vortices, but so far hasn’t spotted major surface changes.

And the Spirit rover’s solar panels were swept clean of dust a few times. But not when the rover was ‘watching’ the process.5


Gathering Data, Finding New Questions

SA/Roscosmos/CaSSIS, CC BY-SA 3.0 IGO, ESA's Mars Express image: dust storm, an upwelling front of dust clouds near the north polar cap; one of several local small-scale dust storms observed during a particularly intense dust storm season. (April 2018)
(From SA/Roscosmos/CaSSIS, CC BY-SA 3.0 IGO, via Smithsonian, used w/o permission.)
(Martian dust storm, observed near the north polar ice cap. (April 2018))

We’ve coming a long way since the Mariner 4 Martian flyby mission. NASA’s Mars Odyssey and ESA’s Mars Express orbiters have been sending back data since 2001 and 2003.

UAE Space Agency's infographic: illustrating insertion orbit and science orbit. (2021) via BBC NewsAnd the United Arab Emirates Mars Mission, mašrū’ al-Imārāt l-āstikšāf al-Murīkh, مشروع الإمارات لاستكشاف المريخ, has been studying daily and seasonal weather cycles since last year.

The UAE’s Hope orbiter as given scientists enough data for at least five research papers that I know of.

Meanwhile, data from NASA’s Mars Global Surveyor, Mars Science Laboratory’s Curiosity rover, and InSight missions show that heat from the sun makes for strong daily and seasonal changes of Mars.

And this helps explain the planet’s seasonal dust storms. Probably.6

I get the impression that, although we’re gathering a great deal of information about Martian weather and the Martian climate — we’re finding new questions almost as fast as we’re getting answers.

Martian Ice Ages

NASA/JPL/Brown University's illustration of Mars during a possible ice age, some 2,400,000 to 400,000 years ago. (2003)
(From NASA/JPL/Brown University, used w/o permission.)
(Mars may have been in an ice age, between 2.4 million and 400,000 years back.)

For example, we’ve been learning that the Martian climate has changed — a lot — since the planet formed.

That’s why the Mars 2020 mission is looking for evidence of past life on Mars. There’s almost no chance that anything lives there now, but Earth’s neighbor wasn’t always the desiccated wasteland it is today.

There’s even evidence of a Martian ice age, from maybe 2,400,000 to 400,000 years back. Maybe.7

There’s a great deal more to say about Martian weather, climate, seasons and cycles.

But that will have to wait. Thanks partly to a summer cold I’ve been having, and partly to a particularly annoying Internet service outage, I’ve had ample opportunity to practice patience this week. And that’s another topic.

More Martian monographs by me:

And why “…I see no problem with seeking truth that we find in this universe and seeking truth’s source….”


1 Mars 2020 mission, briefly:

2 Eyes on Mars:

3 Mars; getting a closer look:

4 Measuring Martian winds:

5 Dusty rovers and science:

6 Studying Martian weather and climate:

7 Lost oceans and a changing world:

About Brian H. Gill

I was born in 1951. I'm a husband, father and grandfather. One of the kids graduated from college in December, 2008, and is helping her husband run businesses and raise my granddaughter; another is a cartoonist and artist; #3 daughter is a writer; my son is developing a digital game with #3 and #1 daughters. I'm also a writer and artist.
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