A massive dust storm on Mars that threatened NASA’s lander has finally subsided.
At the end of September, the NASA Mars Reconnaissance Orbiter sounded the alarm for missions studying the Red Planet: a dust storm was brewing. Such storms have a grim reputation among ground missions since a planet-wide storm ended the 2018 solar-powered Opportunity rover mission. And now NASA has another solar powered robot on the surface to worry about: its InSight lander. For several weeks, the storm left InSight alone, but by early October, dust covered the sky above it, and spacecraft personnel became worried that their mission would suddenly end.
“It is now clear that while the end of the InSight mission is still around the corner, the lander is going through a major storm and dust is starting to fall from the sky,” Claire Newman, atmospheric scientist at Aeolis Research, who makes weather observations from the surface of Mars. spacecraft, Space.com reported.
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Scientists are still working to understand the nuances of weather on the Red Planet, and dust storms in particular, Newman said. Small localized dust storms can occur year-round, but larger storms become more frequent as summer ends in the southern hemisphere, so a storm like the one that threatened InSight is within the normal range.
“This is an event that we often see at this time of year,” Newman said. “We were hoping it would just be regional. It looks like it’s pretty big in its own right.”
Storms follow a seasonal rhythm because they are caused by a heat imbalance that kicks dust from the surface into the thin Martian atmosphere. There he starts a vicious circle. “You kick up dust, the dust heats up, which causes those temperature gradients to decrease, so locally you tend to have stronger winds, and then they tend to kick up more dust,” Newman said.
Orbiters can detect brewing storms in images and temperature data, but missions on the surface can also identify storms, even distant ones, because the dust makes the typical daily Martian atmospheric pressure cycle more dramatic. For example, the Perseverance rover detected these pressure changes in the early days of the storm, even when there was no dust in the sky above Jezero Crater.
“This is a global response to something that can only happen on a third of the planet or less,” Newman said.
This is different from a global storm that fills the atmosphere around the entire planet from east to west with dust. These storms can form every few years because it’s hard to stop the feedback loop on Mars that causes dust in the atmosphere.
“There’s no global dust storm on Earth, and that’s partly because the thick atmosphere kind of prevents these really strong feedbacks,” Newman said. “But it’s also because you have oceans, you have water and rainfall, and that pulls dust out of the atmosphere, whereas on Mars you don’t have anything to slow dust down.”
Although the recent storm was a major regional event, it failed to cover the entire planet. The delay may be due to the fact that most of the surface winds on Mars at this time of year blow from the north, and this storm began from the south. So while the upper atmosphere in the northern hemisphere (where Perseverance is hosted) became somewhat dusty, the storm itself may have struggled to gain a foothold on the surface and spread north.
“Perhaps the time of year it happens and the background circulation made it difficult for it to expand and become global,” Newman said. “It will have a hard time expanding northward and into the northern hemisphere at low levels because the background flow is moving in the wrong direction.”
It’s unlikely, though not impossible, that Mars will see another major dust storm this year, Newman said. “Most likely, the season of big dust storms is coming to an end,” she said. “You can never say never to Mars.”
The recent storm is the second major storm this Earth year, after a storm near the Perseverance rover’s outpost in Jezero Crater. Newman noted that this storm came unusually early this season and was particularly intriguing.
“This was the first time we were able to make detailed observations in a place where dust was actively rising during the storm,” she said. “Actually, we were in the place where the source of the storm was.”
Previously, other ground missions in places where dust rose from the surface had to squat, not being able to observe this phenomenon. However, Perseverance’s January observations didn’t quite go as planned: The storm wind was strong enough and carrying enough debris to damage one of the rover’s wind sensors, making it difficult for the rover to take measurements.
Luckily there was more to see. “When that January storm hit us, we saw a significant increase in the rise of dust and even dust whirlwinds,” Newman said. “We also saw a lot of movement on the surface; we saw mostly small ripples that moved.”
The global map of Mars shows a powerful dust storm in the southern hemisphere, marked in beige on September 29, 2022. (Image credit: NASA/JPL-Caltech/MSSS)
InSight is particularly vulnerable to dust storms due to its reliance on solar panels, but the nuclear-powered Curiosity and Perseverance rovers still benefit from knowing that a storm is coming.
For example, scientists can speed up activities that would be easier to do before a storm hits, or delay activities that might be more dangerous in high winds. And, of course, they can schedule additional observations of the storm itself. “Even if you don’t have to worry about dust, you still want your ducks to be in the weather monitoring row,” Newman said.
And observations of the weather, especially on the surface, are critical for scientists working to create models of dust storms that better match reality.
“There is no model that can really mimic the life cycle of a dust storm really well,” Newman said, unless scientists load them with a lot of specific specifications. “All models diverge from reality at some point.”
These models are vital to the work she and other atmospheric scientists are doing, using site-specific surface observations in addition to orbital data, to piece together the dynamics of Mars on a much larger scale than any spacecraft can observe.
“We’re trying to figure out where we are,” she said of ground-based weather stations. “We are trying to understand the entire planet by understanding where we are. And we are also trying to understand the past by understanding the present.”
Email Meghan Bartels at mbartels@ or follow her on Twitter @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.