Mars is a dusty devil (Image: JPL-Caltech/UA/NASA)

Mars dust is dangerous to human health and could severely hamper proposed missions to send people to the Red Planet. So say space-health and life-support researchers who met this week to mull over the possibility of sending a crewed mission to Mars by 2030.

Laboratory studies had suggested that Mars dust might be a health hazard because it contains fine-grained silicate minerals, which are common on Mars. If breathed in, the silicate dust would react with water in the lungs to create damaging chemicals.

Recent robotic missions suggest that the outlook for a crewed mission may be even worse. Delegates to the Humans 2 Mars Summit (H2M) in Washington DC, an effort to chart and overcome the challenges of getting humans to Mars within the next two decades, yesterday heard the latest evidence of the dangers of Martian dust.


Richard Williams, NASA’s chief health and medical officer, pointed out at the meeting that perchlorates, which are known to harm the thyroid gland, increasingly look to be widespread on Mars.

Baked for analysis

Perchlorates were first detected by NASA’s Phoenix lander in 2008 near the Martian north pole. More recently, there was a possible detection by NASA’s Curiosity rover, which landed in August 2012 and is now exploring Gale crater, near Mars’s equator. Last December, Curiosity’s Sample Analysis at Mars (SAM) instrument baked up a scoop of soil, taken from a site called Rocknest, to analyse the dust’s composition.

“We believe that there could be perchlorates in the Rocknest dust sample,” says Paul Mahaffy, principal investigator for SAM. “Since dust blows all over Mars, this certainly should be considered along with other human health impacts.”

That’s not all. In the past few months Curiosity has found veins of a mineral, most likely gypsum – and that is also worrisome, says Grant Anderson, co-founder of Paragon Space Development, a company based in Tucson, Arizona.

“Gypsum is not really toxic per se, but if you breathe it in you do start to see a build-up in the lungs that’s equivalent to the coal-dust lung experienced by miners. That leads to breakdowns in lung capacity,” says Anderson. The US National Institute for Occupational Safety and Health classifies gypsum dust as a nuisance particulate that can irritate the eyes, skin and respiratory system, and sets recommended exposure limits.

Sticky nuisance

But with limited atmospheric oxygen as well as dangerous radiation to contend with, astronauts on Mars won’t be going out and breathing in dust directly. They will have to remain inside special habitats, donning spacesuits if they venture out. So could this dangerous stuff still wend its way into their bodies?

The problem starts with the spacesuits, which Martian dust will stick to persistently, says Anderson. “That’s one thing they learned from the Apollo missions on the moon,” he adds.

Those missions showed that lunar soil has been ground into fine, sharp-edged grains that cling to just about everything, thanks to bombardment from micrometeorites and charged particles from the sun. Although Martian dust has been somewhat protected by a thin atmosphere, it has been blowing around for 3.5 billion years, and that has worn down the particles into very small, round grains. The grains aren’t sharp, but constant roiling around the planet has probably given Mars dust a significant static charge, says Anderson, which could make it sticky.

The fear is that since the dust cannot easily be cleaned from suits, it will get into astronauts’ living quarters, even if they return via an airlock – an intermediate space between their quarters and the low-pressure, CO 2 -rich environment of Mars. “What you’re going to want to do is pump out the CO 2 and then let in air,” explains Anderson. “That creates eddy currents, which creates flow. You’ve got such fine dust on Mars that you won’t be able to keep it down, and the person will be breathing it in.”

Robotic answers

Dust wafting inside the astronauts’ quarters might also clog air filters, water purifiers and other critical instruments, warned Greg Gentry, an engineer at Boeing in Houston, Texas, and the technical lead for the Environmental Control and Life Support System on the International Space Station. But for now no one really knows how Mars dust will affect the equipment people will need to survive on the planet. “Dust is a problem because no one knows what it is going to do on Mars,” says Anderson.

The good news is that robotic missions such as Curiosity could help provide vital answers. “The Apollo programme spent $17 million trying to solve their lunar dust problems, and I’m not sure they made much progress, because they had to do the tests on Earth,” says Anderson. “For Mars, the precursor robotic missions should all have some way to test how dust is going to kill you.”

So far, such practical concerns have done little to curb enthusiasm for a human Mars mission. Two weeks ago, the private Mars One venture started taking applications for its one-way trip to the Red Planet. On 7 May, the company announced that it has received 78,000 applicants, and counting. “This is turning out to be the most desired job in history,” Mars One co-founder Bas Lansdorp said in a statement.