Tag Archives: dust

A dust-off broom for Mars

Romanian engineers have developed a small plasma jet capable of blowing Martian dust from solar panels and other equipment that can be used by future missions.

The “plasma broom” solution developed by Ticoş and colleagues uses bursts of plasma jet produced by a simple plasma accelerator. When a large current is passed through two electrode plates separated by a field of rarefied gas, the voltage difference between the two electrodes ionizes the gas, creating the plasma. In the broom, this is done with a coaxial gun – the two metal electrodes are arranged as an inner rod within a hollow cylindrical shell. The discharge current flowing through the central rod electrode produces a magnetic field, which, together with the electric field, exerts a Lorentz force on the ionized gas that expels it. “The trick is that you need a quite high current in order to produce a reasonable magnetic field and this can be achieved more conveniently in a pulsed operation,” Ticoş explains. “For a fraction of a second (100 µs) the current is very high (several kiloamps) and the force pushing the plasma is quite strong.” During a pulse, the plasma is expelled at a very high speed – several kilometres per second – and so can simply blow dust away from an area two to four times bigger than the diameter of the jet.

An advantage of the plasma broom is that it uses low-pressure CO2 as the gas between the electrodes. This is particularly ideal for operation on Mars as the atmospheric pressure there is 150 times lower than on Earth and the atmosphere is 96% CO2. This means the gun will be able to function in “open” Martian atmosphere without the need for a pump or gas bottle. Ticoş and colleagues have also considered the energy required for the cleaner to function on Mars. This depends on the voltage the gun operates at and can vary between a few hundred to a few thousand Joules per pulse. “We did an energy budget estimate taking into account the solar irradiance on Mars,” says Ticoş, “and it appears perfectly feasible to fire a few shots even on a daily basis for cleaning the solar panels, which will boost considerably the energy production rate.”

Essentially, they are using ion engine concepts to create a can of dust-off, using the Martian atmosphere itself as the can.

Hat tip Mike Buford.

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The Moon’s dirtiest secret: Does its dust levitate?

The Moon’s dirtiest secret: Does its dust levitate?

This is a serious mystery left over from the Apollo missions which has significant ramifications not only for future research (the dust would interfere badly with any astronomical observatories) but also for any colonies that are eventually established.

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Astronomers have proposed that the cloud of dust that surrounds about 50% of the supermassive black holes at the center of galaxies comes from destroyed planets

Science better than fiction: Astronomers have proposed that the cloud of dust surrounding about 50% of the supermassive black holes at the center of galaxies comes from planets that were ripped apart and smashed by that black hole.

Collisions between these rocky objects would occur at colossal speeds as large as 1000 km per second, continuously shattering and fragmenting the objects, until eventually they end up as microscopic dust. Dr. Nayakshin points out that this harsh environment – radiation and frequent collisions – would make the planets orbiting supermassive black holes sterile, even before they are destroyed. “Too bad for life on these planets”, he says, “but on the other hand the dust created in this way blocks much of the harmful radiation from reaching the rest of the host galaxy. This in turn may make it easier for life to prosper elsewhere in the rest of the central region of the galaxy.”

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The battle in Congress of the EPA’s effort to regulate dust

The battle in Congress over the EPA’s effort to regulate dust.

Not surprisingly, the Democrats all support the EPA’s effort, while there are Republicans who oppose. What I consider significant is that more than a hundred agricultural organizations oppose the regulations.

One of the agricultural groups that is supporting the bill [to block the EPA regulations], the National Association of Wheat Growers (NAWG), wrote a letter to the committee last month, saying that a slight raise in overall particulate matter standards would require the EPA to regulate farm dirt under the current standards. “And, for what purpose? Scientific studies have never shown rural dust to be a health concern at ambient levels,” said the NAWG letter. [emphasis mine]

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