Get Lost In The Jovian Triangle / Moon Bricks

The three brightest southern sky evening sky objects — Jupiter, Spica and Arcturus — for a long, skinny triangle that spans three fists. Credit: Bob King

I stepped outside late last night and saw a crisp triangle in the stars with corners formed by Jupiter, Spica and Arcturus. The geometry in math books may be confusing to some, but everyone can understand triangles of stars and planets in the night sky. This one is very close to a right triangle, so called because one of its angles is a right angle or 90°. You can see this geometrical trick any clear night now through late August, when Jupiter and Spica melt into the western sky at dusk.

You’ll have no difficulty finding Jupiter Sunday night when it’s only 2.5° (about two fingers held at arm’s length) to the right of the moon. Created with Stellarium
This view is to-scale and shows the moon and Jupiter around 9:30 p.m. CDT on Sunday, May 7. Binoculars will probably only show Callisto and Ganymede, since they’re relatively far from the planet. You’ll probably need a small telescope to see the other two. Created with Stellarium

This Sunday (May 7) the waxing gibbous moon will pay a visit to Jupiter. That evening, only 2.5° will separate them, a small enough distance that both will fit easily inside the field of view of most binoculars. I’ve included a diagram to help you use the occasion to see several of Jupiter’s many moons. Remember, the key to discerning these dots of light is to focus sharply on a bright star, then point them at the planet. Brace your arms against something solid like a wall or tree to keep the binoculars from bouncing up and down with your heartbeat!

A triangular brick 3D printed out of simulated moon dust using concentrated sunlight. As raw material, the test used commercially available simulated lunar soil based on terrestrial volcanic rocks, processed to mimic the composition and grain sizes of genuine moon dust. The resulting bricks have the equivalent strength of gypsum, and are set to undergo detailed mechanical testing. Credit: ESA-G. Porter

One day, astronauts will return to the moon to build a colony and remain there for months or even years the way scientists do in Antarctica. They’ll need to build housing to control the temperature and shield the first lunar dwellings against space radiation and the constant rain of micrometeoroids. What better way than build bricks from moon dust using a 3D printer? A recent experiment has shown that bricks can be 3D printed out of simulated moondust using concentrated sunlight, proving at least in principle that future lunar colonists could one day use the same approach to build settlements on the Moon.

Advenit Makaya, who oversees a new brick-building project for the European Space Agency (ESA) is optimistic:  “We took simulated lunar material and cooked it in a solar furnace,” he said.

Multi-dome lunar base being constructed, based on the 3D printing concept. Once assembled, the inflated domes are covered with a layer of 3D-printed lunar regolith by robots to help protect the occupants against space radiation and micrometeoroids. Credit: ESA, Foster + Partners

Makaya used a 3D printer table to bake successive 0.1 mm layers of simulated moon dust at 1,832° F (1000°C). “We can complete a 20 x 10 x 3 centimeter (7.8″ x 3.9″ x 1.2”) brick for building in around five hours.” For his heat source he employed the solar furnace at the DLR German Aerospace Center facility in Cologne, Germany — 147 curved mirrors focused sunlight into a high-temperature beam to melt the soil grains together.

Some bricks show some warping at the edges because their edges cool faster than the center, so they’re still working on getting it right by increasing the printing speed so that less heat accumulates inside the bricks. The system also has to be adapted to function in the vacuum present on the virtually airless moon. But hey, they’re working on it.

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