Flash Physics is our daily pick of the latest need-to-know developments from the global physics community selected by Physics World‘s team of editors and reporters
Building bricks made from “Martian soil”
The dream of building a human colony on Mars is a little closer to becoming a reality now that scientists in the US have shown that it should be possible to make super-strong bricks from Martian soil. Yu Qiao and colleagues at the University of California San Diego have developed a new process that compresses simulated Martian soil – dubbed “Mars-1a” – at high-pressure and ambient temperature. The result is a rock-like solid that is stronger than steel-reinforced concrete and ideal for construction. The simple fabrication procedure can be done with a piston press. It requires no energy-intensive thermal treatments, nor the addition to the soil of any additive binders that would need to be shipped to Mars from Earth. Instead, nanoparticles of iron oxide – a common component of Martian soil, and the source of its signature red colour – act as the bonding agent of the newly formed building material, connecting the larger basalt particles that make up the rest of the soil. Furthermore, not only can the material be fashioned into small bricks, but the fabrication process may also be compatible with additive manufacturing, which would allow larger structural components, and potentially even whole buildings, to be built up incrementally out of these Martian materials. The research is described in Scientific Reports and was supported by NASA, which has recently released its plans for the first manned mission to Mars in 2033.
Ground rips open and shuts during some earthquakes
In many earthquake disaster films, huge gashes rip open in the Earth, swallowing people and cars before snapping shut again. In the real world, however, earthquake experts have long believed that such dramatic events simply do not happen. Now Ares Rosakis, Hiroo Kanamori, Harsha Bhat and colleagues at Caltech in the US and École Normale Supérieure in France have shown that fast ruptures propagating up toward the Earth’s surface along a thrust fault can cause one side of a fault to twist away from the other, opening up a gap of up to a few metres that then snaps shut. Thrust faults occur in weak regions of the Earth’s crust during earthquakes, when one slab of rock slides up and over another. The team made its surprising discovery in the lab, using a transparent block of plastic with rock-like properties. The researchers cut the block in half and then put the two pieces back together under compression. A small explosive charge simulates the earthquake, causing the blocks to slide over each other. The optical properties of the plastic change depending on the stress it is under, allowing the team to watch stress waves move through the system. The experimental results can now be used to improve computer models of thrust faults. “The findings demonstrate the value of experimentation and observation,” says Rosakis, adding: “Computer models can only be as realistic as their built-in assumptions allow them to be.” The work is described in Nature.
US budget proposal leaves science mostly unscathed
The US Congress has reached a spending deal for the remainder of the financial year that largely leaves science unscathed. The deal between the leaders of the Senate and House of Representatives gives the Department of Energy’s Office of Science – the largest funder of the physical sciences – a 0.8% increase to $5.4bn, while NASA will get a 1.9% boost to $19.7bn. The National Science Foundation‘s budget, meanwhile, will be largely flat at $7.5bn. For the past seven months, the government has been operating under a “continuing resolution” that freezes spending at 2016 levels while a budget for 2017 is agreed. The House of Representatives will now vote on the bill followed by the Senate. Once through Congress, it will then land on Trump’s desk for a signature later this week. While scientists will breathe a sigh of relief that funding is secure until 30 September, in March Trump released his request for the 2018 budget that includes significant cuts to some agencies such as the Office of Science and the Environmental Protection Agency.