You Tell ‘em, Borg Lady

#work

#work

The second flight of Europe’s new Vega launcher is set for a 10:06 PM EST liftoff tonight. It carries 3 satellites for the European Space Agency, the Vietnamese government and students in Estonia.

The launch can be watched here.

  The Estonian satellite, although weighing a mere three pounds, will be testing a solar tether-like propulsion concept.

me too

Designing new aerodynamic vehicles typically requires a combination of multiple experimental and numerical techniques. The photo above shows a model for an unmanned flying wing-type vehicle. Here it’s tested in a water tunnel with dye introduced to the flow to highlight different areas. The model is at a high angle of attack (18 degrees) relative to the oncoming flow. This puts it in danger of flow separation and stall, the point where a wing experiences a drastic loss in lift. The smooth flow over the front of the model indicates it hasn’t reached this point yet, but notice how both the green and red dyes are separating from the model and becoming very turbulent over the back of the wing. If the model were pushed to an even higher angle of attack, that separation point would move further forward, bringing stall that much closer. (Image credit: L. Erm and J. Drobik; research credit: R. Cummings and A. Schütte)

Things Programmers Shout #654

Shout I overheard at work here at NASA. “It’s not like it’s rocket science!” “I will compile your code to a flash drive and send it to the damn sun if you don’t stop it with the null errors.” // submitted by  @space-husband

Asteroid impacts are a major force in shaping planetary bodies over the course of their geological history. As such, they receive a great deal of attention and study, often in the form of simulations like the one above. This simulation shows an impact in the Orientale basin of the moon, and if it looks somewhat fluid-like, there’s good reason for that. Impacts like these carry enormous energy, about 97% of which is dissipated as heat. That means temperatures in impact zones can reach 2000 degrees Celsius. The rest of the energy goes into deforming the impacted material. In simulations, those materials – be they rock or exotic ices – are usually modeled as Bingham fluids, a type of non-Newtonian fluid that only deforms after a certain amount of force is applied. An everyday example of such a fluid is toothpaste, which won’t extrude from its tube until you squeeze it.

The fluid dynamical similarities run more than skin-deep, though. For decades, researchers looked for ways to connect asteroid impacts with smaller scale ones, like solid impacts on granular materials or liquid-on-liquid impacts. Recently, though, a group found that liquid-on-granular impacts scale exactly the way that asteroid impacts do. Even the morphology of the craters mirror one another. The reason this works has to do with that energy dissipation mentioned above. As with asteroid impacts, most of the energy from a liquid drop impacting a granular material goes into something other than deforming the crater region. Instead of heat, the mechanism for dissipation here is the drop’s deformation. The results, however, are strikingly alike.  

For more on how asteroid impacts affect the moon and other bodies, check out Emily Lakdawalla’s write-up, which also includes lots of amazing sketches by James Tuttle Keane, who illustrates the talks he hears at conferences! (Image credits: J. Keane and B. Johnson; via the Planetary Society; additional research and video credit: R. Zhao et al., source; submitted by jpshoer)

For humans, swimming is relatively easy. Kick your legs, wheel your arms, and you’ll move forward. But for microswimmers, swimming can be more complicated. For them, the world is a viscous place, and the rules that we swim by can’t help them get around. In a highly viscous world, flows are reversible. Kick one limb down and you might move forward, but when you pull the limb up, you’ll be sucked right back to where you started. So microswimmers must use asymmetry in their swimming. In other words, their recovery stroke cannot be the mirror-image of their power stroke. A new study suggests that simple elastic spheres could make good microswimmers through cyclic inflation and deflation. When the sphere deflates, it buckles, making a shape unlike its inflating one. This difference in shape change is enough to propel the sphere a little with each cycle. Right now the test system is a macroscale one, but the researchers hope to continue miniaturizing. (Image and research credit: A. Djellouli et al.; via APS Physics; submitted by Kam-Yung Soh)

Reinventing the Wheel

Planning a trip to the Moon? Mars? You’re going to need good tires…

Exploration requires mobility. And whether you’re on Earth or as far away as the Moon or Mars, you need good tires to get your vehicle from one place to another. Our decades-long work developing tires for space exploration has led to new game-changing designs and materials. Yes, we’re reinventing the wheel—here’s why.

Wheels on the Moon

Early tire designs were focused on moving hardware and astronauts across the lunar surface. The last NASA vehicle to visit the Moon was the Lunar Roving Vehicle during our Apollo missions. The vehicle used four large flexible wire mesh wheels with stiff inner frames. We used these Apollo era tires as the inspiration for new designs using newer materials and technology to better function on a lunar surface.

Up springs a new idea

During the mid-2000s, we worked with industry partner Goodyear to develop the Spring Tire, an airless compliant tire that consists of several hundred coiled steel wires woven into a flexible mesh, giving the tires the ability to support high loads while also conforming to the terrain. The Spring Tire has been proven to generate very good traction and durability in soft sand and on rocks.

Spring Tires for Mars

A little over a year after the Mars Curiosity Rover landed on Mars, engineers began to notice significant wheel damage in 2013 due to the unexpectedly harsh terrain. That’s when engineers began developing new Spring Tire prototypes to determine if they would be a new and better solution for exploration rovers on Mars.

In order for Spring Tires to go the distance on Martian terrain, new materials were required. Enter nickel titanium, a shape memory alloy with amazing capabilities that allow the tire to deform down to the axle and return to its original shape.

These tires can take a lickin’

After building the shape memory alloy tire, Glenn engineers sent it to the Jet Propulsion Laboratory’s Mars Life Test Facility. It performed impressively on the punishing track.

Why reinvent the wheel? It’s worth it.

New, high performing tires would allow lunar and Mars rovers to explore greater regions of the surface than currently possible. They conform to the terrain and do not sink as much as rigid wheels, allowing them to carry heavier payloads for the same given mass and volume. Also, because they absorb energy from impacts at moderate to high speeds, there is potential for use on crewed exploration vehicles which are expected to move at speeds significantly higher than the current Mars rovers.

Airless tires on Earth

Maybe. Recently, engineers and materials scientists have been testing a spinoff tire version that would work on cars and trucks on Earth. Stay tuned as we continue to push the boundaries on traditional concepts for exploring our world and beyond.  

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.  

I don’t doubt it