The troughs appear to be stretch marks called extensional faults – troughs formed as a result of part of the surface expanding. The expansion may have occurred when volcanic activity injected material below the surface in the area, or when the surface rebounded after being pushed down by impacts.
A 40-kilometre crater sits near the centre of the radiating troughs. "What isn't clear is what is the relationship of that crater to the radial trough complex," Prockter says. "Did it help to form some or all of the troughs? Did it simply impact serendipitously at the bull's-eye?" source
SpaceX tests multiple rocket engines for first time
29 January 2008The commercial rocket company Space Exploration Technologies (SpaceX) is one step closer to creating a reusable heavy-lift launch vehicle after its Falcon 9 rocket passed a multi-engine test earlier this month.
The test was conducted on 18 January at the company's trial facility outside McGregor, Texas, US. Two Merlin 1C engines operated at full power during the test while attached to a rocket that was strapped to the launch pad.The achievement clears the way for more multiple-engine tests and a Falcon 9 test flight scheduled for later in 2008.
The final Falcon 9 design calls for nine Merlin engines generating over 450,000 kg (1 million pounds) of thrust, or four times the maximum thrust of a 747 aircraft.
But getting to that stage is not just a matter of stacking engines together. "There's a big difference when you have one engine and nine engines," says SpaceX spokesman Roger Gilbertson.
"The plumbing goes up substantially," he told New Scientist. "The fuel and the oxidiser tanks have to be able to drain essentially nine times faster. You need to flow all of those liquids down to those engines, delivering them as needed, so the plumbing there is very elaborate."
The team reported no significant problems during the transition to multiple engines after a successful single-engine test in November 2007. "It went very smoothly," Gilbertson says.
SpaceX plans to steadily increase the number of simultaneously firing engines on the rocket over the next few months. A three-engine test is scheduled for February, to be followed by a five, seven, and finally a nine-engine test.
The Falcon 9 will come in a medium and heavy model and is designed to carry payloads of up to 27,500 kg for low-Earth orbits, and up to 12,000 kg for geostationary orbits. The company is also designing a single-engine rocket, called the Falcon 1, to carry smaller payloads. Its next flight will take place in the next several months.
The same Merlin engine is used in both the Falcon 1 and the Falcon 9, and is intended to be recyclable. "
The company is also designing a crewed capsule, called the Dragon, that can carry up to seven people or a mixture of personnel and cargo. The SpaceX Dragon will be launched atop a Falcon 9 rocket and will be capable of docking with the International Space Station. SpaceX plans to have the capsule in service by 2009, in time for the retirement of NASA's shuttle fleet in 2010. source
My comment: Cool, what more I can say. I hope it works, because the Earth needs new rocket engines and new space technologies. Yes, the old Russian engines are still doing the work, but that doesn't mean we can rely on them forever. They are not created for real space exploration.
Shape-shifting robot forms from magnetic swarm
29 January 2008
The grand goal is to create swarms of microscopic robots capable of morphing into virtually any form by clinging together.
Seth Goldstein, who leads the research project at Carnegie Mellon University, Pittsburgh, in the US, admits this is still a distant prospect.
However, his team is using simulations to develop control strategies for futuristic shape-shifting, or "claytronic", robots, which they are testing on small groups of more primitive, pocket-sized machines.
These prototype robots use electromagnetic forces to manoeuvre themselves, communicate, and even share power.
One set of claytronic prototypes were cylindrical, wheeled robots with a ring of electromagnets around their edge, which they used to grab hold of one another. By switching these electromagnets on and off, the so-called "claytronic atoms" or "catoms" could securely attach and roll around each other (there's a video in the source page).
The robot's wheels were not powered, so they had to rely entirely on their magnets to manoeuvre themselves around. "These were the first mobile robots without any moving parts," says Goldstein. They also used their electromagnets to share power, to communicate, and for simple sensing.
Since using magnetic forces are less efficient at smaller scales, the team has now begun experimenting with electric forces instead.
The latest prototypes are box-shaped robots dubbed "cubes" that have six plastic arms with star-shaped appendages at the end of each.
These stars have several flat aluminium electrodes and dock together, face on, using static electricity. Electrodes on different stars are given opposing charges, which causes the stars to attract each other. Once connected, no power is needed to hold the stars together.
Tests have shown that it is possible to send messages and power to other cubes over the same links. "Our hope is to assemble around 100 cubes to experiment with ideas," Goldstein says.
Rob Reid at the US Air Force Research Lab is collaborating with the Carnegie Mellon team to develop even smaller prototype robots. Reid and colleagues can fold flat silicon shapes into 3D forms as little as a few hundred microns diameter."The physical mechanism for docking different pieces is really tough to do," says Alan Winfield, who works on artificially intelligent swarms at the Bristol Robotics Laboratory in the UK. "Most use mechanical latches with hooks." Although these physical connections are complex, they do not need power, Winfield points out, unlike magnetic connections.
Using electromagnetic forces may make more sense at smaller sizes, he adds. "My guess is that electrostatic connectors will come into their own on the micro scale where less power is needed to have a large effect," he says.
But software, not hardware, may be the biggest challenge facing researchers working on swarms of robots, he says: "Right now we just don't know how to design a system that produces complex overall behaviours from a group of simple agents."
My comment:I know I often post such articles, but there is a reason for doing it. First-we need to realise how complex this work really is, and second-every little step along the way-just like this- is leading to the Future. And every step is important. Of course, we all want to see the Maid-Robot tiding up our home. But it's not going to happen at once, and even when the commercial product is finally ready, all this steps will be important. So, I hope you enjoy.
Artificial letters added to life's alphabet
30 January 2008Two artificial DNA "letters" that are accurately and efficiently replicated by a natural enzyme have been created by US researchers. Adding the two artificial building blocks to the four that naturally comprise DNA could allow wildly different kinds of genetic engineering, they say.
Eventually, the researchers say, they may be able to add them into the genetic code of living organisms.
The diversity of life on earth evolved using genetic code made from arrangements of four genetic "bases", sometimes described as letters. They are divided into two pairs, which bond together from opposite strands of a DNA molecule to form the rungs of its characteristic double-helix shape.
The unnatural but functional new base pair is the fruit of nearly a decade of research by chemical biologist Floyd Romesberg, at the Scripps Research Institute, La Jolla, California, US.
Romesberg and colleagues painstakingly created a library of nearly 200 potential new genetic bases that are slight variations on the natural ones. Unfortunately, none of them were similar enough in structure and chemistry to the real thing to be copied accurately by the polymerase enzymes that replicate DNA inside cells.
The resulting large scale experiments generated many potential bases at random, which were then screened to see if they would be treated normally by a polymerase enzyme.
With the help of graduate student Aaron Leconte, the group synthesized and screened 3600 candidates. Two different screening approaches turned up the same pair of molecules, called dSICS and dMMO2.
The molecular pair that worked surprised Romesberg.
But the team still faced a challenge. The dSICS base paired with itself more readily than with its intended partner, so the group made minor chemical tweaks until the new compounds behaved properly.
"We now have an unnatural base pair that's efficiently replicated and doesn't need an unnatural polymerase," says Romesberg. "It's staring to behave like a real base pair."
In the near future, Romesberg expects the new base pairs will be used to synthesize DNA with novel and unnatural properties. These might include highly specific primers for DNA amplification; tags for materials, such as explosives, that could be detected without risk of contamination from natural DNA; and building novel DNA-based nanomaterials.
More generally, Romesberg notes that DNA and RNA are now being used for hundreds of purposes: for example, to build complex shapes, build complex nanostructures, silence disease genes, or even perform calculations. A new, unnatural, base pair could multiply and diversify these applications.
The most challenging goal, says Romesberg, will be to incorporate unnatural base pairs into the genetic code of organisms. "We want to import these into a cell, study RNA trafficking, and in the longest term, expand the genetic code and 'evolvability' of an organism."My comment: That's all very interesting. I really want to see what will happen to a living organism after plugging those new bases in. I mean, yeah, it sounds kind of cruel, but we're talking about one cell after all. And I'm so curious how it will respond to its new code. Whether it will recognise it as false, or it will just use it as the rest. And what will happen!