Obviously the design criteria for four wheeled vehicles are somewhat different on other planets. This has yielded some of the most bizarre and fascinating vehicles ever proposed, from the giant Mobility Test Article test driven by Wernher von Braun to today's rovers which have ditched the most expensive component of all, the driver. Here are a variety of some of both classic and unusual space rovers from prototype to flown.

Hyperion Power Generation, a startup building compact nuclear power reactor units that are “about the size of a typical backyard hot tub”, says commercial deployments could start as early as 2013. The release quotes the company’s CEO John “Grizz” Deal, who says the Santa Fe, New Mexico-based startup has advanced development of its device enough to be able to reach that goal. The company says it initially plans to make 4,000 units — each being able to generate 70 megawatts of heat energy, or 27 megawatts of electricity from a steam turbine. That’s the equivalent power for 20,000 homes. There’s also the possibility of linking devices that could produce more power.

Engineers who design wearable devices that harvest human energy for power face a daunting dilemma: how do you collect a significant amount of power without making the user expend a lot of extra effort? Gadgets like hand-crank generators and windup radios require manual work from a user, and existing shoe-mounted generators produce less than one watt of power. A team of engineers has developed a modified knee brace that captures energy that would otherwise have been lost while the wearer walks. The generator produces about five watts--enough to power 10 cell phones simultaneously.

DIRECT is an alternative approach to launching missions planned under NASA's new mandate: The Vision for Space Exploration (VSE). DIRECT would replace the separate Ares-I Crew Launch Vehicle (CLV) and Ares-V Cargo Launch Vehicle (CaLV) with one single "Jupiter" launcher, capable of performing both roles. This change to NASA's architecture completely removes the costs & risks associated with developing and operating a second launcher system, saving NASA $19 Billion in development costs, and a further $16 Billion in operational costs over the next 20 years. DIRECT's single launcher system would use existing Space Transportation System (AKA the Space Shuttle) facilities and hardware to lift over 45 tons (in basic configuration) up to more than 100 tons (with an Upper Stage).

This patch of desert may resemble the moon, but a team of NASA scientists who came here to test lunar robots, rovers and spacesuits found spring weather in Eastern Washington can be worse than outer space. During the two-week exercise, howling wind blasted sand into every nook and crevice of the machines — some of which were venturing outside the lab for the first time. Rain squalls forced scientists to shield state-of-the-art prototypes under blue tarps.

Using concentrated solar energy to reverse combustion, a research team from Sandia National Laboratories is building a prototype device intended to chemically "reenergize" carbon dioxide into carbon monoxide using concentrated solar power. The carbon monoxide could then be used to make hydrogen or serve as a building block to synthesize a liquid combustible fuel, such as methanol or even gasoline, diesel and jet fuel. The prototype device, called the Counter Rotating Ring Receiver Reactor Recuperator (CR5, for short), will break a carbon-oxygen bond in the carbon dioxide to form carbon monoxide and oxygen in two distinct steps. It is a major piece of an approach to converting carbon dioxide into fuel from sunlight.

Imagine being able to use electronic devices by simply plugging them in to your clothing CSIRO has just received funding of $4.4 million to help bring this possibility a step closer CSIRO’s Flexible Integrated Energy Device (FIED) was one of eight proposals selected as part of the latest round of Defence Capability and Technology Demonstrator (CTD) Program funding announced last night.

An amplified photon thruster that could potentially shorten the trip to Mars from six months to a week has reportedly attracted the attention of aerospace agencies and contractors. Young Bae, founder of the Bae Institute in Tustin, Calif., first demonstrated his photonic laser thruster (PLT), which he built with off-the-shelf components, in December, 2006. The demonstration produced a photon thrust of 35 µN and is scalable to achieve much greater thrust for future space missions, the institute said. Applications include highly precise satellite formation flying configurations for building large synthetic apertures in space for earth or space observation, precision contaminant-free spacecraft docking operations, and propelling spacecraft to unprecedented speeds -- faster than 100 km/sec. “This is the tip of the iceberg," Bae said in a statement from the institute. "PLT has immense potential for the aerospace industry. For example, PLT-powered spacecraft could transit the 100 million km to Mars in less than a week.”

Sometimes a particular piece of plastic is just what you need. You have lost the battery cover to your cellphone, perhaps. Or your daughter needs to have the golden princess doll she saw on television. Now. In a few years, it will be possible to make these items yourself. You will be able to download three-dimensional plans online, then push Print. Hours later, a solid object will be ready to remove from your printer. It’s not quite the transporter of “Star Trek,” but it is a step closer. Three-dimensional printers have been seen in industrial design shops for about a decade. They are used to test part designs for cars, airplanes and other products before they are sent to manufacturing. Once well over $100,000 each, such machines can now be had for $15,000. In the next two years, prices are expected to fall further, putting the printers in reach of small offices and even corner copy stores.

On January 16, 2007, a dazzling blue flame blasted across the sands of the Mojave desert. In many respects, it looked like an ordinary rocket engine test, but this was different. While most NASA rockets are powered by liquid oxygen and hydrogen or solid chemicals, "we were testing a methane engine," says project manager Terri Tramel of NASA's Marshall Space Flight Center (MSFC). The main engine, built and fired by the NASA contractor team Alliant Techsystems/XCOR Aerospace, is still in an early stage of development and isn't ready for space. But if the technology proves itself, methane engines like this one could eventually be key to deep space exploration. Methane (CH4), the principal component of natural gas, is abundant in the outer solar system. It can be harvested from Mars, Titan, Jupiter, and many other planets and moons. With fuel waiting at the destination, a rocket leaving Earth wouldn't have to carry so much propellant, reducing the cost of a mission.

It may sound far-fetched, but the day is coming when lasers will beam power to spacecraft, lunar/Martian rovers, and sherpalike robots that carry payloads up a thin tether into the upper atmosphere and beyond. Although researchers worldwide concur that power-beaming capabilities are decades away, a range of experimental efforts give promise that lasers may, in the not too distant future, provide cheap, safe, and reliable access to space.

Students and faculty from five North Dakota colleges are testing a prototype Mars spacesuit in the Badlands. Students from the University of North Dakota, North Dakota State, Dickinson State, the state College of Science in Wahpeton and Turtle Mountain Community College in Belcourt designed the experimental suit with a $100,000 NASA grant.

A material that could enable spacecraft to automatically "heal" punctures and leaks is being tested in simulated space conditions on Earth. The self-healing spacecraft skin is being developed by Ian Bond and Richard Trask from the University of Bristol, UK, as part of a European Space Agency (ESA) project. The researchers have taken inspiration from human skin, which heals a cut by exposing blood to air, which congeals to forms a protective scab. "The analogy is the vascular system of the human body," Bond told New Scientist. "The system needs to be completely autonomous."

As a potent greenhouse gas, methane has been getting a bad rap � especially with the recent news that methane generated by plants may be a significant factor in global warming. But as a potential rocket fuel, methane's stock has been going up � because of its efficiency, portability, storability and relatively low toxicity, and also because it could conceivably be manufactured on Mars. In its vision for space exploration, NASA has touted a liquid oxygen/methane combination as the best system for future spacecraft engines. The space agency refers to the methane concept liberally in its Exploration Systems Architecture Study, and has said it should be taken into account for the Crew Exploration Vehicle that will one day take the place of the space shuttle fleet.

An Extraordinary "hyperspace" engine that could make interstellar space travel a reality by flying into other dimensions is being investigated by the United States government. The hypothetical device, which has been outlined in principle but is based on a controversial theory about the fabric of the universe, could potentially allow a spacecraft to travel to Mars in three hours and journey to a star 11 light years away in just 80 days, according to a report in today's New Scientist magazine. The theoretical engine works by creating an intense magnetic field that, according to ideas first developed by the late scientist Burkhard Heim in the 1950s, would produce a gravitational field and result in thrust for a spacecraft.