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running on water
studying locomotion.

“[...] the lack of answers to such questions is holding up the development of new technologies. It's one of the major reasons we can't build effective legged robots, [...] ”

“[...] Throughout their size range, they can run across water on their hind limbs at about 5 feet (1.5 meters) a second for a distance of approximately 15 feet (4.5 meters) before they sink to all fours and swim. The lizard is often called the Jesus Christ lizard in Central America [...]”

“ The stride is divided into three phases: the slap, the stroke, and the recovery. During the slap the foot moves primarily vertically downward. During the stroke it moves primarily backward. And during the recovery the foot moves up and out of the water, returning to the start position of the next step.”

“ According to analysis of their video, the lizards generate force for support during the slap phase, in which the lizards' foot plunges straight down, pushing water down and away from the foot while creating a pocket of air surrounding the foot.

“The support force generated by the slap is sufficient to keep the lizards' bodies above the water's surface during the stroke phase in which they propel themselves forward by kicking their leg back through the water.”

Article has more details, including a side bar on how insects (water-skaters) do it.

the web address for the article above is
https://www.abelard.org/news/science0411.php#jesuschrist_lizard



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“the first time an air-breathing scramjet-powered aircraft has flown freely”

update 2 scramjet test successful - new speed record

Preliminary data from the scramjet-powered research vehicle show its revolutionary engine worked successfully at approximately Mach 10, nearly 7000 mph, as it flew at an altitude of approximately 110,000 feet.

More details on the NASA site, including movies.

marker at abelard.org

NASA scramjet breaks sky speed record - update: flight delayed 'til tomorrow

Image credit: NASA Dryden Flight Research Center Photo Collection NASA photo: EDO4-0082-4
Image credit: NASA Dryden Flight Research Center Photo Collection
NASA photo: EDO4-0082-4

CTV News: John Vennavally-Rao on the X-43A
[web-tv report showing previous test flight]

NASA scientists have achieved a technological breakthrough with their successful test of an experimental high-speed jet, the X-43A.

In its 11-second flight, the aircraft reached speeds of 8,000 kilometres per hour.

What is a scramjet?
A conventional rocket carries its own oxygen supply,
A conventional jet engine draws in air and burns it with fuel so it expands in a combustion chamber.
A ramjet scoops oxygen directly from the atmosphere, while travelling at subsonic speeds.
A scramjet scoops oxygen directly from the atmosphere.
Scramjets operate at supersonic speeds.
A scramjet burns fuel in a stream of supersonic air compressed by the forward speed of the aircraft. In each case, the hot air is then forced out the exhaust nozzle to produce thrust.

related material
“the first time an air-breathing scramjet-powered aircraft has flown freely”

the web address for the article above is
https://www.abelard.org/news/science0411.php#scramjet_record

robot maintenance will prolong life of hubble telescope

Yet largely because of the Canadian robot named "Dextre," NASA has gone in less than a year from virtually writing off the Hubble to embracing a mission that will cost between $1 billion and $1.6 billion and approach in complexity the hardest jobs the agency has ever undertaken.

To do it, the United States must develop its first-ever robotic docking vehicle, fill a bag with tools that, in many cases, have not been invented, and use the robot repairman to unscrew j-hooks, open and shut doors and "drawers," disconnect and attach electric connectors, and rig jumper cables.

In the past, shuttle astronauts had the job of servicing Hubble, missions that required a few days of spacewalks lasting six hours each. Dextre "can work 24-7," Weiler said -- a fortunate feature, because robots are not as supple as humans. "Watching it is like watching grass grow," Weiler said.

the web address for the article above is
https://www.abelard.org/news/science0411.php#hubble_robot

update: ion-propelled craft now in moon orbit

The craft arrived at its destination thirteen months after launching from Earth. Although the moon is only 380,000km away in a straight line, SMART-1 orbited the Earth more than 300 times, and travelled 84m km. In fact, its journey comparable in length to an interplanetary cruise: at its closest, Venus is just 40m km away from us, and Mars is 35m km.

SMART-1 slotted into orbit at an altitude of 5000km, and will settle into its final orbit over the next few months. Its ion-propulsion engine will fire continuously for the next four days to help it stabilise. By January, it should be in an elliptical orbit, passing the moon at a distance of 300km over the South pole, and 3000km over the North pole.

marker at abelard.org

ion-propelled craft gently nears the moon

“Conventional spacecraft engines rely on chemical reactions to generate gas, which pushes the craft forwards as it squeezes out of the engine, in the same way as a deflating party balloon will fly across a room. But in space, mass is money. Whereas chemical engines must carry two fuel substances to react together (often hydrogen and oxygen), SMART-1's ion drive carries only xenon, making it lighter and cheaper.

“The success of SMART-1, which stands for Small Missions for Advanced Research in Technology, in reaching the Moon has proved that future spacecraft could use the same engines to get to Mercury and Mars, [...] ”

related material
ion engine under test in space

the web address for the article above is
https://www.abelard.org/news/science0411.php#ion_propulsion

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