| science
and technology |
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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related
material
“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.
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
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.
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 |
