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Dextre: a helping hand in space March 11, 2008

Posted by eyegillian in Canada, design, explore, science, space, technology.
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Space station mobile servicing systemThis morning’s launch of the shuttle Endeavour also launched the career of a new astronaut: Dextre.

The Dextre manipulator (or Special Purpose Dexterous Manipulator), a sophisticated dual-armed robot, is part of Canada’s contribution to the International Space Station (ISS). Designed for servicing the Station, Dextre can remove and replace small components on the Station’s exterior that require precise handling.

Like a mechanic in space, Dextre can pivot at the waist, and its shoulders support two identical arms with seven offset joints that allow for great freedom of movement. It is equipped with lights, video equipment, a stowage platform, and four robotic tools.

At the end of each arm is an orbital replacement unit/tool changeout mechanism, or OTCM-parallel jaws that hold a payload or tool with a vice-like grip. For fine manipulation tasks, Dextre has a unique technology: precise sensing of the forces and torque in its grip with automatic compensation to ensure the payload glides smoothly into its mounting fixture. To grab objects, each OTCM has a retractable motorized socket wrench to turn bolts and mate or detach mechanisms, as well as a camera and lights for close-up viewing. A retractable umbilical connector can provide power, data, and video connection feed-through to payloads.

Dextre in cargo bay of space shuttle EndeavorThe cargo bay of Shuttle Endeavour with the Canadian robot Dextre and the pressurized component of Kibo, the Japanese Experiment Module.

Dextre can accomplish tasks that require high precision and a gentle touch such as removing and replacing Station components, opening and closing covers, and deploying or retracting mechanisms. Some of the many tasks Dextre will perform include installing and removing small payloads such as batteries, power switching units, and computers, as well as manipulating, installing, and removing scientific experiments.

A typical task for Dextre would be to replace a depleted battery (100 kg) and engage all the connectors. This involves bolting and unbolting, as well as millimetre-level positioning accuracy for aligning and inserting the new battery.

Like the Canadarm2 and the Mobile Base System, Dextre can be controlled from a workstation inside the space station or by controllers on the ground in mission control centres in Houston, Texas and at Canadian Space Agency headquarters in Longueuil, Quebec. Its five cameras, including two pan/tilt cameras below its rotating torso, provide operators with multiple views of the work area.

Dextre, Canadarm2 and the Mobile Base System form a robotic system called the Mobile Servicing System (MSS). The MSS is built for the Canadian Space Agency by the Canadian company MD Robotics.


(Information and illustrations: Canadian Space Agency)

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Cosmic rays and the nature of solidity February 28, 2008

Posted by eyegillian in energy, learn, nature, science, space.
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cosmic raysWhen I visited the Ontario Science Centre recently, I became fascinated by the Cloud Chamber. I sat mesmerized, watching as particles zipped around like invisible jets, leaving quickly vanishing vapour trails behind. It was tough to get a photo that shows those ephemeral paths!

Here’s how it works: Cosmic rays are part of the natural radiation we are exposed to here on earth. As these radioactive particles pass through the air they collide with air molecules, detaching an electron from atom after atom, and leave behind a trail of ions. The ions are air molecules that have either lost an electron (leaving them with a positive charge) or picked up the freed electrons (giving them a negative charge). The cloud chamber contains super-saturated alcohol vapour, which clings in tiny drops to these ions to mark the trail.

Cosmic rays come mostly from protons in outer space. They continually bombard the earth and stream through everything that we would consider to be “solid”, including our bodies. We can’t see cosmic rays directly, but we can see the result of the rays’ interaction with the atmosphere in the display of the aurora borealis and aurora australis, for example.

When a cosmic ray enters the earth’s atmosphere, it collides with a nitrogen or oxygen atom in the air, creating a chain reaction which breaks apart the atoms and results in a shower of particles. Most of these particles have very low energy and decay or are absorbed into the atmosphere. The only particles that reach the ground are either very energetic or relatively stable. One such particle is the muon, a high-energy heavier version of the electron. At sea level, the flow of high-energy muons is about six muons per square inch per minute.

Now I’m not trying to assert any scientific thesis here; I’m sure any physicist could write ad infinitum about all these radioactive particles and the differences between electrons, ions, muons, protons, pions, etc. As a curious non-scientist, however, what I find particularly fascinating is the fact that a) there are so many types of “radiation” that are passing through our bodies every day; and b) that we are so permeable.

As I read about this phenomenon, some of what I learned in long-ago science classes comes back to me, how all the so-called solid objects which make up our world are not actually solid at all, but made up of a bunch of bouncing atoms. This brings a new kind of “seeing” to my observations of nature. And being actually able to “see” these speeding particles is a bonus; it somehow makes them a lot more real than anything in a school textbook.

particle trails

Photos by Seeing Is

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Related Links:
Build your own Cloud Chamber
Cosmic Extremes — a pdf pamphlet on cosmic rays
Cosmic Rays: A possible source

From fossil fuels to far-out energy February 26, 2008

Posted by eyegillian in Canada, energy, environment, explore, life, nature, science, space, technology, world.
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Oil derrickOne of the biggest issues right now — arguably bigger than even global warming — is energy: specifically, spiralling energy consumption in the face of depleting supply. In Canada, total energy consumption grew by 20.3% between 1980 and 1997, and we consumed five times the world average in terms of energy use, using an annual equivalent of 6.19 tonnes of oil per capita. (Source)

The energy strain has resulted in black-outs around the world, including the 12 hours or more that much of the northeastern U.S. and Ontario were out of power in August 2003, and massive blackouts that surged across much of western Europe in November 2006.

Meanwhile, world energy demand has been predicted to rise 45% by 2030 by which time oil production will fall by half — which is either a good or bad thing, depending on whether you’re selling the energy — although some claim that the earth will never run out of oil as long as there is new technology to help get at the hard-to-reach supplies.

While world powers jockey for control of the oil-rich Middle East, there is increased pressure in North America for new oil and gas sources in wilderness areas, such as the environmentally sensitive Chukchi Sea, which lies above the Arctic Circle between Alaska and Russia. On Feb. 1, 2008, a coalition of native Alaskans and conservation goups filed a lawsuit to stop the drilling in the environmentally sensitive area, but there will surely be more oil rushes to get at the huge reserves said to be in the North. 

But all is not lost. Last week, NASA announced that Saturn’s orange moon Titan has hundreds of times more liquid hydrocarbons than all the known oil and natural gas reserves on Earth. NASA’s Cassini spacecraft has mapped about 20 percent of Titan’s surface with radar, discovering lakes and seas which are estimated to contain more hydrocarbon liquid than Earth’s oil and gas reserves, and dunes that contain a volume of organics several hundred times larger than Earth’s coal reserves.

Steven Hobbs (Brisbane, Queensland, Australia)Ah, yes… Titan. Now that potential mining bonanza should be a challenge to technology. Let’s see, only -179 degrees Celcius. An environment of liquid methane and ethane and a mix of complex organic molecules called tholins. Titan is only about 50% larger than the moon, and it took the Cassini probe seven years to get there. Well, but I’d bet the job would pay an astronomical salary. Anyone up for it?

On the other hand, maybe we should start to think about Plan B, just in case we don’t get to Titan before our fossil fuels run out, just in case the story about endless energy reserves turns out to be a pipe dream.

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Related Links:
NASA: Titan’s Surface Organics Surpass Oil Reserves on Earth”
Titan Oil Reserves
Blackouts around the world
Times: “Energy crisis cannot be solved by renewables”
Guardian: “Steep decline in oil production…”

the marvelous moon February 21, 2008

Posted by eyegillian in explore, science, space.
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Lunar eclipse with Saturn & Regulus by Seeing Is

Thy shadow, Earth, from Pole to Central Sea,
Now steals along upon the Moon’s meek shine
In even monochrome and curving line
Of imperturbable serenity.

Thomas Hardy At A Lunar Eclipse (1903)

I was out in the cold clear winter air last night watching the eclipse. What an awe-inspiring scene! It seemed to me that when the moon was red and dark in the earth’s umbra, that it seemed more full and round and real than ever it does as the bright plate we are used to seeing. I wasn’t alone as I watched the sky — as the moon came into its full eclipse, doors opened and people rushed towards the next-door park to get a good look and a few photos. Although it was -10 degrees celcius, I saw 40 or 50 people out watching the moon, including a teacher who had set up a small telescope for a group of students to see the action close-up… and I’m sure to look at Saturn as well, a bright light to the moon’s left.

Every human culture has stared at the sky and told stories about the moon and its effect on people’s lives. From “honeymoons” to “once in a blue moon”, from legends about werewolves to Asian Moon Festivals, the moon has a strong attraction that affects more than the earth’s oceans.

I believe that telescopes wouldn’t have been invented if it wasn’t for the moon. Galileo, who unveiled his telescope in 1609, was the first person to map the craters of the moon. It’s fun to imagine how Galileo — whose telescope only had a 30x magnification — would enjoy the view from the Hubble Telescope, or the new James Webb Space Telescope, due to be launched in 2013.

Now that humans have walked on the moon — and I remember watching that first landing on a black-and-white TV at school — and mapped its surface, attention has turned to other planets in our solar system and beyond. But I don’t think that a “been there, done that” attitude should apply to the moon. Oh, I’ve been following with great interest the exploits of Rover and Spirit exploring Mars, and the Cassini-Huygens Probe’s photos of Saturn and its rings and moons, of course, but the earth’s own moon still fascinates me. The Russians are planning a series of moon expedition in a couple of years, and I will be following the new moon journey with keen interest.

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Related Links:
What is a Lunar Eclipse?
How a lunar eclipse saved Columbus