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Wednesday, October 21, 2009

World's mysterious islands

World's mysterious islands

Easter Island 
One of the world's most famous archaeological sites, Easter Island is a small, hilly, now treeless island of volcanic origin some 2200 miles off the coast of Chile. Easter Island's mysterious 'Moai', giant head statues carved out of volcanic rock, draws tourists to the world's most remote inhabited island. The people of Easter Island called themselves the Rapa Nui. Where did they come from and why did they disappear? Science has put to rest some of the more bizarre theories, but questions remain.




Cook Islands
The Cook Islands, situated between French Polynesia and Tonga, consist of 15 islands in the South Pacific. The locals can tell you stories about Maungapu Mountain; how the sun was captured; and the infamous Ina and the shark, which describes how Ina's quest for an ocean God determined why sharks and certain fish have specific characteristics. Be careful not to get lost in the long passageways, underground among the bones. 






Canary Islands
Lying in the Atlantic Ocean to the west of Morocco is a series of volcanic islands known as the Canary Islands. Once termed 'the Fortunate Islands' by the Romans, the Canary Islands were formed by massive volcanic forces about 30 million years ago, although the Islands' history is shrouded in mystery. Some historians claim that the legendary continent Atlantis was located here. However, through all the myths, the Canary Islands are still thought of as a Garden of Eden or Alyssum. 




Oak Island
Oak Island is a 140-acre island in Nova Scotia, Canada. The island is noted as the location of the so-called Money Pit, a site of numerous excavations to recover pirate treasure believed by many to be buried there. The pit has been explored to more than 150 feet. The treasure, if any, which was buried, is still there, protected by an ingenious booby trap that floods the pit with sea water anytime someone gets close.





Orkney Islands
The Orkney Islands, off Scotland's northern coast, are well-known for their rich oral history and legends; they were once considered the home of fairies, witches, and ghosts. Here you may learn of the white nun who haunts Saint Magnus Cathedral, appearing only to those who circle it three times at night; of sailors lost at sea, stolen by a lovelorn mermaid in search of a husband; and of the island's standing stones, sleeping giants in disguise that wake on New Year's Day for a drink of water

Tuesday, October 13, 2009

Cool Things to do This Weekend

Cool Things to do This Weekend




The weekend has arrived again, but do you want it to be the same as every weekend? Here are 10 things to do this weekend that you probably wouldn’t normally do. Pick just one thing off the list and add something different to your weekend.

1. Visit a Planetarium
Plantariumcrop
Chances are, if you are reading this, you probably have at least a passing interesting in science and space.Why not go to your local planetarium this weekend? As well as getting the best view of the night sky that you can see from earth (unless you live in the Arctic maybe), Planetaria often have specialised shows on the weekends.

2. Take a Barista Coffee Course
Coffee Barista
Are you sick of making bad coffee? If so, why not see if you can find a good barista course this weekendand learn how to make coffee like a pro? If you can’t find one, you may be able to convince the barista at your local coffee shop to show you how it’s done.

3. Take a Defensive Driving Course
Grayaction
If you haven’t already done a Defensive Driving Course, now is as good a time as any to do it. You learn evasive techniques, safety tips, and get to race around obstacle courses. Not only do you have fun, but you learn to keep yourself safe on the road.

4. Test Drive your Dream car
16-Bentley-Continental-Gt
Most of us have a dream car (mine is a Bentley) – why not call your local dealer and organise a test drive? If it is particularly expensive you may have to do a bit of faking on the telephone so you sound like you can afford one. What could be nicer than driving your favourite car through the city. Occasionally you are allowed to take a car for half a day – if so, why not combine this one with number 9 (the Posh Picnic) and make a day of it!

Just paying the bills...

5. Visit a Day Spa
Spa-Jakkarat1
Men and women alike need to take care of their skin and bodies, so why not find a nice treatment at a day spa? At the least you can get a massage with aromatherapy. What better way is there to relax after a long week at work? I recommend doing this as early as possible in the weekend. After you are done and are feeling great, why not try number 6 (Theatre or Opera) for the evening?

6. Go to the Theatre or Opera
Lulu Bastille
I wonder how many readers have been to the Opera or the Theatre? Probably the majority haven’t. If you pick well, the opera can be very interesting – it is not like the old days where fat ladies prance around in old fashioned clothes. The same is true of the theatre. I would recommend giving a modern opera a try. Some composers you might find interesting: Alban Berg, Dmitri Shostakovich, Bela Bartok, Alfred Schnittke, Benjamin Britten, and Philip Glass. The photo above is from Berg’s opera Lulu which includes a lesbian countess and Jack the Ripper.

7. Take a Coach Tour 
Coach1
If you are new to your town, there is no better way to get to know it than taking a bus tour. You will learn about many interesting parts of the city you probably don’t know about. If you are a long time citizen of your town, this is a great way to discover new things about the city that you didn’t know. If you live close to another city that you don’t often visit, why not take a bus there and do a tour of that city?

8. Book a Last Minute Hotel Room
060404-Savoy-Entrance
This one is good for couples or groups. There are lots of resources on the internet to find last minute cheap hotel rooms. Why not book a night in a hotel you normally can’t afford and have an evening in with movies and alcohol. The best thing is that you don’t need to clean up the next day! Just remember to pack your anti-hangover cures.

9. Posh Picnic
Castleward Picnic
Everyone loves a picnic from time to time, but why not have a good old fashioned posh picnic? Make (or buy) little sandwiches with salmon, cucumber, egg, or any other posh sandwich filling. Make (or buy) a posh cake. Take a nice rug to sit on and take your best cutlery and real glasses and plates. Don’t forget the champagne – I recommend Perrier Jouët Belle Époque.

10. Visit an Old Friend
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We all have friends that we haven’t seen in a long time. Why not give them a call and get togetherthis weekend? One of the nicest ways to spend an evening is at home (at your own or your friends’) with beer or wine and good conversation. If the weather is good in your part of the world, have a barbecue and make it a night to remember.


Thursday, October 1, 2009

How Satellites Work

How Satellites Work
How is a Satellite Launched into an Orbit?


All satellites today get into orbit by riding on a rocket or by riding in the cargo bay of the Space Shuttle. Several countries and businesses have rocket launch capabilities, and satellites as large as several tons make it safely into orbit on a regular basis.


For most satellite launches, the scheduled launch rocket is aimed straight up at first. This gets the rocket through the thickest part of the atmosphere most quickly and best minimizes fuel consumption.






After a rocket launches straight up, the rocket control mechanism uses the inertial guidance system to calculate necessary adjustments to the rocket's nozzles to

 tilt the rocket to the course described in the flight plan. In most cases, the flight plan calls for the rocket to head east because Earth rotates to the east, giving the launch vehicle a free boost. The strength of this boost depends on the rotational velocity of Earth at the launch location. The boost is greatest at the equator, where the distance around Earth is greatest and so rotation is fastest.


How big is the boost from an equatorial launch? To make a rough estimate, we can determine Earth's circumference by multiplying its diameter by pi (3.1416). The diameter of Earth is approximately 7,926 miles (12,753 km). Multiplying by pi yields a circumference of something like 24,900 miles (40,065 km). To travel around that circumference in 24 hours, a point on Earth's surface has to move at 1,038 mph (1,669 kph). A launch from Cape Canaveral, Florida, doesn't get as big a boost from Earth's rotational speed. The Kennedy Space Center's Launch Complex 39-A, one of its launch facilities, is located at 28 degrees 36 minutes 29.7014 seconds north latitude. The Earth's rotational speed there is about 894 mph (1,440 kph). The difference in Earth's surface speed between the equator and Kennedy Space Center, then, is about 144 mph (229 kph). (Note: The Earth is actually oblate -- fatter around the middle -- not a perfect sphere. For that reason, our estimate of Earth's circumference is a little small.)


Considering that rockets can go thousands of miles per hour, you may wonder why a difference of only 144 mph would even matter. The answer is that rockets, together with their fuel and their payloads, are very heavy. For example, the February 11, 2000 lift-off of the Space Shuttle Endeavor with the Shuttle Radar Topography Mission required launching a total weight of 4,520,415 pounds (2,050,447 kg). It takes a huge amount of energy to accelerate such a mass to 144 mph, and therefore a significant amount of fuel. Launching from the equator makes a real difference.


Once the rocket reaches extremely thin air, at about 120 miles (193 km) up, the rocket's navigational system fires small rockets, just enough to turn the launch vehicle into a horizontal position. The satellite is then released. At that point, rockets are fired again to ensure some separation between the launch vehicle and the satellite itself.




Orbital Velocity and Altitude

A rocket must accelerate to at least 25,039 mph (40,320 kph) to completely escape Earth's gravity and fly off into space (for more on escape velocity, visit and .
Earth's escape velocity is much greater than what's required to place an Earth satellite in orbit. With satellites, the object is not to escape Earth's gravity, but to balance it. Orbital velocity is the velocity needed to achieve balance between gravity's pull on the satellite and the inertia of the satellite's motion -- the satellite's tendency to keep going. This is approximately 17,000 mph (27,359 kph) at an altitude of 150 miles (242 km). Without gravity, the satellite's inertia would carry it off into space. Even with gravity, if the intended satellite goes too fast, it will eventually fly away. On the other hand, if the satellite goes too slowly, gravity will pull it back to Earth. At the correct orbital velocity, gravity exactly balances the satellite's inertia, pulling down toward Earth's center just enough to keep the path of the satellite curving like Earth's curved surface, rather than flying off in a straight line

The orbital velocity of the satellite depends on its altitude above Earth. The nearer Earth, the faster the required orbital velocity. At an altitude of 124 miles (200 kilometers), the required orbital velocity is just over 17,000 mph (about 27,400 kph). To maintain an orbit that is 22,223 miles (35,786 km) above Earth, the satellite must orbit at a speed of about 7,000 mph (11,300 kph). That orbital speed and distance permits the satellite to make one revolution in 24 hours. Since Earth also rotates once in 24 hours, a satellite at 22,223 miles altitude stays in a fixed position relative to a point on Earth's surface. Because the satellite stays right over the same spot all the time, this kind of orbit is called "geostationary."Geostationary orbits are ideal for weather satellites and communications satellites.


The moon has an altitude of about 240,000 miles (384,400 km), a velocity of about 2,300 mph (3,700 kph) and its orbit takes 27.322 days. (Note that the moon's orbital velocity is slower because it is farther from Earth than artificial satellites.)
In general, the higher the orbit, the longer the satellite can stay in orbit. At lower altitudes, a satellite runs into traces of Earth's atmosphere, which creates drag. The drag causes the orbit to decay until the satellite falls back into the atmosphere and burns up. At higher altitudes, where the vacuum of space is nearly complete, there is almost no drag and a satellite can stay in orbit for centuries (take the moon as an example).
Satellites usually start out in an orbit that is elliptical. The ground control station controls small onboard rocket motors to provide correction. The goal is to get the orbit as circular as possible. By firing a rocket when the orbit is at the apogee of its orbit (its most distant point from Earth), and applying thrust in the direction of the flight path, the perigee (lowest point from Earth) moves further out. The result is a more circular orbit.






What is a Satellite Launch Window?
A launch window is a particular period of time in which it will be easier to place the satellite in the orbit necessary to perform its intended function.


With the Space Shuttle, an extremely important factor in choosing the launch window is the need to bring down the astronauts safely if something goes wrong. The astronauts must be able to reach a safe landing area where rescue personnel can be standing by. For other types of flights, including interplanetary exploration, the launch window must permit the flight to take the most efficient course to its very distant destination. If weather is bad or a malfunction occurs during a launch window, the flight must be postponed until the next launch window appropriate for the flight. If a satellite were launched at the wrong time of the day in perfect weather, the satellite could end up in an orbit that would not pass over any of its intended users. Timing is everything!


What is Inside a Typical Satellite?

Satellites come in all shapes and sizes and play a variety of roles. For example:
  • Weather satellites help meteorologists predict the weather or see what's happening at the moment. Typical weather satellites include the TIROS, COSMOS and GOES satellites. The satellites generally contain cameras that can return photos of Earth's weather, either from fixed geostationary positions or from polar orbits.


  • Communications satellites allow telephone and data conversations to be relayed through the satellite. Typical communications satellites include Telstar and Intelsat. The most important feature of a communications satellite is the transponder -- a radio that receives a conversation at one frequency and then amplifies it and retransmits it back to Earth on another frequency. A satellite normally contains hundreds or thousands of transponders. Communications satellites are usually geosynchronous.


  • Broadcast satellites broadcast television signals from one point to another (similar to communications satellites).


  • Scientific satellites perform a variety of scientific missions. The Hubble Space Telescopeis the most famous scientific satellite, but there are many others looking at everything fromsun spots to gamma rays.


  • Navigational satellites help ships and planes navigate. The most famous are the GPS NAVSTAR satellites.


  • Rescue satellites respond to radio distress signals (read this page for details).



  • Earth observation satellites observe the planet for changes in everything from temperature to forestation to ice-sheet coverage. The most famous are the LANDSAT series.




  • Military satellites are up there, but much of the actual application information remains secret. Intelligence-gathering possibilities using high-tech electronic and sophisticated photographic-equipment reconnaissance are endless. Applications may include:

Despite the significant differences between all of these satellites, they have several things in common. For example:
  • All of them have a metal or composite frame and body, usually known as the bus. The bus holds everything together in space and provides enough strength to survive the launch.

  • All of them have a source of power and batteries for storage.
    Arrays of solar cells provide power to charge rechargeable batteries. Newer designs include the use of fuel cells. Power on most satellites is precious and very limited. Nuclear power has been used on space probes to other planets . Power systems are constantly monitored, and data on power and all other onboard systems is sent to Earth stations in the form of telemetry signals.


  • All of them have an onboard computer to control and monitor the different systems.
  • All of them have a radio system and antenna. At the very least, most satellites have a radio transmitter/receiver so that the ground-control crew can request status information from the satellite and monitor its health. Many satellites can be controlled in various ways from the ground to do anything from change the orbit to reprogram the computer system.

  • All of them have an attitude control system. The ACS keeps the satellite pointed in the right direction.
    The Hubble Space Telescope has a very elaborate control system so that the telescope can point at the same position in space for hours or days at a time (despite the fact that the telescope travels at 17,000 mph/27,359 kph!). The system contains gyroscopes, accelerometers, a reaction wheel stabilization system, thrusters and a set of sensors that watch guide stars to determine position.