 |
|
| SCIENCE & TECHNOLOGY |
|
|
|
Sky ramp technology to launch satellites Liquid water on Mars?
|
|
|
|
|
Sky ramp technology to launch satellites
For the past 40 years of space technology, the multistage rockets have been the only method for launching satellites. This method has proved to be very There is always a dire need of spacecraft launching techniques, which are less expensive. The Scientists at LaunchPoint Technologies in Goleta, California have suggested the Sky Ramp Technology (SRT) in which a huge launch ring would fling a satellite into orbit. The huge launch ring would be a 2 km wide ring of super conducting magnets, which would be able to fire a satellite off a ramp at a speed of 8 km/hr, fast enough to put it into the orbit. The launch ring will be similar in some ways to a big particle accelerator. The particle accelerator used in experimental physics provides tremendous kinetic energy to the charged particles before they hit the target. The launch ring differs from the particle accelerator in the sense that it would have a circular track and the super conducting magnets placed around the track will provide the much-needed speed to the Although the magnets had earlier been used to accelerate the satellites on straight tracks but that proved futile, as they required huge spike of energy for launching. The circular tracks have an advantage over the straight tracks that they can accelerate the satellites gradually over a period of several hours. The studies conducted at Launch Point Technologies, which are funded by US Air Force (USAF), concludes that the setup is technologically feasible and cost effective. The USAF has given the go-ahead for more in-depth study and to build a small test version of launch ring measuring 20 to 50 meters across. The satellite to be launched will be encased in an aerodynamic cone-shaped shell to protect it from the intense heat generated during the launch. The cone-shaped shell would be attached to a sled designed to respond to the forces from the super-conducting magnets. When the sled is being accelerated to its top speed of 10 km/sec., the cone would be separated from the sled by means of laser and pyrotechnic devices. After separation from the sled, the cone would skid into a side tunnel where it will lose some of its speed due to friction against the walls of the tunnel. The tunnel would further direct the cone to a ramp angled at 30 degree to the Finally, the cone would be launched towards space at a speed of Mach.23 i.e. 8 km/sec. A rocket at the back end of the cone would also be used to adjust its trajectory to place in a proper orbit. During the launch, the cone would attain an acceleration of more than 2000 times the acceleration due to gravity (i.e. 2000g) and such a huge acceleration may be an obstacle for communication satellites. But James Fiske of LaunchPoint Technologies points out that electronic gadgets in laser guided artillery with U.S. military, survive even when fired out of the gun at up to 20000g. The space shuttle technology used so far utilises vertical launching position. Here, two solid rocket boosters, called the first stage and three space shuttle main engines, called the second stage, provide the thrust. During the first two minutes of flight, the solid fuel in two boosters gets exhausted and the booster casings are jettisoned from the shuttle. Thereafter, the shuttle propels on its main engines. The shuttle burns half of its fuel just to attain a speed of Mach 1.3, as it has to struggle to push through the dense lower atmosphere with full fuel load. But the NASA’s assisted SRT can reduce the fuel consumption by 25% to attain a speed of Mach 0.8. The calculations shows that with 300 launches per year, the SRT would be 12 times cheaper than the existing technology. In addition to launching of micro-satellites, the huge launching ring would also be an ideal way for delivering supplies such as food and water to support the human space flights. According to Fiske, as these materials are not sensitive to high accelerations, therefore, nearly all the materials could be shipped via launch rings. According to a researcher Alan Epstein at MIT, Cambridge, US, and the ring could potentially be used as a launching pad for long-range weapons. The use of SRT, thus, would result in major cost reduction of manned space activities. |
|
Liquid water on Mars? Striking images taken by NASA’s Mars Global Surveyor spacecraft suggest the presence of liquid water on the Martian surface, a tantalizing find for scientists wondering if the Red Planet might harbour life. The orbiting US spacecraft enabled scientists to detect changes in the walls of two craters in the southern hemisphere of Mars apparently caused by the downhill flow of water in the past few years, a team of scientists announced on Wednesday. Scientists long have wondered whether life ever existed on Mars. Liquid water is an important part of the equation. On Earth, all forms of life require water to survive. Scientists previously established the existence of war on Mars in the form of ice at the poles and water vapour, and pointed to geological features that appear to have been carved by water ages ago. Kenneth Edgett of Malin Space Science Systems in San Diego, a scientist involved in the research, said there had been a quest for “smoking gun” evidence for liquid water currently on Mars. “Basically, this is the ‘squirting gun’ for water on Mars,” Edgett told reporters. The scientists, whose research appears in the journal Science, compared images of the Martian surface taken seven years apart and also found 20 newly formed craters left by impacts from space debris. They said water seemed to have flowed down two gullies in the past few years, even though liquid water cannot remain long on the planet’s frigid, nearly airless surface because it would rapidly freeze or evaporate. That seemed to support the notion that underground liquid water may reside close enough to the surface in some places that it can seep out periodically. The images did not directly show water. But they showed bright deposits running several hundred yards (metres) seemingly left by material carried downhill inside the crater by running water, occasionally snaking around obstacles and leaving finger-shaped marks diverting from the main flow.
— Reuters |
|
THIS UNIVERSE
Is it true that if the earth extended all the way to the sun, then the noise the sun makes would deafen us all? What other effects would I am intrigued by your imagination. It is possible that you have been excited by a sentence in a comic book or a science fiction story! I do not know how you would like to extend the earth to touch the sun. One of the problems you would have is that your earth would be in immediate danger of vaporisation because of intense heat; indeed it would disappear, partly into the sun and partly by being blown away as a mass But in this fictional scenario we would overlook all this and address your curiosity — your wonder as to how noisy would be the sun. Your eardrums would not be able to stand the volume but that should be the least of your worries because you would not be left with any ears if you get near the sun. Perhaps your real question is: how loud would be the sound we would get here on earth if we could build a material bridge of some sort to the sun, even if it was only gaseous. I have a problem being very definitive about this. It is true that the surface of the sun is a violent place, with turbulent masses of gas and plasma and whirling magnetic fields. There would be explosions producing large solar flares. So one does expect a massive amount of sound produced. But would that propagate very far, even to the edge of the material bridge you might have built? You might have often seen high-flying aircraft at an altitude of 10 to 15 kilometers go rather quietly over your head. You do not get to hear the roar of their engines because the air in which they fly is very thin. Large number of meteors burning in the upper atmosphere seem to do their burning quietly because the sound they make does not propagate down to us. Upper layers of the sun are very hot (about 6,000 degrees Celsius) but the solar atmosphere at its outer edge is very rare and not a very good transmitter of sound. It is therefore likely that you would not hear very much before you are incinerated at a temperature of a million degrees in the chromo sphere. While we are busy with this childish science fiction we might as well consider some other consequences of the earth extending all the way to the sun. The distance to the sun is 150 million kilometers. An earth with this radius would be many orders of magnitude heavier than the sun. It would easily absorb the sun because of its gravitational field and will proceed on its way to becoming a composite star and later a massive black hole. Perhaps even juvenile science fiction should not be so daring. Making a bridge is also problematic. If you start from the earth end you would have a difficulty going much higher than Mount Everest because the bridge would start sinking into the earth since its pressure would begin to melt the rocks underneath - your bridge would just sink into the earth’s crust. This is one of the steps for which we would have to appeal to some kind of magic. Supposing we do become such magicians we would still need to know the direction in which to build because the earth keeps rotating! We could decide then to settle for a brief encounter with the sun when the final stage of our tower points towards the sun. For getting to the sun even a narrow bridge would use up a substantial part of the earth mass. Should our bridge be located close to the equator we might end up substantially increasing the moment of inertia of the earth. Conservation of angular momentum of the earth rotation would demand that the rate of this rotation slow down precipitately, almost coming to a stop! This would result in a world that has a near permanent day on one side and near permanent night on the other. In fact the day and night would acquire a seasonal rhythm. You would have seen that our dreaming is getting more and more silly as we proceed. It is perhaps a good time to stop and give up our crazy enterprise. We will also have to give up our wish to hear the acoustical cacophony on the sun by going close to it. We would rather turn to other methods of seeing and divining the explosive play and activity in our sun. In fact such methods
|
