Tuesday, January 18, 2011

Elevator to Space Closer

As I posted a couple of years back, our work on nanotubes and graphene was making the space elevator a plausible proposition.  Here we are with some calculations that indicate that it could be possible.

Certainly, this is needed to produce and support a large space station properly constructed to produce artificial gravity and best positioned at GSO to allow easy launches into interplanetary voyages.

Right now the technology has been demonstrated and may be even improved.   How about continuous nested nanotubes?  A series of coils could be taken up into space and the cable produced from them there, or alternately, they could be grown there.  Once one cable touches down the balance then have a guide.  The first cable may just be easy enough to pull off.

We still need to think out operating speed.  It may well need two cables to achieve the necessary efficiency and it needs to default correctly in the event of power failure.

An Escalator To Space - Not Very Far Away

by Staff Writers

Chennai, India (PTI) Jan 10, 2011

According to A. Senthil Kumar, once the infrastructure comes into position, the cost of carrying anything from earth to the GSO will be reduced to less than $250 per kg from the current $40,000 per kg.

The day may not be far away when an elevator attendant asks your preferred destination - low earth orbit (LEO) or geostationary orbit (GSO). Research is fast progressing in advanced countries on designing a space elevator, according to an Indian space expert.

"Space scientists and engineers are looking at the possibility of designing an elevator to travel into space. It is also time that Indian research institutions looked at developing carbon nanotube composite fibre, nano epoxy and laser power beaming," A. Senthil Kumar, deputy head at the Vikram Sarabhai Space Centre (VSSC), told IANS in an interview.

VSSC is part of the Indian Space Research Organisation (ISRO). Kumar, who addressed the 98th Indian Science Congress that concluded Friday, said: "The space elevator consists of a cable from an anchor in the ground to a counter weight located beyond geostationary orbit (GSO) that is 35,786 km away. A climber will move up on a carbon nanotube tether between earth and space."

The space lift would be utilised as a transportation and utility system for moving people, satellites and other items from earth to space.

According to Kumar, once the infrastructure comes into position, the cost of carrying anything from earth to the GSO will be reduced to less than $250 per kg from the current $40,000 per kg.

"The elevator can travel at 200 km per hour and reach the GSO in eight days," Kumar said.

He said 94 percent weight of the conventional rockets consists of fuel and other expendable infrastructure.

"What space agencies are looking at is safe access to the space at low cost," Kumar said.

He said a tall building on earth could be the anchor, from which a tether made of carbon nanotube composite fabric would extend to about 50,000 km towards the heaven.

"A climber/elevator powered by laser beaming of energy can travel over this tether. The payloads can be transported using these climbers to different orbits," Kumar said.

Speaking about the rope on which the climber would go up, the scientist said theoretically the carbon nanotube has a tensile strength of 300 gigapascal whereas the required strength for space travel is only 130 gigapascal.

The carbon nano fibres currently developed has tensile up to five gigapascal.

"The cable will be thickest at the top and taper down towards the earth. First a satellite will take the cable to the space wherefrom it will be unrolled towards the earth. The cable could be brought down without much movement and tied to the base station," Kumar explained.
And the challenges?

"Radiation, lightning, wind, meteors, space debris...but these are issues that can be dealt with," Kumar said.

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