As I posted a couple of years back, our work on nanotubes and graphene wasmaking the space elevator a plausible proposition. Here we are with some calculations thatindicate that it could be possible.
Certainly, this is needed to produce and support a large space stationproperly constructed to produce artificial gravity and best positioned at GSOto 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 intospace and the cable produced from them there, or alternately, they could begrown there. Once one cable touches downthe balance then have a guide. The firstcable 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 necessaryefficiency and it needs to default correctly in the event of power failure.
An Escalator To Space - Not Very FarAway
According to A. Senthil Kumar, once the infrastructure comes intoposition, the cost of carrying anything from earth to the GSO will be reducedto 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 preferreddestination - low earth orbit (LEO) or geostationary orbit (GSO). Research isfast progressing in advanced countries on designing a space elevator, accordingto an Indian space expert.
"Space scientists and engineers are looking atthe possibility of designing an elevator to travel into space. It is also timethat Indian research institutions looked at developing carbon nanotubecomposite fibre, nano epoxy and laser power beaming," A. Senthil Kumar,deputy head at the Vikram Sarabhai Space Centre (VSSC), told IANS in aninterview.
VSSC is part of theIndian Space Research Organisation (ISRO). Kumar, whoaddressed the 98th Indian Science Congress that concluded Friday, said:"The space elevator consists of a cable from an anchor in the ground to acounter weight located beyond geostationary orbit (GSO) that is 35,786 km away.A climber will move up on a carbon nanotube tether between earth andspace."
The space lift wouldbe 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 fromearth to the GSO will be reduced to less than $250 per kg from the current$40,000 per kg.
"The elevator cantravel at 200 km per hour and reach the GSO in eight days," Kumar said.
He said 94 percentweight of the conventional rockets consists of fuel and other expendableinfrastructure.
"What spaceagencies are looking at is safe access to the space at low cost," Kumarsaid.
He said a tallbuilding on earth could be the anchor, from which a tether made of carbonnanotube composite fabric would extend to about 50,000 km towards the heaven.
"Aclimber/elevator powered by laser beaming of energy can travel over thistether. The payloads can be transported using these climbers to differentorbits," Kumar said.
Speaking about therope on which the climber would go up, the scientist said theoretically thecarbon nanotube has a tensile strength of 300 gigapascal whereas the requiredstrength for space travel is only 130 gigapascal.
The carbon nano fibrescurrently developed has tensile up to five gigapascal.
"The cable willbe thickest at the top and taper down towards the earth. First a satellite willtake 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 basestation," Kumar explained.
And the challenges?
"Radiation,lightning, wind, meteors, space debris...but these are issues that can be dealtwith," Kumar said.