HYDERABAD, SEPT 14: Indian Space Research Organisation (ISRO) is proposing to build recoverable, reusable satellites for conducting microgravity experiments in space. The move, if it succeeds, will put India in the company of the US, Russia, Germany and China, which currently operate satellites exclusively for microgravity studies."It is still in the proposal stage and not an approved programme yet," an ISRO official told PTI on telephone. He said ISRO will be able to build the satellite in three years from the word `go' if the Indian scientific community came out with proposals for experiments that justified the construction of the satellite that would cost Rs 200 crore.Unlike objects on the ground which are subject to the pull of gravity, those inside an orbiting satellite float in almost zero gravity. Scientists hope that entirely new kind of materials can be produced in the high vaccum, gravity-free conditions existing inside satellites.A design of the Microgravity, Applicatiors Recoverable Satellite (MARS) is already on ISRO's drawing board. Weighing 900-kg, it will operate at 500-km circular orbit for up to three months before being deorbited and brought down to earth by parachute.It can be reused up to ten missions and launched by ISRO's Polar Satellite Launch Vehicle (PSLV), according to officials at the ISRO Satellite centre in Bangalore which will build it.A report authored by these officials and published in the journal Current Science says that MARS can provide half a cubic meter of space for microgravity experiment payloads weighing up to 250 kg. It has been estimated that sending one kg payload on MARS would cost Rs. 3 lakh if launched by PSLV."The important feature of this satellite is that it canbe reused for up to 10 missions bringing down the costs further," the authors said. The satellite is, however, anticipated to come in only in the second phase of the "national level programme on microlgravity research" for which ISRO invited research proposals from Indian scientific community.In the first phase of the programme, microgravity experiments will be conducted in special modules dropped from high altitude balloons - a technique known as atmospheric balloon-drop tests.The ISRO officials said while developing a reusable satellite platform is the "long-term" goal, "the balloon-drop" option is taken up to provide "hands-on experience" in designing and conducting microgravity experiments "as it is the most economical and provides quicker access" to this technology.India has good experience in launching balloons for space science experiments. The National Balloon Facility in Hyderabad, a unit of the Mumbai-based Tata Institute of Fundamental Research, has been sending balloons for over three decades.The National Balloon Facility unit can launch balloons carrying one-ton payloands to an altitude of 40 kilometers. Free fall of the balloon payload from this height is expected to provide microgravity conditions for a period of about 60 seconds-long enough for certain microgravity experiments."A payload module capable of carrying multiple experiments in the area of materials science, fluids physics and biotechnology in a single mission is being designed for suitable aerodynamic configuration taking its reusability in account to minimise the mission cost," ISRO scientists said in their report.Ballon drop experiment will cost about Rs 3000 per kilogram of payload.Currently balloon drop facilities for microgravity studies are avaiable in Germany, Japan and China.Indian scientists are not new to microgeravity research and had their first (and last) opportunity to gain experience to gain in design and development of microgravity experiment during the joint Indo-Soviet manned flight of Salyut-7 space station in 1984.During this mission the Indian cosmonaut on board performed the experiment (on silver-germanium alloy) designed by scientists of India's National Metallurgical Laboratory.S C Chakravarty, head of ISRO's space science division, wrote in Current Science that ISRO has now decided to revive the interest in the field of microgravity research "in view of its recent achievements in satellite and launch vehicle technologies" and success in operating many satellite experiments for scientific investigations.The areas for which research proposals have been invited are material processing in space, fluid dynamics, space biology and biotechnology but ISRO says it will consider other areas if warranted.In another report in Current Science, K Chattopadhyay, a metallurgist at the Indian Institute of Science in Bangalore says growing large crystals, studies on liquid phase sintering, designing new material such as the polyurethane foam, and aerogel - the weightless solid - are some the experiments that could be taken up.As space stations are not easily accessible to developing countries because of the high cost, recoverable satellite is an attractive proposition for carrying out microgravity experiments, say ISRO scientists.They point out China has developed satellite recovery technology code-named FSW series and has successfully used it for conducting microgravity experiments.
