IISc testing new tech to dissipate heat of spacecraft

One of the biggest challenges faced during the Mars expeditions by various space agencies is the heat generated by a spacecraft while entering the atmosphere of the planet. Now, scientists at the Indian Institute of Science (IISc), Bengaluru, are experimenting with a new technology that can help in faster dissipation of heat on entry.

The technology has the possibility of drastically reducing the cost of space travel and making spacecraft reusable.  When a spacecraft starts to descend on the surface of a planet, a large amount of heat is generated due to the speed of descent. This heat could damage the spacecraft and requires an additional Thermal Protection System (TPS) that acts as a barrier between the high-temperature gas and the spacecraft.  At present, all spacecraft entering the Martian atmosphere are thermally protected by “ablation” cooling where the TPS material heats up and burns to form a hot gas that gets blown away.

“Ablation cooling is very expensive when reusability of the spacecraft is concerned,” said Prof K P J Reddy from the Department of Aerospace Engineering at IISc.

As an alternative, the scientists carried out an experimental study to investigate the effectiveness of a new method called “transpiration” cooling that involves passing a coolant gas through a porous wall that absorbs the heat and gets blown away. The coolant gas forms a film on the outer surface of the spacecraft, absorbing heat. The heated coolant gas is then flushed downstream by the continuous supply of gas from the spacecraft.

These experiments were carried out in conditions similar to the Martian atmosphere and under different internal energy levels, pressure conditions and volume. “Transpiration cooling is relatively cheaper when reusability of the spacecraft is concerned. With the recent flight test of ISRO on the reusable vehicle, we feel that transpiration cooling technique will be incorporated within next 10 years,” said Prof Reddy.