Two technologies key to ISRO's ambitious Gaganyan mission

All the missions so far, including the Mars and the Moon missions, did not involve bringing back the spacecraft into earth's atmosphere.

Indian Space Research Organisation (ISRO) is tirelessly working towards the Gaganyan mission, India's first crewed spaceflight program, now that Prime Minister Narendra Modi has set a deadline for it. Modi on August 15 this year announced that an Indian astronaut would go into space by 2022.

ISRO may have undertaken a number of space programmes with great success rate, but sending a human being to space is a different ball game altogether. It is far more complicated than even Chandrayaan and Mangalyaan.

A manned space mission is very different from all other missions that ISRO has so far completed. For a manned mission, the key distinguishing capabilities that ISRO has to develop include the ability to bring the spacecraft back to Earth after the flight, and to build a spacecraft in which astronauts can live in Earth-like conditions in space.

All the missions so far, including the Mars and the Moon missions, did not involve bringing back the spacecraft into earth's atmosphere. Here, not does the module needs to be brought, it has to be brought back safely as there would be humans in it.

Other than these, ISRO also cannot rely on its workhorse PSLV. PSLV can carry payloads upto 2 tonnes, but a spacecraft carrying human beings is likely to weigh in excess of 5 to 6 tonnes. For this, ISRO has developed GSLV Mk-III which is a launch vehicle capable of carrying heavier payloads much further into the space.

There are a number of new technologies that ISRO has to develop to successfully carry out Gaganyan. In fact, ISRO has been testing these technologies quietly without making noise. Our focus here is to discuss two extremely important technologies that are important to any mission which involves sending humans into space.

Reentry and recovery technology:

All the ISRO missions so far involved sending satellites/orbiters out of the earth's atmosphere. But, when humans are being sent to space, then they have to be brought back, and that is a big technological challenge. When a spacecraft re-enters earth's atmosphere, it would have to withstand high temperatures, thousands of degrees, due to friction with the air.

Even when a meteorite enters the earth, the earth's gravity speeds up its descent and this causes friction with the air. This friction increases the temperature so much that most of the meteorites just vapourise before reaching the earth's surface. This is the reason we see shooting stars.

The spacecraft's re-entry into the atmosphere also has to be very precise both in terms of speed and angle, and even the slightest deviation could end in disaster. For this, a heat shield that can withstand thousands of degrees needs to be developed. After, re-entry, the spacecraft would land at a precise spot in the sea from where Navy or Coast Guard would bring it back to the mainland. So that is why speed and angle are important, the re-entry vehicle has to return in a pre-planned path in an accurate manner.

The good news is that ISRO has already tested this technology, but many more tests are needed.

Launch escape system or Crew Escape Mechanism:

If something goes wrong at any point during the launch, then there has to be way for the crew to escape so that lives can be saved. The mechanism ensures the crew module gets an advance warning of anything going wrong with the rocket, and pulls it away to a safe distance, after which it can be landed either on sea or on land with the help of attached parachutes. The system is typically controlled by a combination of automatic rocket failure detection, and a manual backup for the crew commander's use.

Even this has been tested by ISRO, but is not perfect yet.