In a span of 15 months, the Indian Space Research Organisation (ISRO) has completed all three autonomous landing tests of its spaceplane 'Pushpak' at the Aeronautical Test Range, Chitradurga, Karnataka. With the third and most complicated landing test accomplished at 7.10 am Sunday (June 23), ISRO will now have to work towards launching a larger version of this spaceplane to space on a modified rocket, testing the plane in earth orbit, and demonstrating its capability to re-enter the atmosphere, return to earth safely for a runway landing.
Known as a Re-usable Launch Vehicle Technology Demonstrator(RLV-TD) or 'Pushpak', the spaceplane is a sophisticated aerospace vehicle with civilian and strategic applications.
It must be noted that only the US and China are known to operate autonomous spaceplanes, and in the coming years, as ISRO makes further progress on 'Pushpak', India will be the third nation in this list. This is a vehicle that India eventually intends to develop and use to ferry small cargo (satellites and experiments) to space.
In the latest test, the 1.6-tonne spaceplane was underslung to an Indian Air Force Chinook heavy-lift helicopter, which carried the spaceplane to an altitude of 4.5 km and released it four-and-a-half kilometres away from the runway.
The plane was dropped in a position that was intentionally misaligned with the runway centreline at a sideways distance of 500 metres.
In the maiden landing test in April 2023, the plane was aligned straight to the runway, in the second test done in March 2024, the plane was 150 m misaligned with the runway centreline.
In all three tests, the spaceplane performed a flawless landing (at speeds of more than 320kmph), and performed a touchdown on the runway centreline.
In 2016, the RLV was carried to 65 km altitude by rocket, from there, the vehicle re-entered the denser parts of the atmosphere at Hypersonic speeds, almost five times the speed of sound and finally made a splashdown landing in the Bay of Bengal (simulated runway).
Dr Unnikrishnan Nair, the Director of ISRO's VSSC told WION that the latest landing trial is the most sophisticated one.
"At the time of drop, the space plane was intentionally at a sideways distance of 500 metres from the runway centreline. Yet again, the in-built systems performed their roles perfectly and ensured that the plane could make its third consecutive landing on the runway centreline. From an initial 500 metres distance from the runway centreline, the plane was finally at 11 cm or 0.1 metre from the runway centreline," he said, citing an image of the landed plane.
The final configuration of the RLV
In its present form, this RLV-TD vehicle is meant for demonstration purposes and the real vehicle would be about 1.6 times larger(comparable to an SUV). Once fully ready, the operational version of the RLV or 'Pushpak' is meant to be mounted atop a modified GSLV rocket and then launched into space, where the spaceplane would be autonomously carrying out on-board experiments and operating its payloads, or even placing small satellites in orbit.
The spaceplane could function in Low Earth orbit for up to a month and then autonomously perform de-orbiting, re-enter the Earth's atmosphere at very high speeds and temperatures and come in to land on the runway.
This ensures that the spaceplane can be fully re-used after carrying out a few refurbishments.
In many ways, the RLV is similar to the space shuttle operated by the US and the Soviet-era Buran spaceplane. However, the RLV is much smaller and not a crewed plane.
RLV is comparable to the American Boeing X-37B spaceplane and the Chinese 'Shenlong' (Divine dragon), which have been performing classified unmanned missions autonomously for many years.