Science

Why ISRO Needs SpaceX (For Now)

Karan Kamble

Jan 15, 2024, 01:10 PM | Updated Jan 17, 2024, 01:05 PM IST

Starship liftoff through successful hot-stage separation. (SpaceX/Twitter)
Starship liftoff through successful hot-stage separation. (SpaceX/Twitter)

An Indian communication satellite will lift off from United States (US) soil using a US launch vehicle later this year.

NewSpace India Limited (NSIL), the commercial arm of the Indian Space Research Organisation (ISRO), has tied up with Elon Musk’s SpaceX for the launch of the GSAT-N2, earlier called GSAT-20.

NSIL is executing this demand-driven mission as part of its mandate to build, launch, own, and operate satellites based on customer demand.

In its first such assignment after the space-sector reforms of 2020, NSIL launched the GSAT-24 for direct-to-home service provider Tata Play.

The communication satellite flew to orbit on Europe’s Ariane 5 rocket from Kourou, French Guiana, in June 2022. Tata Play commenced the use of the GSAT-24 over a year later, in August 2023.

The satellite launch this year will be NSIL’s second demand-driven satellite mission.

The GSAT-N2 is a “high-throughput Ka-band satellite” — a communication satellite with higher data processing and transfer capacity than the conventional satellite for the same orbital spectrum (thus, cost-effective) and associated with a particular frequency band of 27 GHz to 40 GHz.

Indian service providers (no names specified by NSIL) have secured the bulk of the capacity on board the GSAT-N2, which will meet the needs of broadband, in-flight and maritime connectivity, and cellular backhaul services, with a focus on plugging the connectivity gap in remote or unconnected areas.

Curiously, while the GSAT-24 was launched by the European Ariane 5 rocket, NSIL has picked US company SpaceX for the launch of GSAT-N2 on its Falcon 9 rocket.

But Why SpaceX?

The communication satellite GSAT-N2 weighs 4,700 kilograms (kg). ISRO doesn’t yet possess a launch vehicle with the capability to lift a mass of more than 4,000 kg into a geosynchronous transfer orbit (GTO) of about 180 km x 36,000 km.

ISRO’s most powerful rocket yet, the Launch Vehicle Mark 3 (LVM3), has a 4,000-kg mass limit for transportation of satellites to GTO.

That is also why the LVM3 wasn’t picked previously to launch the GSAT-24, which weighed 4,180 kg. On that occasion, NSIL went with the much more capable Ariane 5.

The massive integrated Chandrayaan-3 spacecraft, which the LVM3 launched into an elliptic parking orbit of roughly 170 km x 36,500 km, weighed 3,900 kg, which, again, fell within LVM3’s payload mass capability.

The LVM3 rocket has, however, launched heavier payloads exceeding 4,000 kg in the past. For instance, it launched 36 OneWeb India satellites in two batches, whose total mass was around 5,800 kg each time.

But the catch there was the type of orbit into which the 72 satellites were launched — for deployment into low-Earth orbit (LEO), India’s heavy-lift launch vehicle can accommodate payloads of up to 8,000 kg.

While it isn’t able to deploy the GSAT-N2, and previously the GSAT-24, the LVM3 has successfully carried GSAT missions to orbit over the years.

The rocket’s first two developmental flights saw the launch of GSAT-19 and GSAT-29 communication satellites with a lift-off mass of 3,136 kg and 3,423 kg in June 2017 and November 2018, respectively. Both those satellites were within the 4,000-kg mass capability.

Foreign Rockets For Heavy Lifting

For the upcoming GSAT-N2 mission, SpaceX’s Falcon 9 rocket will perform the launch duties.

The Falcon 9 is the world’s first orbital-class reusable rocket. It is a two-stage rocket with the capability to launch payloads weighing 8,300 kg to GTO and 22,800 kg to LEO, respectively.

The GSAT-N2, weighing only 4,700 kg, is a comfortable fit for the Falcon 9.

SpaceX is capable of much more. Easily one of the world’s most powerful rockets, SpaceX’s Falcon Heavy can launch payloads of up to 26,700 kg to GTO and 63,800 kg to LEO.

Interestingly, SpaceX states payload mass specifications of 4,020 kg and 16,800 kg for Mars launches using the Falcon 9 and Heavy rockets, respectively. Interplanetary travel of payloads and people to the Red Planet has been integral to SpaceX’s space plans from the time of its founding.

Before SpaceX, India used the Ariane 5 rocket for the launch of many of its GSAT communication satellites. The Ariane 5 was capable of carrying payloads weighing over 10,000 kg to GTO and over 20,000 kg to LEO.

India didn't turn to the Ariane 5 once again because it retired last year.

The European launch vehicle served lift-off needs for 27 years before making its final flight in July 2023. Its much-delayed successor, Ariane 6, is under development and undergoing the necessary tests on the path to operationalisation.

Self-Reliance In Heavy Lifts?

India’s space agency is developing a launch vehicle to carry payloads exceeding a mass of well over 4,000 kg — the kind for which ISRO is having to rely on SpaceX this year.

It’s called the “Next (or New) Generation Launch Vehicle” or NGLV for now and is being developed as a three-stage, partially reusable rocket. The partial reusability (most likely of the first stage) will help cut down the cost of access to space — a key goal for an agency like ISRO that espouses frugal engineering.

The NGLV will be able to lift 8,900 kg and 16,900 kg of payload to GTO and LEO, respectively. Developed as a commercial launch vehicle for both governmental and private use, the rocket might fly for the first time in 2030.

The time frame is of particular interest because India plans to have its Bharatiya Antariksha Station ready and up in orbit by 2035. The first module of this space station is set to be ready as early as 2028.

Additionally, India plans to land astronauts on the Moon by 2040.

A space station mission, deep space probes, and especially human lunar landing will necessarily require a more powerful rocket with a heavier launch capability than is currently available with ISRO. Thus, the development of the NGLV becomes crucial.

Speaking at the Indian Institute of Technology (IIT), Bombay (Mumbai), in December 2023, ISRO Chairman S Somanath said the NGLV engine “is already designed by ISRO” and that the agency is “currently in the process of prototyping” and have initiated testing “in smaller levels.”

Somanath also revealed in July last year that a “big team” working on the NGLV had come out “with a report on how this rocket should look, what are the technology inputs, what are the approaches we should do, where we should do, manufacturing, everything…”

The ISRO chief has previously expressed confidence that NGLV “development can happen without much investment,” thanks to the luxury of “facilities necessary to develop it today, right now.” He has also stressed on industry collaboration in building this rocket.

He sees a future where ISRO will have a variety of rockets sharing the launch load across the public and private sectors. “I hope that the smaller satellite launch markets will be served by the private companies; and the medium scale will be served by the PSLV; the heavy lifts and the interplanetary missions will be served by the NGLV,” Somanath has said.

Work In Progress — Other Rockets

Some rockets are closer to fruition than the NGLV at present.

The launch vehicles currently under development are the human-rated launch vehicle, the small satellite launch vehicle (SSLV), and the reusable launch vehicle – technology demonstrator (RLV-TD).

The human-rated launch vehicle is an upgraded LVM3 rocket for the crucial purpose of transporting humans to space. Naturally, the human-rated LVM3 will be the Gaganyaan launcher. It will carry the orbital module, consisting of a crew and a service module, to the intended 400-km LEO. Since astronauts will be ferried, the rocket will include a crew escape system to whisk the crew away to safety in case of an emergency.

ISRO’s latest launch vehicle, the small satellite launch vehicle (SSLV), is a three-stage rocket capable of launching a satellite weighing up to 500 kg into a 500-km planar orbit. It doesn’t cost as much as the conventional rockets, nor is it infrastructurally demanding; plus, it offers a low turnaround time, launch on demand, and accommodation of multiple satellites — all apt features for the launch of small satellites into orbit.

The SSLV has had two developmental flights so far. In its maiden flight in August 2022, the small-lift rocket fell short of injecting the two satellites on board — an earth-observation satellite and a cubesat — to a roughly 350-km orbit. In a do-over in February 2023, the SSLV successfully deployed an earth-observation satellite along with two passenger satellites into a 450-km circular orbit.

As for the RLV-TD, it is part of ISRO’s efforts to develop and test various technologies that would add up to a fully reusable launch vehicle in the future. The winged RLV-TD vehicle will be scaled up to serve as the first stage of India’s two-stage, reusable orbital launch vehicle.

Essential technologies like autonomous navigation, guidance, and control, reusable thermal protection system, and re-entry mission management were validated on a successful flight test of the RLV-TD on 23 May 2016.

More recently, in April 2023, ISRO successfully conducted the RLV autonomous landing mission using a scaled-down version of the RLV-TD at the Aeronautical Test Range in Karnataka’s Chitradurga. It was another major step towards India having its own reusable launch vehicle.

Karan Kamble writes on science and technology. He occasionally wears the hat of a video anchor for Swarajya's online video programmes.


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