Why is ISRO choosing Musk’s SpaceX Falcon 9 over its own LVM3?

ISRO's LVM3 is a three-stage medium-lift launch vehicle

SpaceX SpaceX Falcon 9

In a first during the second quarter of 2024, India plans to launch a communications satellite (GSAT 20) utilizing SpaceX's Falcon-9 rocket, marking its initial collaboration with a venture spearheaded by billionaire Elon Musk, who is also keen on growing his various enterprises within the country. The advanced satellite is designed to enhance broadband communication across India, particularly in its remote and underserved areas, according to a statement released by NewSpace India Ltd (NSIL), the commercial arm of ISRO.

But what could have propelled NSIL to choose SpaceX Falcon 9 over ISRO's own LVM3? The GSAT 20 weighs 4,700 kg, surpassing the maximum launch capacity of 4,000 kg through LVM3 currently held by ISRO, India's space agency. NSIL stated that they would completely own, manage, and finance the GSAT-20 satellite, a high-throughput system with a capacity of 48 gigabits per second. ISRO's LVM3 and SpaceX Falcon 9 are two launch vehicles that can carry satellites and other payloads into orbit. They have some similarities and differences in terms of their origin, cost, performance, and reusability.

For instance, ISRO's LVM3 is a three-stage medium-lift launch vehicle, whereas SpaceX Falcon 9 is a partially reusable medium-lift 2-stage vehicle. ISRO's LVM3 rocket is 43.5 meters long, weighs 640 tons when it takes off, and has a top section 5 meters wide for carrying the payload. On the other hand, the Falcon 9, designed to carry satellites and eventually crewed space missions, is a first orbital class, reusable two-stage rocket. It has a height of 69.9 meters and a launch weight of 549,054 kilograms (549.05 tons).

Space experts, such as Girish Linganna, say that ISRO's LVM3 costs about $54 million per launch, while SpaceX Falcon 9 costs about $62 million per launch for a new rocket and $50 million for a reused one. 'ISRO LVM3 can carry up to 10,000 kg to Low-Earth orbit (LEO) and 4,000 kg to Geostationary Transfer Orbit (GTO), while SpaceX Falcon 9 can carry up to 22,800 kg to LEO and 8,300 kg to GTO and has the capability to transport 4,020 kg to Mars. The interesting aspect is that ISRO's LVM3 has a success rate of 75 percent, while SpaceX Falcon 9 has a success rate of 96 percent. Also, ISRO's LVM3 is not reusable, while SpaceX Falcon 9 can land and reuse its first stage and fairings. Both launch vehicles have ambitious goals, such as launching crewed missions and exploring Mars,' Linganna told THE WEEK.

Space experts point out that as far as the payload capacity is concerned, ISRO's LVM3 impresses with its capacity to launch 4,000 kg to GTO and 8,000 kg to LEO. 'LVM3 specifically caters to heavier communication satellites, highlighting India's self-reliance in launching sizable payloads. In contrast, Falcon 9 has historically launched payloads exceeding 7,000 kg to GTO and holds the record for deploying 143 satellites on a single mission. While LVM3 showcases India's capability for self-reliant launches, SpaceX's Falcon 9's prowess extends beyond, being human-rated for NASA missions, certified for national security space launches, and adept at executing complex missions with a remarkable track record across multiple iterations,' remarked Srimathy Kesan, founder and CEO of Space Kidz India, which is into design, fabrication, and launch of small satellites, spacecraft, and ground systems.

She further explains that India's consideration of SpaceX for launching its heaviest satellites signifies a strategic move to leverage Falcon 9's robust track record in handling substantial payloads to GTO. 'Falcon 9's capability to transport the heaviest payloads, along with its successful track record, reliability, and versatility across mission types, becomes an attractive proposition for ISRO. Moreover, SpaceX's reusable design brings cost-effectiveness to satellite launches, a factor that India might weigh in as it seeks to optimize resources while expanding its satellite deployment capabilities. The notable success of Falcon 9 in deploying heavy payloads to GTO, coupled with its reusability, could potentially complement ISRO's efforts in efficiently launching heavier satellites,' added Kesan.

There are different thrusts for each engine. There are notably three stages of ISRO LVM3, which involves two Solid Boosters carrying 207 tonnes of propellant in 3 segments, generating average thrust of 3,578.2 kilonewtons and a peak thrust of 5,150 kilonewtons each. This initial thrust propels the rocket into the sky, marking the first stage of the launch. Then there is the L110 liquid stage, which is a liquid-fueled rocket stage equipped with two Vikas engines. Together, these engines produce a combined thrust of 1,532 kilonewtons. This stage is named for its fuel capacity, holding 110 metric tons of liquid fuel.

Post that, there is the C25 cryogenic upper stage that measures 4 meters in diameter and 13.5 meters in length, carrying 28 metric tons of LOX and LH2 propellant. The propellant is pressurized using helium stored in submerged bottles. This stage is powered by a singular CE-20 engine, capable of generating 200 kilonewtons of thrust.

Explaining the two stages of SpaceX Falcon 9, Linganna says that Merlin engines, made by SpaceX, are used in their Falcon 1, Falcon 9, and Falcon Heavy rockets, and these engines run on a type of kerosene called RP-1 and liquid oxygen (LOX). 'They were designed for recovery and reuse. The thrust produced is 845 kilonewtons. The first stage of the Falcon 9 rocket uses nine Merlin engines and tanks made of aluminum-lithium alloy, filled with liquid oxygen and a type of kerosene known as RP-1. The Falcon 9 can produce over 7,561.974 kilonewtons of thrust at sea level. The Falcon 9 rocket also features an interstage composed of composite material, connecting its first and second stages and equipped with pneumatic pushers for stage separation during flight. Additionally, at the base of the interstage, there are four grid fins which play a crucial role in controlling the rocket's descent back to Earth by manipulating the center of pressure. The Falcon 9's second stage uses one Merlin Vacuum Engine to carry its payload to the target orbit. This engine starts up shortly after the first stage separates and can be reignited several times to send different payloads to various orbits. The engine runs for 397 seconds and generates a thrust of 981 kilonewtons,' pointed out Linganna.

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