India’s space programme has scored a major win with the launch of ISRO’s GSLV-F17 carrying the EOS-05 satellite. Called the ‘Naughty Boy,’ this Friday lift-off packed a whole lot of firsts.
Most Earth observation satellites operate from low Earth orbit (LEO), typically hundreds of kilometres above the planet. “We will take it to the required orbit using the propulsion system of the satellite, and the assured lifetime of the satellite is seven years. That data can have applications ranging from agriculture and water-resource management to disaster response and weather-related monitoring. The ability to observe India repeatedly from a fixed orbital position also gives the country a capability that complements its existing constellation of Earth observation satellites in lower orbits.
EOS-05 is different. The GSLV-F17 is a 51.7-metre-tall, three-stage rocket with a lift-off mass of about 420.5 tonnes. Its third stage uses a cryogenic engine, and the vehicle has a said payload capability of around 2,250 kg for the relevant orbit class. The predicted injection altitude was around 29,934 km, while the mission achieved approximately 31,000 km. Narayanan said EOS-05 has an assured lifetime of seven years, while expressing confidence that it could function for more than nine years. EOS-05 has been described as a state-of-the-art Earth observation satellite capable of imaging across visible, infrared, multispectral and hyperspectral bands.
Because different wavelengths can reveal different characteristics of the Earth’s surface and atmosphere, that is significant.
Prime Minister Narendra Modi called the launch “yet another outstanding achievement by ISRO and a proud moment for our nation”. The PM said it reflected the “excellence, innovation and growing capabilities” of India’s space sector. ISRO Chairman V Narayanan described it as a “historical achievement”. Yet Narayanan said the vehicle exceeded its predicted performance during Friday’s mission. I am confident it will work for more than nine years,” he said. ISRO has said the mission will support disaster warning, cyclone monitoring and the monitoring of cloudbursts and thunderstorms. The satellite has been called the “eye in the sky” by a senior scientist involved in the mission. But Narayanan has made it clear that EOS-05 should not be viewed as a “spy satellite”. He said the Earth observation satellite would be capable of continuously scanning India, underlining its role in providing high-frequency Earth observation data. “Today, we have injected the heaviest satellite, a 2,367-kg satellite, using this launch vehicle,” he said. Once operationalised, Narayanan said, it will become India’s first dedicated imaging satellite from geosynchronous orbit, providing “strategic data” for the country. “This is a great achievement for our country’s space programme because this is the first Earth observation satellite that is going to be placed on the geo platform for national activities,” Narayanan said.
The mission’s significance also lies in what came before it. That mission failed after the cryogenic upper stage did not ignite as planned after liftoff from Sriharikota. An analysis of post-flight data indicated that an anomaly in the cryogenic upper stage led to the failure. It demonstrates the progress made by ISRO in improving the performance and reliability of the GSLV and its cryogenic propulsion system. Friday’s success thus provides a morale boost for the space agency as it enters a busy period of launches.
EOS-05 is a follow-up to the unsuccessful GSLV-F10/EOS-03 mission of August 12, 2021. Narayanan recalled that the first GSLV launch carried a payload of 1,536 kg. On January 12, the PSLV-C62 mission, carrying 16 satellites, failed to place them in their intended orbits after an anomaly in the vehicle’s third stage. Perhaps the biggest significance of EOS-05 lies in its potential use as a source of high-frequency Earth observation data for national applications. Earlier reporting noted: The GSLV-F17/EOS-05 mission is scheduled for launch at 2:55 am on September 4 from the Satish Dhawan Space Centre at Sriharikot. Earlier reporting noted: When most of India will be asleep in the early hours of September 4 at 2.55 am, the Indian Space Research Organisation (ISRO) will be at a crucial crossroads. From the Second Launch Pad at Sriharikota, the Geosynchronous Satellite Launch Vehicle (GSLV-F17) will thunder into the darkness carrying EOS-5, India’s first imaging satellite to operate from geosynchronous orbit, 36,000 kilometers above India.
The successful GSLV-F17 mission therefore represents more than the deployment of another satellite.
Since then, ISRO has gradually improved the vehicle’s performance by optimising its structural mass and improving its propulsion systems. The achievement is particularly important after another setback earlier this year. Earlier reporting noted: And yet this same rocket remains one of the crown jewels of India’s space programme.
What comes next?
EOS-05 is the heaviest ever launched by a GSLV and will become India’s first dedicated imaging satellite to operate from geosynchronous orbit once it reaches its operational orbit. The satellite was injected into a sub-geosynchronous transfer orbit after Friday’s launch and will use its own propulsion system to reach its required operational orbit at roughly 36,000 km above the Earth. That gives EOS-05 an important advantage: it can provide frequent observations of large areas rather than having to pass over a location only at intervals, as is the case with many lower-orbiting Earth observation satellites. At 2,367 kg, EOS-05 is the heaviest satellite ever launched by a GSLV vehicle, according to Narayanan. Friday’s launch was only the beginning of the EOS-05 mission. Narayanan said around 8,000 tests had been completed for Gaganyaan, which he described as a technology-intensive mission in which human safety remains the top priority. Against that backdrop, the successful GSLV-F17/EOS-05 launch is important not just for the satellite it carried, but also for the confidence it gives ISRO as it takes on increasingly complex missions.
Because the safety of astronauts is directly involved, unlike conventional satellite missions, the human-rated launch vehicle and associated systems require extensive testing. At that altitude, a satellite’s orbital period matches the Earth’s rotation. This allows it to remain over the same broad region and repeatedly observe it. The mission is designed to provide real-time or near real-time imaging of large-area regions at frequent intervals, helping with applications such as agriculture, disaster management and the monitoring of cyclones, cloudbursts and thunderstorms. That makes Friday’s mission an important demonstration of the launch vehicle’s growing capability. The satellite will now use its own propulsion system to raise its orbit to the required operational altitude. The satellite is expected to provide imagery that can be used for agriculture, forestry and monitoring water bodies, apart from disaster management. Its ability to repeatedly observe large areas from geosynchronous orbit could be particularly useful during rapidly developing events. The satellite was placed in a sub-geosynchronous transfer orbit and will undergo orbit-raising manoeuvres using its own propulsion system before being positioned in its required operational orbit. The launch also comes as ISRO prepares for an ambitious year ahead. Among the major programmes on the horizon is Gaganyaan, India’s human spaceflight programme. ISRO plans three uncrewed missions before crewed missions, with the first uncrewed Gaganyaan mission being prepared for launch this year.
Narayanan said the agency is targeting six more launches during the current financial year.
