The Indian Space Research Organisation (ISRO) has made their second launch of 2021 with a GSLV Mk. II rocket launching the EOS-03 satellite into geosynchronous transfer orbit. Liftoff from the Satish Dhawan Space Centre occurred at 05:43 local time (00:13 UTC on August 12).
Thursday’s launch proceeded to plan until shortly after third stage ignition, when telemetry in mission control indicated diverging attitude and altitude lines from pre-flight predictions. This is a developing story and this article will be updated when more information becomes available from ISRO.
EOS-03
Originally named Geo Imaging Satellite (GISAT) -1, the Earth Observation Satellite 03 (EOS-03) was to be India’s first geostationary Earth imaging satellite and the first of a pair of satellites that would provide complementary, dedicated coverage over India for:
- near real-time imaging of large areas of interest at frequent intervals,
- real-time monitoring of natural disasters, episodic events and any short term events, and
- obtaining spectral images for agriculture, forestry, water bodies as well as for disaster warning, cyclone monitoring, cloud burst / thunderstorm monitoring.
Based on ISRO’s I2K satellite bus, EOS-03 carried a 700 millimeter telescope with four imaging payloads: the Multispectral Visible Near-Infrared (MX-VNIR), the Multispectral Long-Wave Infrared (MX-LWIR), the Hyperspectral Visible Near-Infrared (HyS-VNIR), and the Hyperspectral Short-Wave Infrared (HyS-SWIR) instruments.
This mission is suffering a major failure during third stage flight. pic.twitter.com/OFD0kjBHey
— Chris Bergin – NSF (@NASASpaceflight) August 12, 2021
MX-VNIR would have given the highest resolution of up to 42 meters in six spectral bands. HyS-VNIR operates in 158 bands at resolutions up to 318 meters while HyS-SWIR covers 256 bands at resolutions up to 191 meters. MX-LWIR operates in six bands with a resolution up to 1,500 meters.
EOS-03 had a total mass of 2,286 kilograms at launch and was expected to operate for at least 10 years. Power was to be provided by a single solar array with three panels generating 2,280 watts. The satellite was expected to be positioned in geostationary orbit at 85.5 degrees East.
A second satellite, EOS-05 (or GISAT-2), is expected to launch in 2022 under current schedules.
The program’s re-designation from GISAT to EOS is part of an ISRO effort to return to more generic names for satellite families geared towards studying or returning images of the Earth. In doing so, the organisation is returning to a practice from the late-1980s through the 1990s when all of India’s Earth observation satellites were designated Indian Remote Sensing, or IRS.
This gave way to more specific names for individual satellites or programs beginning with the launch of Oceansat 1 (formerly IRS-P4) in 1999.
EOS-03 during encapsulation. (Credit: ISRO)
The EOS-01 satellite — launched in 2020 as part of the Radar Imaging Satellite (RISAT) program — was the first mission to bear this new designation. Upcoming Cartosat, Oceansat, Microsat, and RISAT spacecraft have likewise been redesignated with EOS numbers.
GSLV Mk. II
EOS-03 launched aboard ISRO’s Geosynchronous Satellite Launch Vehicle Mk. II (GSLV Mk. II) rocket — an evolved version of the original GSLV design which itself was an offshoot of the smaller Polar Satellite Launch Vehicle (PSLV).
The GSLV that performed Thursday’s launch was designated GSLV F10 and marked the 14th flight of the GSLV Mk. I and II family, which shares the same first and second stages with the PSLV but uses four liquid-fueled boosters which remain attached for the duration of first stage flight.
The GSLV Mk. II’s first stage therefore consists of an S139 solid rocket motor core with four L40H liquid-fueled boosters — each using a single Vikas 2 engine — clustered around it.
The second stage, designated GS2 (GL40), is liquid-fueled and uses a single Vikas 4 engine – a license-built derivative of the French Viking from the Ariane program that burns dimethylhydrazine and dinitrogen tetroxide.
| Time | Event | Velocity (inertial) |
| T-4.8 secs | Liquid-fueled booster ignition | N/A |
| T0 | S139 solid motor ignition; LIFTOFF | N/A |
| T+2 mins 29 secs | Liquid-fueled booster shutdown | 2,689.3 m/s |
| T+2 mins 30 secs | 2nd stage ignition | 2,689.9 m/s |
| T+2 mins 31 secs | 1st stage separation | 2,688.8 m/s |
| T+3 mins 55 secs | Payload fairing separation | 3,813.7 m/s |
| T+4 mins 51 secs | 2nd stage shutdown | 5,187.6 m/s |
| T+4 mins 55 secs | 2nd stage separation | 5,206.5 m/s |
| T+4 mins 56 secs | 3rd stage ignition | 5,206.0 m/s |
| T+18 mins 24 secs | 3rd stage shutdown | 10,204.9 m/s |
| T+18 mins 29 secs | Null thrust | 10,204.6 m/s |
| T+18 mins 39 secs | EOS-03 separation | 10,196.1 m/s |
This particular GSLV mission used the CUS-15 cryogenic third stage which uses a single CE-7.5 engine burning liquid hydrogen and liquid oxygen. This stage was responsible for completing the insertion of EOS-03 into the proper geosynchronous transfer orbit, which it failed to do.
The payload fairing for this mission debuted a new configuration with an ogive shape and a 4 meter diameter to allow larger satellites to be launched by the GSLV.
The GSLV can utilize two launch complexes at the Satish Dhawan Space Centre on Sriharikota island: First Launch Pad and Second Launch Pad. While both pads are available, all GSLV launches since 2006 have occurred from the second pad.
Launch delays
The EOS-03 satellite — then still called GISAT-1 — had been due to launch early last year, with the rocket fully integrated and rolled to its launch pad in preparation for a March 5, 2020 liftoff. A technical problem arose which led to the launch being delayed and the rocket rolled back to the assembly building.
While the issue was being investigated, the coronavirus pandemic took hold, and ISRO suspended operations. The satellite was demated from the GSLV and moved back to its preparation building and launch was eventually rescheduled for March 2021, later slipping into April and then May as voltage fluctuations were detected in the satellite.
The May launch attempt coincided with a resurgence of COVID-19 cases in India, and further delays were necessary as all available oxygen production — including at ISRO’s facilities — was diverted to medical applications. With cases now down from their peak in May and hospital oxygen supplies under less pressure, ISRO has been able to produce the liquid oxygen GSLV will use during its ascent on Thursday.
India’s space program has been hit hard by the events of the last two years, with the country having made only two orbital launches in 2020, down from six in 2019. Thursday’s launch will be India’s second of 2021 and the first since January. The country’s next orbital launch is currently expected in October, with a PSLV rocket deploying the EOS-06 satellite (formerly Oceansat-3).
(Lead image: The GSLV Mk. II with EOS-03 rolls out to Second Launch Pad. Credit: ISRO)