ISRO's tender notice reveals interesting new insight into Gaganyaan launch in 2021

ISRO's tender notice share details on two rocket stages of Gaganyaan launch vehicle- GSLV Mk III

The year 2021 is still a few light-years away from reaching its point, but the Indian Space Research Organisation (ISRO) has been steadily moving ahead to complete its first manned space mission ‘Gaganyaan’ on schedule i.e., December 2021.

The Gaganyaan will be placed in a low earth orbit of ‘300-400 km,’ and it will be launched by GSLV Mk III, the three-stage heavy-lift launch vehicle.

Rpresentational image of GSAT-7A, a military communications satellite

Representational image of GSAT-7A, a military communications satellite

While ISRO recently shared insights that its unmanned test missions for Gaganyaan will carry humanoid robot, fresh new details about the human spaceflight programme has now been tabled.

The details as spotted by The Wire in an ISRO tender notice are said to be available on the e-hub since August 2017. The tender notice that includes details of new stages for its GSLV MK III launch vehicle has invited quotations for a host of infrastructure upgrades that will prepare its second launch pad at Satish Dhawan Space Centre, Sriharikota to support the human spaceflight and heavier satellites. As per the report, the last date for submitting proposals is listed 20 February.

GSLV Mk III is a three-stage heavylift launch vehicle. Image: The Wire

GSLV Mk III is a three-stage heavylift launch vehicle. Image: The Wire

While the ‘engineering aspects’ of Gaganyaan includes the launch vehicle, crew module, and service module, latest details on the development reveal two rocket stages- SC120 and SC200. For those uninitiated, GSLV Mk III is a three-stage heavy lift vehicle that has two solid motor strap-ons (S200), a liquid propellant core stage and a cryogenic stage.

As per the latest report, the first stage with two solid motor strap-ons comprises two boosters called S200, which are attached on both sides of the rocket. The second stage with liquid propellant is powered by the L110 stage, combusted by a pair of Vikas 2 engines. The cryogenic stage is said to be powered by a cryogenic engine, C20. The SC in ‘SC120/200’ which denotes semi-cryogenic, is said to be the alternatives for GSLV Mk III’s second stage.

The Wire’s report further citing a discussion on Reddit suggested that ‘adapting’ the three-stage heavy lift vehicle will require tweaks and moderation from the original version in order to use it. The GSLV Mk III with the L110 stage can currently lift up to 4,000 kg, however, for the human spaceflight mission, the rocket is expected to lift over 5,000 kg.

The report managed to obtain a technical document that revealed the dimension and weight of the SC120 stage. The technical document noted that the SC120 will be 4 m wide, 17.29 m tall and weigh 11,500 kg. The semi-cryogenic stage is said to carry liquefied oxygen and ‘kerolox (RP-1),’ a highly refined form of kerosene used in Elon Musk’s SpaceX Flacon 9.

The RP-1 is denser than metholox and hydrolox and it requires less tank volume for storage thereby reducing the inert mass of the rocket. But while kerolox aka RP-1 is a better coolant it requires refurbishing of the entire engine after the operation, given that kerolox produces carbon deposits ‘over the nozzle wall’ as it ignites. The Wire notes that for the ‘crewed spaceflight’ programme, it will require a launch pad that will be able to support intense workload of Mk III, along with the logistical requirements for transport and loading different fuels.

To one of many successful missions, ISRO last week launched Microsat-R, a military satellite onboard its Polar rocket PSLV C44 and a student-built Kalamsat satellite. The PSLV took off from the first launch pad of Satish Dhawan Space Centre, Sriharikota. Notably, this is the first time that ISRO had used the last stage of the rocket as a platform to perform experiments in space.

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