India Takes Yet Another Step Toward Sending Humans To The Moon – OpEd

By Devinder Kumar

The Indian Space Research Organisation (ISRO)—which has been working on key technologies to realise its vision of setting up a space station by 2035 and sending humans to the Moon by 2040—on January 16 morning successfully demonstrated space docking, or the joining of two fast-moving satellites in space.

Two small 220-kg satellites were brought within a distance of three metres from each other in orbit, their extended ring was joined with each other, retracted, and locked in space. ISRO also demonstrated giving commands to the two satellites as one composite object.

The successful docking makes India the fourth country in the world—after the United States, Russia, and China—to have this capability. This capability is necessary not only for carrying out missions that require heavy spacecraft that a single launch vehicle may not be capable of lifting off with, but also for carrying crew and supplies to it.

United States NASA’s Gemini VIII became the first spacecraft in 1966 to dock with the target vehicle Agena. Gemini VIII was a crewed mission orbiting the Earth, commanded by Neil Armstrong, who in 1969 became the first human to set foot on the Moon.

While the US mission had astronauts on board to steer the spacecraft, the Soviet Union in 1967 demonstrated the first uncrewed, automated docking of the Kosmos 186 and Kosmos 188 spacecraft.

China demonstrated its docking capability in 2011, when the unmanned Shenzhou 8 spacecraft docked with the Tiangong 1 space laboratory. A year later, China demonstrated its first crewed space docking, when the astronauts manually joined its Shenzhou 9 spacecraft to the same space laboratory.

India’s science minister Dr Jitendra Singh posted: “Spadex has accomplished the unbelievable … and it is all (using the) indigenous Bharatiya Docking System. This paves the way for smooth conduct of ambitious future missions including the Bharatiya Antriksha Station, Chandrayaan 4 and Gaganyaan.”

The first launch will have four of the five modules—the propulsion module will carry the spacecraft from Earth orbit to the Moon orbit, from where the lander and ascender modules will go to the lunar surface and collect the samples. The ascender module will then hop up with the samples, and dock with the transfer module in the lunar orbit.

This transfer module will carry back the samples to the Earth orbit where it will dock with a re-entry module that will be launched separately. The module will be designed to withstand the heat of entering the Earth’s atmosphere.

In preparation for this mission, ISRO carried out a “hop experiment” towards the end of the Chandrayaan-3 mission. A human mission to the Moon is likely to follow a similar plan.

Giving command to the satellites as a single composite object

ISRO carried out a series of manoeuvres to progressively bring the SDX01 or “Chaser” satellite close to SDX02, or the “Target” satellite. The satellites were allowed to drift close, and then their positions were held at around 5 km, 1.5 km, 500 m, 225 m, 15 m, and 3 m, before finally being joined together.

India’s space agency has demonstrated giving command to the satellites as a single composite object. In the coming days, it will demonstrate sharing of electrical power between the two satellites. Once that is complete, ISRO will demonstrate “undocking”, during which the satellites will separate and drift away to carry out their respective experiments over the two years of the mission’s life.

The docking experiment was initially slated for January 7, but was postponed after identifying an abort scenario. More simulations were carried out on the ground to improve the accuracy of docking. The docking could not take place on January 9 either, with the satellites drifting more than anticipated during a manoeuvre to reduce the distance to 225 metres on the previous day.

After this, the satellites drifted nearly 5 km apart, and manoeuvres to bring them closer were restarted. Early on January 12 morning, the satellites were brought closer together, and this time they reached the hold point of 3 metres before being moved away to a safe distance. ISRO said that the data were being analysed before the actual docking could be conducted.

*This report is based on an article in the Indian Express, written by Anonna Dutt.