Chandrayaan-2 lift-off on July 22, 2019
All eyes are now set on the launch at 2.43 p.m. on July 22 when the GSLV-Mk III will soar into the sky with the Chandrayaan-2 spacecraft, the lander and the rover.
A plethora of activities is getting into top gear at the second launch pad at India’s spaceport at Sriharikota for the lift-off of the Geo-synchronous Satellite Launch Vehicle – Mark III (GSLV-Mk III) at 2.43 p.m. on July 22, 2019. The rocket carries on board a spacecraft called Chandrayaan-2 and it is a mission to the moon. It is the most ambitious and technologically challenging mission that the Indian Space Research Organisation (ISRO) has undertaken because it involves not only putting a spacecraft into an orbit around the moon but soft-landing a big contraption called the lander on the South Pole of the moon. From the lander will emerge a rover, which will roll down a ramp on its six wheels. The six-foot long rover, which is a robotic vehicle, will wander about on the surface of the moon up to a maximum distance of 500 metres.
“Everything is fine and we are going ahead [with the launch on July 22]” declared S. Ramakrishnan, former Director, Vikram Sarabhai Space Centre (VSSC), Thumba, Thiruvananthapuram, which built the GSLV-Mk III. He exuded confidence as he spoke over the phone to this reporter around 8.10 p.m. on July 20 from the Thiruvananthapuram airport where he was waiting to board a flight to Chennai to drive to Sriharikota, about 100 km away. The Mission Readiness Review (MRR) team had met at Sriharikota on July 20th evening and given the “go-ahead” for the lift-off the GSLV-Mk III to take place at 2.43 p.m. on July 22. The 20-hour count-down will begin at 6.43 p.m. on July 21.
2 Expeditions. 110 years Apart.— ISRO (@isro) June 18, 2019
Read on to find out more... pic.twitter.com/e2CHWrYpxD
The launch was to originally take place at 2.51 a.m. on July 15. There was an air of expectancy at the state-of-the-art, saucer-shaped Mission Control Centre (MCC) at Sriharikota. President Ram Nath Kovind was present at the MCC and was looking forward to the launch. However, a technical snag developed in the third, topmost cryogenic stage of the rocket about 56 minutes before the GSLV-Mk III was to soar into the sky with the spacecraft, the lander and the rover on board. Helium gas started leaking from one of the metallic bottles in the cryogenic stage after the propellant tanks had been filled with the cryogenic propellants – liquid oxygen and liquid hydrogen – at extremely low temperatures. (A cryogenic engine uses liquid oxygen as oxidiser at minus 240 degrees Celsius and liquid hydrogen as fuel at minus 265 deg. C).
As the leak continued and the pressure did not hold in the engine chamber, “count-down called off” rang a voice from the MCC. The helium gas was meant to maintain the pressure in the cryogenic engine chamber. With the helium gas leaking, “pressure was not holding”, an ISRO top brass said. This meant that control valves, the pneumatic systems, the hydraulic systems and so on would not work. The rocket might go up but it would put the spacecraft into a much lower orbit than targeted. So ISRO decided to scrub the launch. “The launch called off” came the announcement a couple of minutes later from the MCC.
For several thousands of people gathered from midnight at the newly-built Viewers’ Gallery just outside the spindle-shaped Sriharikota island, the big media contingent present at the Media Centre inside Sriharikota and millions of space aficionados across the country, it was a big let-down. Speculation swirled that ISRO could aim for a launch only in September because a favourable launch-slot was available only then.
But ISRO made a remarkable come-back. And quickly, too. It set up a committee to investigate the cause of the helium gas leak from one of the metal bottles. The propellant tanks in the cryogenic chamber were first safely drained of their 25 tonnes of highly inflammable liquid oxygen and liquid hydrogen. Yet, it was not easy to approach the gigantic, three stage rocket, 44-metres long and weighing 640 tonnes.
Although there was access to the 16-storey tall vehicle, with platforms at various levels, ISRO rocket engineers could not rush to the vehicle. They waited for the hardware temperature to come down to the ambient temperature. Platforms were then deployed to enable the engineers to approach the vehicle and they investigated the problem in the cryogenic stage, using the platform at that level. All high pressure gas systems were removed and it was confirmed that helium gas had indeed leaked from one of the manual joints in the bottle. The joint was tightened and the leak stemmed.
Chandrayaan 2 is ready to take a billion dreams to the Moon — now stronger than ever before! Join us for the launch on Monday — 22 July, 2019 — at 2:43 PM IST.— ISRO (@isro) July 18, 2019
#Chandrayaan2 #GSLVMkIII #ISRO pic.twitter.com/4ybFcHNkq6
Ramakrishnan, who had played an important role in designing and building the GSLV-Mk III, said: “We knew that the problem was not very complex because these kinds of leaks occur in many vehicles. Leaks happen in launch vehicles which use liquid propellants. There was a hydrogen leak in the U.S. space shuttle. We identified the problem [in our vehicle] and corrected it… Everything is fine and we are going ahead [with the launch].”
Eyes are now set on the launch at 2.43 p.m. on July 22 when the GSLV-Mk III will soar into the sky with the Chandrayaan-2 spacecraft, the lander and the rover. These three together constitute what is called the composite module, which sits on top of the cryogenic stage. The composite module is surrounded by a towering heat-shield to protect it from turbulence and high temperature when the rocket knives through the earth’s atmosphere. The lander has been named Vikram after the late Vikram Sarabhai, the charismatic founder of India’s space programme. The rover has been christened Pragyaan, which is a Sanskrit word for “knowledge” or “wisdom.”
While the lander sits on top of the spacecraft, Pragyaan is inside the lander. The spacecraft, the lander and the rover carry a total of 14 scientific payloads for studying the composition of the lunar soil, to look for various minerals, to search for buried water-ice on the moon, to investigate its exosphere, investigate the lunar quakes, that is, its seismic activity and so on.
A significant feature of the mission is that the lander will touch down on the South Polar region of the moon, where even the U.S., Russia and China have not dared to go so far.
Here's some exclusive, behind-the-scenes footage of the mission's various components coming together - https://t.co/baOMowvWHa— ISRO (@isro) July 14, 2019
Tell us what you think about it in the comments below. #Chandrayaan2 #GSLVMkIII #ISRO pic.twitter.com/Kguy33p2C1
About 17 minutes after the lift-off, the cryogenic stage of the GSLV-Mk III will inject the composite module weighing 3.8 tonnes into an initial earth-parking orbit with an apogee of 39,120 km and a perigee of 170 km. In the next 16 days, the propulsion system on board the spacecraft/orbiter will fire five times. These burns will enable the composite module to perform five manoeuvres and the module will reach an orbit of 150 km by 1,41,000 km. Then the propulsion system on board the composite module will ignite again and put it on a trajectory towards the moon. It will travel towards the moon for the next five days and reach the vicinity of the moon. Then there will be more firings of the propulsion system on board the composite module, which will be finally inserted into a circular orbit at a height of 100 km around the moon. Later, the lander Vikram will detach itself from the spacecraft.
On September 7, after the lander comes down to a height of 30 km above the moon, it will descend slowly in a controlled manner and gently touch down at a spot on the moon’s south Pole. The sensors aboard the lander will decide where it should land on its four legs – in an area where there are no boulders, craters or slopes. It will take 15 minutes for the lander to descend from an altitude of 30 km above the moon and reach the lunar surface. About 40 events will take place in those 15 minutes. Computers on board Vikram will decide what should be the velocity of its descent at various stages of those 15 minutes. After a wait of four hours, a door on the lander will open and a ramp will fan out. The rover Pragyaan will emerge from the lander, slide down the ramp and drive around on the lunar surface.
K. Sivan, ISRO Chairman, told a press conference in Bengaluru on June 12, that the 15 minutes that the lander would take to touch down softly on the lunar surface would constitute “the most terrifying moments not only for the people in India but for all Indians.” He added, “These 15 minutes will form the most complex mission that ISRO has ever undertaken.” What is significant is that ISRO has developed throttleable engines to control the descent of Vikram and make it land smoothly. The throttleable engines were “a new [technology] development for us,” Sivan said.
What role does industry partnership play in the progress of space research? Listen to ISRO Chairman K Sivan's message to find out! https://t.co/5SxaKb5PLw #Chandrayaan2 #GSLVMkIII #ISRO pic.twitter.com/X1mugKM3Vn— ISRO (@isro) July 14, 2019
While Chandrayaan-2 spacecraft weighs 2.4 tonnes and has eight science instruments including cameras to take pictures of the moon, Vikram weighs 1.4 tonnes and has four scientific payloads. One of them is a payload from NASA to measure the distance from Vikram to the earth. The rover has two instruments. While the lifespan of the spacecraft is one year, Vikram and Pragyaan will last for one lunar day or 14 earth days.
Chandrayaan-2 project is totally indigenous. The GSLV-Mk III, the spacecraft, the lander and the rover have all been built in ISRO facilities. Thirteen out of 14 scientific instruments have been developed in ISRO facilities.
About 500 industries across India have contributed to the making of the GSLV-Mk III. Another 120 including industries, academic institutions and research facilities were involved in making the hardware and software packages for the composite module. Dr. Sivan acknowledged their role when he said, “It is not only ISRO’s mission but the entire country’s programme. The entire country has contributed to it and is looking for new science from it. The whole nation will benefit from the Chandrayaan-2 programme.”
Chandrayaan-2 mission is India’s second moon shot. ISRO took its first aim at the moon in October 2008 when a Polar Satellite Launch Vehicle lifted off from Sriharikota with the spacecraft Chandrayaan-1 on board. The spacecraft was later put into orbit around the moon. As Dr. Sivan noted, “the greatest achievement” of Chandrayaan-1 was its discovery of water-ice on the moon. The mission entailed crash-landing a device called the Moon Impact Probe (MIP) on the lunar surface. But Chandrayaan-2 is much more complex and technologically audacious because the lander Vikram has to touch down on the moon and the rover Pragyaan has to gallivant on the lunar soil.
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