Chandrayan-2 successfully entered into an elliptical orbit around the moon on Tuesday, as India officially "reached the moon" for the second time, 11 years after its first mission to find water on the lunar surface.
"Heart of Tuesday" Replacement of the move was described as a "highlight" by the chairman of the Indian Space Research Organization (ISRO) K Sivan.
The successful soft landing, scheduled for 1.55pm on September 7, will make the Indian mission the first land near the south pole of the moon 70 degrees south of the equator.
In addition, India will become the fourth country after the US, the former USSR and China to land on the lunar surface.
“The unique requirement of Chandrayan-2's mission, which no other country has ever had, is to achieve a 90-degree moon orbit. This is to ensure that the spacecraft is able to land near the south pole of the moon. The transulunary injection maneuver on August 1
All other lunar landings so far have occurred in regions about 30 to 40 degrees from the lunar equator.
Entering the lunar orbit
It was a very precise trans-lunar injection and deployment of lunar orbit maneuvers to ensure that the spacecraft reached the intended inclination, Sivan said. "To give you a perspective, for a spacecraft moving at 10.9 km / second, a deviation of 10 cm per second during a transpellar injection would change the inclination in the moon's orbit by 7 degrees," he explained. he.
At 9.02am ISRO scientists launched a space shuttle propulsion system in 1738 seconds (nearly 29 minutes) to achieve a highly elliptical 114×18.072 km orbit and an 88 degree incline. In four maneuvers, the orbit will be reduced to a circular 100×100 km over the next 12 days and a 90 degree incline will be reached.
"In 30 minutes today our heart is almost stopping," Sivan said.  A translucent injection maneuver on August 14 threw the Chandrayan-2 (Orbiter, Lander and Rover) composite module on its way to the moon at a speed of 10.9 km per second.
This maneuver increased the apogee, or point of orbit farthest from Earth, to 418,000 km. On August 19, around 3:00 PM, as the Moon approached the spacecraft as it returned from its climax, Chandrayan-2 entered the Moon's sphere of influence.
“After that, Chandrayan-2 began to gain speed under the influence of the gravity of the moon. To ensure that it enters orbit around the moon, the maneuver reduces speeds from 2.4 km per second to 2.1 km per second, "says Sivan.
In the past, lunar missions, such as the US Ranger 3 in 1962 and Explorer 33 in 1966, and the USSR Moon 6 in 1965 failed and flew past the moon at that time.
Separation and Landing
The next major phase of the mission will be on September 2, when Lander-Rover detaches from Orbiter.
On September 3, there will be a small maneuver to check the system, after which the space agency will check various parameters of Lander. "After we confirm that the system is OK on September 7, at 1.40 hours the power will start and at 1.55 hours the land will go down," Sivan said.
"The landing will be a terrifying moment for us. So far, we have not operated the onboard systems, especially the propulsion system. This is the phase, including the power down, that we will do for the first time until we have introduced lunar orbit once." , he added, noting that only 37% of the landing attempts were successful.
Earlier this year, the Israeli Beresheet mission crashed on the moon's surface due to engine damage.
"Landing site [on September 7] will be selected autonomously by Lander-Rover as a comparison The main considerations will be that the slope of the landing site should be less than 12 degrees and without stones to prevent the destruction of land, "says Sivan.
Lander-Rover is expected to land in a high plane between two craters, Manzinus C and Simpelius N. This region was chosen because the craters here have been untouched by sunlight for billions of years, offering unsettling records for the creation of the solar system. Permanent shade craters are also thought to hold 100 million tonnes of water.
The location and availability of resources such as hydrogen, ammonia, sodium, methane, mercury and silver at the South Pole also make it an ideal pit for stopping future space exploration missions
"This is the first time an Indian mission will land at terrestrial surface and also at the South Pole of the moon. Isro did not want to go into an area that has already been explored, as it does not contribute to our scientific understanding, "says Rajeswari Rajagopalan, Head of the Nuclear and Space Policy Initiative, Observer Observation Foundation.
" From here on, ours space The program will try more complex missions, but it remains a very complex mission and we have to wait and see what happens on the landing day, "she added.
August 21, 2019 12:10 AM IST