The Chandrayaan 2 mission
The Chandrayaan 2 mission will be classified as a partial success. The most ambitious component, a soft landing in an unknown, unexamined location, followed by exploration through a mobile vehicle, has failed, for reasons unknown at the time of writing. But the orbiter works well and will continue to carry out its scientific experiments.
In many ways, a soft landing on the moon is a very difficult task. Any soft landing requires that the landing module gradually lose speed with respect to the moon as it approaches the surface. This requires a complicated calculation since the moon has much lower gravity and there is no atmosphere to speak.
That is only part of the challenge. Much of the moon is covered with a thick layer of dust and it is not easy to discover how deep that dust is. A landing module could sink meters below the surface. Choosing a place where there is firm ground is, in itself, quite difficult.
It is even more difficult to do this on the “far side” unexplored. The ISRO mission deliberately chose a place not studied by previous missions. Think of the moon as a ball, which orbits the Earth once every 27.3 days. That ball also spins, spinning in almost exactly the same period of 27 days. This tidal block means that it always presents the same side to an Earth observer and approximately 59 percent of the moon can be observed from Earth.
The Chandrayaan 2 mission was aimed at landing at the Lunar South Pole on the opposite side.
That is an area that we know very little about. This is precisely why he was chosen. The plan was for the Vikram Lander-Pragyan Rover combination to examine local rocks, study their chemical composition and, above all, look for water.
The latest news before the communication link broke showed that Vikram was moving at about 50 meters / second at 2.1 km above the surface. A successful landing as planned would have required a speed reduction of approximately 2 meters / second in the final landing.
The first phase – “sharp braking” – to reduce the speed of 1680 m / s seemed to be going well. But the next phase of fine braking to reduce it to almost ground level and reduce the speed to 2 m / sec is when the communication is cut. The breakdown suggests that this phase was not completed as scheduled and the landing module crashed.
The orbiter can see Vikram at some time or perhaps, the data analysis sheds light on what happened. ISRO must return to the drawing board and discover what went wrong before making another attempt at a lunar mission.Surely there will be the next attempt at some point, although we cannot say when. Meanwhile, the orbiter continues to orbit the moon in an almost circular orbit about 100 km above the surface. During the next year, the orbiter will carry out the surveys and experiments for which it was designed.
The orbiter has eight scientific instruments (“payloads”) that will be used to map the lunar surface and study its atmosphere. This includes terrain mapping cameras, an X-ray spectrometer to search for chemical elements, an X-ray monitor to study solar radiation, high-resolution cameras to zoom in and map the surface, an infrared spectrometer to search for water and minerals, radar For mapping depth and high resolution, a tool for mapping the composition of the exosphere (upper atmosphere) and an instrument that uses double frequency signals to study electron density in the lunar ionosphere. This set of experiments will undoubtedly add to the knowledge of the largest satellite on Earth. The orbiter has a designed lifespan of one year, so we should see the updates for a while.
The Vikram landing module had a seismometer designed to record lunar earthquakes, a meter to measure the thermal properties of the lunar surface and other instruments to map the atmosphere (which is very thin), as well as a mirror instrument (a laser reflector) that is measured very accurately the distance between the Earth and the Moon. Unfortunately, they will have to be discarded.
It is important to keep in mind that the odds were against someone achieving a soft landing on the first attempt. Only three nations have achieved soft lunar landings and an Israeli mission failed earlier this year. ISRO should be proud of what it has accomplished and this will surely help the next mission.