NEW DELHI: In another spatial milestone, Indian Space Research Organisation’s Chandrayaan-2 orbiter has successfully completed a year around the Moon. In this period, the orbiter has not only done 4,400 orbits around the Earth’s only natural satellite but also made several key findings. Though the Vikram lander’s operation was not successful, Chandrayaan’s orbiter, loaded with eight scientific instruments, is performing well and there is adequate fuel on it for it to remain operational for about seven years.
The Chandrayaan-2 mission was launched on July 22, 2019 and the lunarcraft was inserted into the Moon’s orbit on August 20 exactly a year ago. The orbiter is currently being maintained at 100 +/- 25 km polar orbit with regular orbit maintenance (OM) manoeuvres. So far, 17 OMs have been carried out since achieving the 100-km lunar orbit on September 24, 2019, an Isro statement said.
The orbiter high resolution camera (OHRC) on board the craft has acquired 22 images of the lunar surface covering nearly 1,056 sq km area. It is also used to characterise landing sites for future missions. Another camera for terrain mapping (TMC-2) acquired images during 220 orbits covering nearly 4 million sq km area and generated digital elevation models and ortho-images (computer-generated image of an aerial photograph without distortions) of the lunar surface and various craters, including the Sarabhai crater.
“On 29th of May, the Sun flared to a level of C9.3, the second strongest flare of 2020, and X-ray spectrometer (CLASS) on board the orbiter caught secondary X-rays from fluorescence on the moon as it flew over the rugged southern farside highlands. The X-ray spectrum showed direct and clear spectral signatures of major refractory elements (aluminium and calcium) from the highland region with additional evidence for lower amounts of magnesium and Iron,” Isro said.
“The far side hidden from the Earth’s view is quite different from the side visible from our planet. Most of the lunar mare volcanism is confined to the nearside. All of the returned samples collected by the American Apollo missions are from the nearside equatorial region, which serve as a calibration standard for remote sensing measurements. However, we know today that the highland compositions are more diverse than what is represented in the returned samples. X-ray spectroscopy being one of the most direct approaches, CLASS delivers the promise of higher spatial resolution global maps for major elements on the lunar surface, the first of its kind,” it said.
The Dual frequency Synthetic Aperture Radar (DFSAR), which was to do the first full polarimetric measurements of permanently shadowed regions, has also been sending data. “First L-band observation of the Moon along with the S-band, provides better identification of sub-surface water,” Isro said. Besides them, the Imaging Infrared Spectrometer (IIRS), Solar X-ray Monitor (XSM), Chandra’s Atmospheric Composition Explorer – 2 (CHACE-2) and the Dual Frequency Radio Science Experiment (DFRS) payloads have also been sending various images and data
Like the various achievements of Chandrayaan-2, the country’s first lunar mission Chandrayaan-1 mission had also won laurels from around the world for establishing the extensive presence of surface water and the indication of subsurface polar water-ice deposits, arguing for more focused studies on the extent of water on the surface, below the surface and in the tenuous lunar exosphere, to address the true origin and availability of water on the Moon.
The Moon provides the best linkage to understand Earth’s early history and offers an undisturbed record of the inner solar system environment. It could also be a base for future human space exploration of the solar system and a unique laboratory for fundamental physics investigations.