The ISRO’s Space Applications Centre (SAC) at Ahmedabad, which is designing the “eyes and ears” of Chandrayaan-2, has targeted to deliver all the payloads for the lunar mission by the end of 2015, official sources said. This includes three major payloads and a crucial set of sensors and communication equipment that will be fitted on to the orbiter, lander and the rover.
“There are three parts of the Chandrayaan-2 mission: the lunar orbiter, lander and the rover. We at SAC are developing communication equipment that will help the rover interact with the lander while moving around on the moon’s surface. The lander, in turn, can communicate to the orbiter and the orbiter can beam back the data to the earth. So in short we are developing the eyes and ears of Chandrayaan-2,” said Tapan Misra, the director of SAC while talking to The Indian Express.
ISRO has set 2017-18 as a target for launching Chandrayaan-2, which is being developed as an “indigenous” mission. “The preliminary design review is over and the flight models are under fabrication. We will be delivering the payload by the end of this year or at the beginning of next year,” Misra added. SAC is developing three major payloads namely the Terrain Mapping Camera-2 (TMC-2), Imaging Infra-Red Spectrometer (IIRS) and L&S Band Synthetic Aperture Radar (L&S-band SAR). All these three payloads will be part of the orbiter that will encircle the moon.
Most of the equipment being developed at SAC are advanced versions of those on Chandrayaan-1 which was lost mid-way during the mission in 2009. For instance, the TMC-1 that had accompanied Chandrayaan-1 mission had mapped only 45 percent of the moon’s surface. TMC-2, which will be only two-third the weight of it’s predecessor, will be mapping the remaining surface and will be creating a three-dimensional map of the lunar surface.
Meanwhile, the L&S-Band SAR will be the first indigenously developed microwave sensor to be flown in a planetary mission. This equipment will not only help detect water-ice, but it will also have the capability to estimate the quantum of water present in a particular area. It will also map polar regions and lunar craters.
The IIRS is also an advanced version to the spectrometers – Hyper Spectral Imager (of SAC), Moon Mineralogy Mapper (NASA) and Near Infrared Spectrometer (Germany) – flown onboard the Chandrayaan-1. Such an instrument which can also look at the permanently shadowed areas of polar regions of the moon is being development for the first time in ISRO.
The most challenging part of the Chandrayaan-2 mission will be the soft landing of the lander on the lunar surface. “SAC is developing all the sensors to provide the lander with real-time information for navigation need for a safe descent on the moon’s surface,” Misra remarked.
The sensors being developed are Orbiter High Resolution Camera (OHRC), Ka-band Altimeter, Lander Position Detection Camera (LPDC) and Lander Hazard Detection and Avoidance Cameras (LHDAC). While the OHRC onboard the orbiter will image the landing site and determine the exact descent point before the lander is ejected from the composite spacecraft, the other three sensors will guide the lander to the descent point.
SAC is also developing a HD video camera for both the lander and the rover. “The equipment on board the lander and the rover will have a mission life of just 14-15 days. The extreme temperatures on the moon will eventually destroy them,” Misra said adding that the equipment developed by SAC for the lander and the rover can withstand temperatures ranging between a freezing minus 30 degrees to a high of 70 degrees.
Apart from SAC, the Ahmedabad-based Physical Research Laboratory (PRL) will is also developing two payloads of Chandrayaan-2. This includes a X-Ray Solar monitor that will part of the orbiter and will observe the x-rays emitted from the Sun. PRL is also developing a rover payload called the Alpha Particle X-Ray Spectrometer that will determine the elemental composition (Mg, Al, Si, K, Ca, TiFe) of lunar soil and rocks around the lunar landing site.
Both SAC and PRL will be sending five of the 12 major payloads that will accompany Chandrayaan-2.