Chandrayaan - 2 New heights in Space Tech.

Chandrayaan 2 is India’s second moon mission. Taking a step further in lunar exploration ISRO’s Chandrayaan 2 intends to do satiate the curiosity even more by being able to send more scientific instruments for study of lunar surface. The mission is to carry Orbiter Craft Module OC and Lander Craft Module LC. The Lander Craft Module named Vikram is supposed to ferry a rover named Pragyan that would attempt to perform in-situ chemical analysis of lunar soil present at the south pole of moon. It would expand the technologies from Chandrayaan 1. This mission also intends to demonstrate newer technologies for future interplanetary missions. The OC will also carry scientific payload that would enhance the scientific objectives of Chandrayaan 1 with improved resolution. Both the OC and LC would be carried in a single launch attached to each other their composite mass is stated as 3320 kgs as of latest. The OC would have a life of 1 Earth Year and the LC and Rover would have lives of just whatever they could do until the sun sets. Both LC and Rover draw their energy from solar panels and without availability of Sun they won’t work. A usual day on moon is equivalent to 14 Earth Days so probably that is how long the rover and LC would live.

Mission

The Chandrayaan 2 mission would begin with the launch of the 3850 kgs co-joined Oribiter Craft and Lander Craft via a GSLV mk3 Launch Vehicle. As GSLV mk3 with an upper stage cryogenic engine has validated itself being a reliable vehicle to launch heavier payloads. The GSLV mk3 would place Chandrayaan 2 spacecraft in Earth Parking Orbit of 170 km Apogee and 19,998 km Perigee. Later on orbit raising burns would substantially increase the Perigee until the velocity of the craft is substantial enough to hurl it into Lunar Transfer Trajectory. After which it would transferred to Lunar orbit and orbit reducing maneuvers would be done to finally stabilise the Chandu 2 into a circular polar orbit of 100km. This has been described as 'science orbit’ . After acheiveing this orbit the second phase would begin where suitable landing site and timing would be matched with previously decided ones and the LC would be separated.

Here the LC would de-orbit and position itself in an orbit of 30km perigee , and start it's rough braking phase while decending towards the Moon. The LC would fire it's thrusters to manage the approach speeds and would come closer to 7 kms from Lunar Ground. This would be followed by an autonomous adjustment of attitude. LC would take photos and autonomously decide it's landing site and trajectory to approach it. The LC would stabilise itself vertically 100 metres above the intended landing site and with the help of it's onboard attitude control thrusters and four main thrusters slowly decend down. It's hazard avoidance system and altitude sensors would ensure prevention of any external damage to the craft. The landing legs would be deployed during this phase. The decend would continue until LC is 2 m above the surface, after which the thrusters would shut themselves off. And the landing legs would absorb the shock of landing while lander falls from 2 m above. Immidietly the rover would be deployed.

The Rover is supposed to move around for 14 days and conduct chemical analysis of Moon's soil. Using it's six wheels and traction control the Rover would analyse samples at different spots across the surface, while constantly communicating with the LC, The LC with the OC and the OC communicating with Earth. The OC would perform varied experiments further enhancing those done by Chandrayaan 1. While LC would judge Moon's crust and sesmic activity along with taking photos of areas around.

Oribiter Craft Module OC

The Orbiter has similar configuration as that of Chandrayaan 1. A box shaped craft having an internal cylinder consisting of fuel tank and main thruster at the bottom. Difference is that their was Moon Impact Probe on top of Chandrayaan 1 while the faring on the top of Chandrayaan 2 seems grossly revised in terms of strength so as to sustain the weight of LC. The top portion would attached to LC during launch and both OC and LC would separate only when they would be in lunar orbit. Their are attitude control thrusters and scientific payloads spread over the three sides of the outer surface while on the fourth side what appears to be is a deployable Solar Panel just like that of Chandrayaan 1.

As an evolution to what Chandrayaan 1 did, the scientific payloads on Chandu 2 are evolutionary. Their are total 8 payloads on it.

1 Terrain Mapping Camera 2 :- To prepare a detailed 3D map of Moon's surface, using 2 cameras it is evolved from the TMC of Chandrayaan 1.

2 CLASS Collimated Large Array Soft X-ray Spectrometer :- It would map the abundance of major rock forming elements like Magnesium, Aluminium, Silicon, Cadmium, Titanium and Iron on moon's surface.

3 XSM X-Ray Solar Monitor :- It intends to observe the X rays emitted from the Sun’s corona which would assist the CLASS. As CLASS is a passive sensor.

4 OHRC Oribiter High Resolution Camera :- The job of this Camera is to catch high resolution images of landing site prior to landing.

5 IIRS Imaging Infrared Spectrometer :- This is the coolest thing on the module because this is going to study presence of hydroxyl (OH), Water H2O and other minerals in the polar regions of Moon.

6 SAR Synthetic Aperture Radar :- Its work is to map the geographical features like craters especially at the polar surfaces.

7 CHACE 2 Chandra's Atmospheric Composition Explorer 2 :- It is a neutral mass spectrometer that would carry out study of Moon's exosphere.

8 RAMBHA Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere :- It will measure TEC total electron content.

Lander Craft Module LC

The finalised design for LC consists of pyramid type design with its 3 sides having Solar Panels and the fourth one having a door and a door integrated ladder to deploy the rover, The rover would be piggybacking inside the LC. The lander has four legs to stand and during the launch while LC and OC be united those legs are supposed to be in pulled back position. Their were four main thrusters each providing ~800 N of thrust, later one more was added centrally and 8 other thrusters probably for attitude control while decent, having ~50 N thrust. To navigate the LC precisely it has LIRAP Laser Gyro based Inertial Reference unit and Accelerometer Package. It is an inertial navigation system that would precisely direct the LC to the predetermined landing site.

Reportedly the LC also has cameras around it these cameras can also take pictures to match with pre loaded images to determine weather LC is on the right path. The LC can intelligently self adjust it's trajectory necessary to land on the spot. These cameras are a part of Hazard Detection and Avoidance HDA system. It so happens that after the rough braking phase the Lande will stabilise itself 100 metres above moon’s surface and would slowly decend down during this phase HDA has to ensure it's movement on the right path. The HDA’s cameras would identify correct landing site using scene matching. This system also contains laser altimeters and a laser Doppler velocimiter. The HDA ensures LC would land without any external alien solid object hitting it. As soon as the LC would be 2 metres above the ground it's thrusters would shut down and landing legs streched, the legs are designed to absorb the shock.

Instruments being carried by LC

1 RAMBHA (LP + DFRS) Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere :- It will also measure TEC and also morphology. It will measure near surface plasma density and it's changes with respect to time. According to a recent Nature article, lunar plasma is thought to participate in the levitation of lunar dust, a problem for future human exploration.

2 ChaSTE Chandra’s Surface Thermophysical Experiment :- The job of this one would be the measurement of thermal properties of lunar regolith near polar region.

3 ILSA Instrument for Lunar Seismic Activity :- This is another first of its kind experiment as no one has the data about Lunar Crust at the poles. The ILSA would measure moon's sesmic activity around the landing site. It will be helpful in guessing the structure of Lunar Crust at south pole and mantle.

Rover

I very much wanted the Rover to have some name , it's un-cute to just call it rover.I was happy to kniw it has been named Pragyan. The Rover has 6 wheels that run on independent motors and are attached to the main body via a linkage. Four of the wheels will also be capable of independent steering. A total of 10 electrical motors will be used for traction and steering. The main body is shaped like a matchbox and has two instruments. Their are two cameras one in left and another in right both for navigation purpose. It doesn't have a rear vision but can go in reverse direction. The rover is about 25 kgs. Because of being designed to move on polar surface, the rover has vertical solar panels instead of usual horizontal ones we have seen on other rovers.

The rover will move on moon

Earlier it was planned that their will be two rovers a Russian one and an Indian. The Russian rover was supposed to be based on the Phobos Grunt mission’s rover. This rover was supposed to land on Mars’ moon Phobos but that mission was a failure following which ISRO earlier decided to go on a single rover with Russian assistance and later they decide to go all alone. On August 14, 2013, in reply to a written question in the Rajya Sabha the GOI confirmed that ISRO had decided to undertake the Chandrayaan mission all by itself.

IIT Kanpur was involved in development of certain components like stereophonic camera-based 3D vision, kinematic traction control, and motor dynamics of the rover's six wheels. Dr. K.S. Venkatesh, Associate Professor of Electrical engineering has developed the 3D view component. The 3D vision would create a 3D contour map of Lunar Surface after landing and would use it for navigation and mobility. Based on the obstacles and seams on surface an optimal path will be chosen to reach to a point at the expense of minimum energy. The rover also has to ensure that it's vertical solar panels would always face towards Sun for maximum power generation. The traction control would ensure that rover overcomes the roughness of moon's surface and provides optimum torque to the wheels to move at optimum speeds.

Development of the components was completed in 2012 and the rover is currently under tests.

To simulate the Moon's gravity which is 1/6th of that of earth, a helium balloon has been attached to the test rover which counterbalances 5/6th of the Earth's gravitational force. This can be seen in the pictures around.
The Rover's mobility is being tested a the ISRO Satellite Integration and Testing Establishment (ISITE) in Bangalore. Anorthosite rock from Sithampoondi and Kunnamalai, about 260-km from Bangalore, has been pulverized and laid out at ISITE. It has been spread over to make a mock lunar surface. The chemical and mechanical properties of the pulverized Anorthosite closely resemble those of lunar soil. S. Anbazhagan, Professor and Head of the Department of Geology, Periyar University, told The Hindu, “We had done spectral studies on the lunar soil and we discovered its equivalent at Sithampoondi." Geologists from Periyar University, Salem; the National Institute of Technology, Tiruchi; the, Indian Institute of Science, Bangalore, and the National Geophysical Research Institute, Hyderabad are collaborating with ISRO on the Chandrayaan-2 project.

It is built to communicate with Indian Deep Space Network (IDSN) using the Lander Rover Communication System on-board the Lander, or through the Orbiter Rover Communication System on-board the Orbiter.

The Rover have two scientific payloads. Intended to study moon's surface. Both are designed to do onsite elemental analysis of lunar surface and find out what's the would made of. The LIBS can find lower mass elements and APXS is for higher mass elements.

1 LIBS Laser-Induced Breakdown Spectroscope :- It will determine the chemical and mineralogical composition of Lunar Soil. It is developed by Laboratory for Electro Optic Systems, Bangalore and would do spectral analysis of lunar soil.

2 APXS Alpha Particle X-Ray Spectrometer :- It is developed by Physical Research Laboratory, Ahmedabad. It would determine elemental composition of lunar soil.

Geo-Political Impact

It may pain in the heart of the Chinese that they lost the opportunity to send Asia's fist Mars mission as ISRO did it, But they still own the records of many firsts in the field of Space Exploration. Indians are highly egoistic about their achievements and grossly pessimistic about those things where they got initial failures. We can see Indian media and people bragging about the success of ISRO. They brag that Pakistani Space Agency SUPARCO is older but still less successful than ISRO also take a snub against China which is very wrong activity. It is true that these chievements accompany National Pride with themselves and we all must be proud but taking a jibe on someone who failed trying makes us a loser in long term. During the cold war their was a rivalry amongst USA and USSR to achieve firsts in Space Exploration.

Such a rivalry kills the very basic thing about study of science, that is curiosity. It is curiosity, scientific temper that stimulates people to take bold steps. It doesn't matter who launched the spacecraft first and who second, everyone wins when more and more spacecrafts are launched for exploration purposes. But it isn't necessary that everyone in the world would carry the same feeling of brotherhood that we may seek. India had always been unlike China open to international collaboration and participation of all space agencies in building and managing scientific payloads on it's exploration missions. All the space exploring nations have shared scientific data they recieved. So it's not like we are trying to defeat each other by winning so called Space Race, we all won over our curiosity and the thrust is more now.

ISRO has taken correct and careful steps towards lunar exploration , this step of Chandrayaan 2 would validate many technologies intended for further planetary touch downs. The next Chandrayaan mission after this shall be a sample return type where samples collected by a rover would be ferried back to Earth. Indian prime minister Narendra Modi and his Japanese counterpart Shinzo Abe signed an agreement to collaborate on a future joint lunar sample return mission.

Wish Successful Launch to Chandrayaan 2 !

Images and Info Sources :-

http://www.planetary.org/blogs/emily-lakdawalla/2017/1129-indias-chandrayaan-2-mission.html

https://sites.google.com/site/indianspaceprojects/moon-exploration/chandrayaan---2