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.
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.
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.
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 :-
Chandrayaan-1 was India’s first unmanned lunar probe. It was launched by the Indian Space Research Organization (ISRO) in 22nd October 2008, and operated until August 2009. Chandrayaan-1 is aimed at chemical, mineralogical and photo-geologic mapping of the moon in visible, near infrared, low energy and high energy X-rays with high spatial resolution.
Specifically, the objectives will be to carry out high-resolution three-dimensional mapping of topographic features along with the simultaneous mapping of distribution of minerals such as Si, Al, Mg, Ca, Ilmenites (FeTiO3, which may retain 3He) and elemental chemical species including radioactive nuclides. This mapping could unravel the mysteries about the origin and evolution of the planetary system in general and moon-earth system in particular.
Looming at about 384,400 km from the Earth, the Moon is the brightest object in the night sky and only second in brightness to that of the Sun. It has a diameter of 3,476 km and a mass of 7.35x1022 kg with a mean density of only 3.35 g/cc as compared to 5.52 g/cc of that of Earth. It has no atmosphere and degassing from the surface produces only trace gases. The gravitational force on the Moon is only 1/6th of that of Earth, and is not able to retain its atmosphere. The Moon does not have a substantial core of molten iron like Earth and hence has no magnetic field. The Moon undergoes extremes in temperature. It is scorching heat at 110º C during the day and freezing cold at .180º C during night.
The Moon.s surface is generally dry, dusty and rocky. The rocky crust is about 60 km thick on the near side that faces the Earth and about 107 km on the far side. Moon.s terrain is divided into two sharply contrasting areas. The rugged and very ancient mountainous .Highlands regions and smooth younger lowland, Maria regions. While Earth.s mountain ranges are formed by movements and coming closer of crust sections pushing against each other (known as plate tectonics), the lunar highlands did not result from an active uplifting process due to crustal dynamics. But its surface has been periodically bombarded with different sizes of meteorites and asteroids. During the initial period of lunar evolution, such giant meteor impacts resulted in the creation of flatlands or lunar basins. The regions not affected by these giant impacts are the lunar highlands.
Ancient observers thought that the round and dark areas on the face of the Moon are seas, which they called Maria (Latin word for seas). Maria are not seas at all but relatively flat areas produced by massive flow of lava from earlier period of lunar volcanism. Maria comprises 16 percent of the Moon.s surface and has huge impact basins. They are concentrated in the near side of the Moon. Associated with the Lunar Maria are gravity anomalies called mascons (mass concentrations). A spacecraft would accelerate as it nears the Maria region and decelerate as it moves away due to such gravitational anomalies.
The Moon is covered with a gently rolling layer of powdery soil and rock fragments called the regolith, which is made of debris created by the meteor impacts forming the craters. Such craters are the remains of collisions between an asteroid, comet or meteorite and the Moon. The size, mass, speed and angle of the falling object determine the size, shape and complexity of resulting craters. Surface of the Moon is scarred with millions of impact craters and the record has been retained on Moon,s surface.
One striking difference between the lunar surface material and that of Earth concerns the most common kinds of rocks. On the Earth the most common rocks are sedimentary because of atmospheric and water erosion of the surface. On the Moon there is no atmosphere and little or no water, and the most common kind of rock is igneous (.fire-formed-rocks.). According to studies, the lunar surface material has the following geological characteristics:
Analysis of lunar rock samples indicate that
The abundance of radioactive elements in rock samples can be used to determine the age of the rocks in a process called radioactive dating. Using such techniques on lunar samples brought back by the Apollo missions, it has been found that the oldest material from the surface of the Moon is almost as old as we believe the Solar system to be that is 5 billion years. Thus the material brought back from the Moon by Apollo missions provides a window on the very early history of our Solar system that would be difficult to find on the Earth, which is geologically active and has consequently obliterated its early geological features.
Seismic S waves apparently do not traverse the region below the zone of Moonquakes, suggesting that this material has very low shear strength, possibly containing some liquid.
Origin of Moon
The origin of the Moon is still not clearly understood and there have been speculations about its origin how it was formed and how it acquired its present orbit around the Earth. Studies using the chemical, mineralogical, isotopic and chronological data led to postulation of five major theories on the origin of the Moon:
The Fission Theory:
At some time in the distant past, the Moon had separated from the Earth Perhaps the Earth was not as round then as it is today and that imbalance caused it to split in two.
The Capture Theory:
The Moon was formed somewhere in the solar system and was later captured by the gravitational field of the Earth.
The Co-accretion Theory:
The Earth and Moon may have been formed at the same time from solar nebula by co-accretion.
The Colliding Planetesimal Theory:
Moon condensed from the debris of the interaction of Earth-orbiting and Sun-orbiting planetesimals (very large chunks of rocks like asteroids) early in the history of the solar system.
The Giant Impact Theory:
A planetesimal of Mars size had impact with the Earth, early in its history, ejecting large volume of matter from the evolving Earth, which aggregated and formed the Moon.
Apart from the scientific interest, the Moon could have economic benefits to mankind. This includes exploitation of the resource potential of the Moon including habitation of the Moon to reap the benefits on a continuous basis. The Moon has abundant resources of oxygen, hydrogen and other solar wind gases trapped in its regolith. Understanding the availability of such resources from the perspective of mineralogy, lithology and regional geology is a prerequisite for efficient human presence on the Moon. Early studies of the lunar regolith showed that there is a relative abundance of Helium-3 (3He) isotope on the Moon compared to that of Earth. 3He can be used as a fusion element and is thus considered as one of the important fuels for power generation in the future. Since 3He has high diffusivity, it normally gets lost from lunar grains. However, the mineral Ilmenite (FeTiO3) is abundant on the Moon and has high retentivity for 3He. The distribution of 3He associated with Fe and Ti can be determined by geochemical mapping since it would have the same distribution as (Fe + Ti). Over the four billion-year history of the Moon, several hundred million tonnes of 3He have impacted the surface of the Moon from the solar wind. The analyses of Apollo and Luna samples showed that over 1 million tonnes of 3He still remain embedded in the surface of the Moon. Even a small fraction of this could provide the world.s electricity for centuries to come. A large number of studies are being carried out to determine the technical feasibility of having a human outpost on the Moon.
The twenty-first century will mark a significant milestone in the history of human development: the colonization of the Moon! The Moon being the nearest neighbor of Earth and with 1/6 th of the Earth’s gravity offers a unique outpost for planetary exploration. The conditions may be adapted to generate lunar self-sustaining bases for such endeavors. Moon’s far side would provide an excellent site for establishing an astronomical observatory because of the absence of atmosphere and the absence of Earth’s reflected radiation on the far side of Moon.
Propulsion in a broad sense is the act of changing the motion of a body. Propulsion mechanisms provide a force that moves bodies that are initially at rest, changes a velocity, or overcomes retarding forces when a body is propelled through a medium. Jet propulsion is a means of locomotion whereby a reaction force is imparted to a device by the momentum of ejected matter.
Rocket propulsion is a class of jet propulsion that produces thrust by ejecting stored matter, called the propellant. Duct propulsion is a class of jet propulsion and includes turbojets and ramjets; these engines are also commonly called air-breathing engines. Duct propulsion devices utilize mostly the surrounding medium as the "working fluid", together with some stored fuel.
The energy source most useful to rocket propulsion is chemical combustion. Energy can also be supplied by solar radiation and, in the past, also by nuclear reaction. Accordingly, the various propulsion devices can be divided into
Radiation energy can originate from sources other than the sun, and theoretically can cover the transmission of energy by microwave and laser beams, electromagnetic waves, and electrons, protons, and other particle beams from a transmitter to a flying receiver. Nuclear energy is associated with the transformations of atomic particles within the nucleus of atoms and can be of several types, namely, fission, fusion, and decay of radioactive species. Other energy sources, both internal (in the vehicle) and external, can be considered. The energy form found in the output of a rocket is largely the kinetic energy of the ejected matter; thus the rocket converts the input from the energy source into this form. The ejected mass can be in a solid, liquid, or gaseous state. Often a combination of two or more of these is ejected. At very high temperatures it can also be a plasma, which is an electrically activated gas.
DUCT JET PROPULSION
This class, also called air-breathing engines, comprises devices which have a duct to confine the flow of air. They use oxygen from the air to burn fuel stored in the flight vehicle. The class includes turbojets, turbofans, ramjets, and pulsejets.
Rocket propulsion systems can be classified according to the type of energy source
The basic function
The type of vehicle
Another way is to Classify by the method of producing thrust.
A thermodynamic Expansion of a gas is used in the majority of practical rocket propulsion concepts. The internal energy of the gas is converted into the kinetic energy of the exhaust flow and the thrust is produced by the gas pressure on the surfaces exposed to the gas,
This same thermo-dynamic theory and the same generic equipment (nozzle) is used for jet propulsion, rocket propulsion, nuclear propulsion, laser propulsion, solar-thermal propulsion, and some types of electrical propulsion. Totally different methods of producing thrust are used in other types of electric propulsion or by using a pendulum in a gravity gradient.
Chemical Rocket Propulsion
The energy from a high-pressure combustion reaction of propellant chemicals, usually a fuel and an oxidizing chemical, permits the heating of reaction product gases to very high temperatures (2500 to 4100°C or 4500 to 7400°F). These gases subsequently are expanded in a nozzle and accelerated to high velocities (1800 to 4300 m/sec or 5900 to 14,100 ft/sec). Since these gas temperatures are about twice the melting point of steel, it is necessary to cool or insulate all the surfaces that are exposed to the hot gases. According to the physical state of the propellant, there are several different classes of chemical rocket propulsion devices. Liquid propellant rocket engines use liquid propellants that are fed under pressure from tanks into a thrust chamber.
A typical pressure-fed liquid propellant Rocket engine system is schematically shown in Fig
The liquid bipropellant consists of a liquid oxidizer (e.g., liquid oxygen) and a liquid fuel (e.g., kerosene). A monopropellant is a single liquid that contains both oxidizing and fuel species; it decomposes into hot gas when properly catalyzed.
A large turbopump-fed liquid propellant rocket engine is shown in this Fig
Gas pressure feed systems are used mostly on low thrust, low total energy propulsion systems, such as those used for attitude control of flying vehicles, often with more than one thrust chamber per engine. Pump-fed liquid rocket systems are used typically in applications with larger amounts of propellants and higher thrusts, such as in space launch vehicles.
In the thrust chamber the propellants react to form hot gases, which in turn are accelerated and ejected at a high velocity through a supersonic nozzle, thereby imparting momentum to the vehicle. A nozzle has a converging section, a constriction or throat, and a conical or bell-shaped diverging section Gas pressure feed systems are used mostly on low thrust, low total energy propulsion systems, such as those used for attitude control of flying vehicles, often with more than one thrust chamber per engine. Pump-fed liquid rocket systems are used typically in applications with larger amounts of propellants and higher thrusts, such as in space launch vehicles.
Some liquid rocket engines permit repetitive operation and can be started and shut off at will. If the thrust chamber is provided with adequate cooling capacity, it is possible to run liquid rockets for periods exceeding 1 hour, dependent only on the propellant supply. A liquid rocket propulsion system requires several precision valves and a complex feed mechanism which includes propellant pumps, turbines, or a propellant-pressurizing device, and a relatively intricate combustion or thrust chamber.
In solid propellant rocket motors the propellant to be burned is contained within the combustion chamber or case. The solid propellant charge is called the grain and it contains all the chemical elements for complete burning. Once ignited, it usually burns smoothly at a predetermined rate on all the exposed internal surfaces of the grain. Initial burning takes place at the internal surfaces of the cylinder perforation and the four slots. The internal cavity grows as propellant is burned and consumed. The resulting hot gas flows through the supersonic nozzle to impart thrust. Once ignited, the motor combustion proceeds in an orderly manner until essentially all the propellant has been consumed. There are no feed systems or valves
Gaseous propellant rocket engines use a stored high-pressure gas, such as air, nitrogen, or helium, as their working fluid or propellant. The stored gas requires relatively heavy tanks. These cold gas engines have been used on many early space vehicles as attitude control systems and some are still used today. Heating the gas by electrical energy or by combustion of certain monopropellants improves the performance and this has often been called warm gas propellant rocket propulsion.
Hybrid propellant rocket propulsion systems use both a liquid and a solid propellant. For example, if a liquid oxidizing agent is injected into a combustion chamber filled with solid carbonaceous fuel grain, the chemical reaction produces hot combustion gases.
There are also chemical rocket propulsion combination systems that have both solid and liquid propellants. One example is a pressurized liquid propellant system that uses a solid propellant to generate hot gases for tank pressurization; flexible diaphragms are necessary to separate the hot gas and the reactive liquid propellant in the tank.