Tuesday, August 23, 2011

India's second mission to the moon, Chandrayaan-2, a Rs 425 crore project, took a definite shape with ISRO on Monday announcing details of payloads or scientific instruments to be flown on the orbiter and the rover. Chandrayaan-2 will be launched in 2013 from Sriharikota. Hovering 100km above the moon, Chandrayaan-1 had confirmed water ice last year. Chandrayaan-2, equipped with an array of payloads, will probe closer and deeper for several things on the lunar surface...

What is Chandrayaan-2

The Indian Space Research Organisation (ISRO) is planning 2nd moon mission Chandrayaan-2 in 2013. Russia's Federal Space Agency (Roskosmos) is joining with ISRO for development of Chandrayaan-2 Lander/Rover.

Chandrayaan-2 will consist of the spacecraft and a landing platform with the moon rover.

The rover would move on wheels on the lunar surface, pick up samples of soil or rocks, do a chemical analysis and send the data to the spacecraft orbiting above.

Chandrayaan-2 spacecraft weighs about 2,650 kg at lift-off of which the orbiter weight is about 1,400 kg and lander weight is about 1,250 kg. Development of the subsystems of the orbiter and the rover is in progress at ISRO centres in Bangalore, Thiruvananthapuram and Ahmadabad.

The project is lead by Dr Mayilsamy Annadurai.

Chandrayaan-2 planned to be launched by 2013 using spacecraft and launch vehicle of ISRO. The mission is expected to have an operational life of about 2 years.

Chandrayaan-2 When

The Indian Space Research Organisation (ISRO) and Russia's Federal Space Agency (Roskosmos) have signed an Agreement on joint lunar research and exploration. This cooperation envisages Chandrayaan-2, a joint lunar mission involving a lunar orbiting spacecraft and a Lander/Rover on the Moon's surface. ISRO will have the prime responsibility for the Orbiter and Roskosmos will be responsible for the Lander/Rover. A few scientific instruments from other space agencies may also be accommodated on these systems.Chandrayaan-2 will be launched on India's Geosynchronous Satellite Launch Vehicle (GSLV) around 2013 time frame. This agreement is a major milestone in the long-standing cooperation between India and Russia in the area of outer space.

Chandrayaan-2 How

Chandrayaan-2 will consist of the spacecraft and a landing platform with the moon rover. The platform with the rover will detach itself off after the spacecraft reaches its orbit above the moon, and land on lunar.

A motorized rover will be released on the moon's surface from the lander. The location for the lander will be identified using data from Chandrayaan-1 payload MIP .

In Chandrayaan-1, MIP will itself from the spacecraft and it will impact on the moon's surface. The MIP will have three instruments. Annadurai, its mass spectrometer will sense the moon's atmospheric constituents as it keeps falling for 18 minutes and crashes on the moon. Its altimeter will measure the instantaneous altitude during its descent. Its video-imaging system will look at the moon from close proximity in order that ISRO scientists may take decisions on the terrain where it will land.

The rover will weigh between 30 kg and 100 kg, depending on whether it is to do a semi-hard landing or soft landing. The rover will have an operating life-span of a month. It will run predominantly on solar power.

If ISRO wants to operate the rover for two or three months, its engineers will configure the vehicle and its instruments including a battery back-up to go into a low-power mode, with the rover waking up when sunlight streams through. When the sunlight comes, the solar-powered battery cells will be re-charged and the equipment will be switched on one by one for the rover to function for another two weeks. The batteries will be re-charged every two weeks.

Landing Site

Two candidate landing sites near the Lunar south pole have reportedly been identified by the Russians, based on data from NASA's Lunar Reconnaissance Orbiter (LRO) and Japanese Selena orbiter, which entered lunar orbit in 2007.

The Russian developed Lunar Exploration Neutron Detector, LEND, installed on LRO was used to identify sunlit areas, potentially with sub surface ice. Imagery from Selena and data from LOLA laser altimeter on NASA’s LRO orbiter was used to profile the terrain in these areas.

To begin with 14 sites in sunlight areas close to the South Pole that possibly have subsurface ice were identified...

Nine of these sites were rejected at the outset by the lander team because the terrain was too rough for the landing system of the spacecraft.

The two sites have been short listed. The sites could change if the accuracy of the landing system is improved or based on other data.

Main: 87.2 deg S, 68 deg E, Shoemaker, Faustini

Backup: 88.5 deg S, 297 deg E, Gerlach

Chandrayaan 2 Moon Lander

The Chandrayaan 2 will comprise a 1,200 kg Russian designed and developed moon lander carrying a single 15 kg rover developed by ISRO in collaboration with Russia. The 1,200 kg Russian lander will carry a scientific payload of 35 kg, not including the rover. It will be powered by solar panels

Other than equipment to analyse the lunar soil and detect the presence of water, the lander will carry a seismometer and a laser reflector. Also being considered is a landing beacon that could facilitate future landings.

Russia plans to test the lander in 2011, Roscosmos Deputy Head Anatoly Shilov told AW&ST on August 31, 2010

Chandrayaan 2 Moon Rover

The rover has been designed in Russia but is being fabricated to Russians specs by Indian scientists.

IT Kanpur is developing three subsystems to provide mobility to the Indian rover to be placed on the moon by the Chandrayaan-2 lander.

  • Stereophonic camera based 3D vision: The stereo vision cameras will provide the ground team controlling the rovers a 3D view of the surrounding terrain.
  • Kinematic traction control : Kinematic traction control will enable the rover to negotiate the rough lunar terrain using independent steering provided on four of its wheels.
  • Control and motor dynamics of the rover's six wheels: The rover will have six wheels each driven by an independent electrical motor. Four of the wheels will also be capable of independent steering. A total of 10 electrical motors will be used for traction and steering.

IIT Kanpur started working on the project in March 2009 and is scheduled to complete it by 2010 when the rover traction system will be handed over to ISRO for final testing and evaluation.

A significant part of the rover, including its communication package, is being fabricated in Kerala.

'We're launching Chandrayaan 2 for a total coverage of the moon'

India's first lunar mission Chandrayaan-1 had accomplished nearly 95 per cent of its scientific objectives and is considered a success internationally. Why is India returning to the moon?

There are still a lot of outstanding issues about the moon, which have to be resolved in greater depth. Some of the experiments of Chandrayaan-1, moreover, achieved only 50 per cent to 70 per cent of their objectives. Again, due to power limitations, the Terrain Mapping Camera of Chandrayaan-1 could map only 45 per cent of the moon. We are launching Chandrayaan-2 because we need a total coverage of the moon, employ improved and new technology and obtain better quality photo imageries. The orbiter with the five payloads will be flying at an altitude of 200 km above the lunar surface and we estimate that its lifespan would be for two years depending on the use of the propellant.

A significant aspect of Chandrayaan-2 is that the orbiter, unlike in Chandrayaan-1, does not have any foreign payloads even though NASA and the European Space Agency showed interest. Is there any reason why foreign payloads have been removed?

As per the present plan we do not have any weight in the orbiter for foreign payloads. We were keen on giving an opportunity to our scientists. This is why we decided not to invite international participation this time. Keeping this in view we, unlike in Chandrayaan-1, did not issue a formal Announcement of Opportunity calling for international participation. Even at the last moment if we decide to have foreign payloads on Chandrayaan-2 after making weight allowances, we have to issue an Announcement of Opportunity, an elaborate exercise, which can delay the flight. The total mass of the five payloads on the orbiter is about 40 kg at the moment and we are trying to reduce it, which may be difficult.


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