Chandrayaan-1 heads closer to its destination!

India’s mission towards moon took a step ahead when the fourth orbit-raising manoeuvre of Chandrayaan-1 was carried out successfully on Wednesday, October 29. The space craft was successfully raised to its fourth orbit in the morning around 7.30. This achievement has been revealed in a statement released by the Indian Space Research Organisation (ISRO) in Bangalore. ISRO stated that during the course of the operation at the spacecraft’s 440 Newton liquid engine was fired for about three minutes.

Mr. M. Annadurai-the Project Director of Chandrayaan-1 said that everything went on according to the plan. With this, the lunar spacecraft has moved closer to the moon. Now, the Chandrayaan-1 has made its entry into a more elliptical orbit whose apogee (farthest point to earth) lies at 2,67,000 km while the perigee (nearest point to earth) lies at 465 km. Thus, it implies the fact that the spacecraft’s present orbit extends more than half the way to the moon.

How Chandrayaan-1 is Raised to Higher Orbits

Chandrayaan-1 could have been fired to reach the moon, which is about 3,84,000 km from earth, in one shot. But that was not done. Instead the spacecraft is being moved towards the moon in increasingly elliptical orbits with an apogee (farthest point from the earth) increasing many times more than the perigee.

“We could have done it one shot, but there is a possibility of missing the moon,” said M. Annadurai, Project Director of Chandrayaan-1 to this Correspondent. “So we have adopted an incremental increase in the orbits’ perigee.”

That probably explains why the Indian Space Research Organisation (ISRO) has decided to settle for five increasingly elliptical orbits before Chandrayaan-1 reaches the moon’s sphere of influence. Why is the firing always undertaken at the perigee position?

Firing at perigee

“To increase the apogee, we must fire at the perigee [position]. And firing should consume less energy. So the firing is done at the perigee,” Dr. Annadurai explained.

One more reason to fire at the perigee is to ensure that the spacecraft can be tracked by 3-4 ground stations. “The spacecraft is allowed to complete one or more orbits till such time 3-4 ground stations can track it. But we will fire it at the earliest opportunity,” he said.

But not always can one assume that the firing will happen as planned. So any change in this will in turn affect the apsidal line (imaginary line that connects the apogee and perigee). This should be corrected and maintained if the rendezvous with the moon is to happen.

Increasing the apogee

And what ensures that the apogee increases many hundred kilometres after every firing while the perigee changes by only a few kilometres? “When the firing is done exactly at perigee, the velocity increases and the apogee keeps increasing. There will be no change in the perigee position,” he said.

But firing the spacecraft exactly at the perigee position is only theoretically possible. This results in a small change in the perigee altitude.

Duration of firing

“It is not an instant firing [at the perigee]. It takes a few hundred seconds to complete the firing,” he said. But great effort is however taken to centre the firing around the perigee position.

For instance, the first firing to take Chandrayaan-1 from the initial orbit to the first orbit (with an apogee of 38,000 km) took about 1060 seconds to complete. The second firing to take the spacecraft to the nearly 75,000 km apogee took 920 seconds. And the third firing to raise it to about 1,65,000 km apogee took 560 seconds.

The fourth firing to take Chandrayaan-1 to 2,67,000 km will take about 190 seconds and finally the last raise to 3,80,000 will take 150 seconds.

Though the original plan was to reach 2,00,000 km apogee in the third orbit, ISRO could only raise it to 1,65,000 km. So will that lead to any problems? “This can be made up for in the next firing,” Dr. Annadurai said.

Use of propellant

Will the change in the orbit-transfer strategy from five-and-half days to nearly a fortnight lead to increased fuel consumption and hence reduced mission life? “The amount of propellant required to fire the spacecraft to 4,00,000 km is less, whether it is done in one shot or in stages. And the propellant is used only for changing the orbits and not for orbiting around the earth,” he explained.

Orbiting around the earth is mainly through the gravitational force of the earth. But the gravitational influence of sun and moon would still play a role, though minor. Since the spacecraft goes around only for a few days in each orbit, there will not be any change in the orbits and hence the need to use propellant to correct the orbits would not arise.

But that will not be case when Chandrayaan-1 orbits the moon for two years. “There will be a need to correct the orbit once in two weeks to maintain a 100 km circular orbit,” said Dr. Annadurai.

Less energy required

While earth’s gravitational force will exist even when the spacecraft moves further and further away from the earth, the force will decrease with distance. “So firing it to the fourth and fifth orbit will require less energy,” said Dr. Annadurai. “Since some propellant is already used in the previous firings, the overall mass would come down. So the effort required to fire reduces.”

Reverse firing

Five-and-half days after the fifth firing, Chandrayaan-1 will have its rendezvous with the moon. Chandrayaan-1 will get nearer to the moon on November 8 when it reaches the 3,81,000 km apogee.

Though the moon’s influence will be predominant, the velocity of Chandrayaan-1 has to be reduced to enable the moon to capture it. Else, it can fly past the moon.

Once captured by the moon’s gravity, the velocity of the spacecraft has to be reduced to help it reach its final destination of 100 km circular orbit around the moon.

This is achieved by reversing what was done to raise its orbits.

“First, the firing is resorted at both perigee and apogee positions. And the firing takes place only after the orientation of the spacecraft is reversed — turned 180 degrees,” he said.

While the momentum of the spacecraft allows it to move in the same direction, the reverse firing helps it to reduce the velocity. The reduction in velocity is again undertaken in an incremental manner to reach the predetermined 100 km circular orbit around the moon.

Chandrayaan a wake-up call for America

WASHINGTON: From the White House to the Presidential campaign trail to the American scientific community, India’s modest Chandrayaan moon
venture, while greeted warmly, reminded the US that it was getting sloppy in maintaining its supreme lead in space expedition. ( Watch )

Democratic candidate Barack Obama, whose alert campaign staff seem to keep him abreast of any development in India (he was quick to condole the death of Field Marshal Maneckshaw even before the White House took notice), used India’s moon launch to tell Americans that they were taking their eyes off the ball.

“With India’s launch of its first unmanned lunar spacecraft following closely on the heels of China’s first spacewalk, we are reminded just how urgently the United States must revitalise its space programme if we are to remain the undisputed leader in space, science, and technology,’’ Obama said, promising to revitalise the US space programme and close the gap between the Space Shuttle’s retirement and its next-generation replacement including funding $2 billion more for Nasa.

“But more money alone is not enough,’’ he warned. “We must not only retain our space workforce so that we don’t let other countries surpass our technical capabilities; we must train new scientists and engineers for the next generation.’’ The winding down of the Space Shuttle programme and budgetary battles have constrained the US space program although President Bush stepped up to give it a boost last year.

The White House, too, pro forma hailed India’s moon mission as “encouraging’’ and “exciting.’’ But away from presidential politics and polemics, the US scientific and business community greeted the event with gusto, seeing it as an opportunity for collaboration for a greater good.

Nasa, which has two instruments on board, said data from its two instruments will contribute to its increased understanding of the lunar environment as it implements the nation’s space exploration policy, which calls for renewed robotic and human missions to the moon.

“The opportunity to fly Nasa instruments on Chandrayaan-1 undoubtedly will lead to important scientific discoveries,’’ Nasa Administrator Michael Griffin said. “This exciting collaboration represents an important next step in what we hope to be a long and mutually beneficial relationship with India in future civil space exploration.’’

Much of India’s early space ventures were undertaken with Nasa help and collaboration before the two countries fell out in the 1990s during a phase of technology denials and embargo, some of which still continues to this day.

Meanwhile, the United States India Business Council (USIBC), representing 280 of the largest US companies investing in India, also hailed the mission as the beginning of long “relationship promoting the opening of the frontier of outer space.’’

“This unique technology partnership in civil space exploration, which taps India’s highly skilled scientific expertise with American instrumentation furnished by Raytheon, beckons what we hope will be a long and mutually beneficial relationship promoting the opening of the frontier of outer space,’’ USIBC president Ron Somers said.

The Chandrayaan venture even made it to the widely watched evening network news (each of which has ten times the viewership of cable channels such as CNN and Fox) as an example of India’s progress and intent.

Space Network Guides Chandrayaan's Orbit Around Earth

The precise orbiting of India's first lunar spacecraft Chandrayaan-1 around the earth is being monitored by the telemetry, tracking and command network (Istrac) of the Indian Space Research Organisation (ISRO), a top official said in Bangalore on Friday.

"Very precise orbit determination of Chandrayaan is in progress for planning its next manoeuvre over the next two days. Health parameters of the lunar spacecraft are also being evaluated," ISRO director S. Satish told IANS.

With no orbit-raising planned on Friday, the 1380 kg spacecraft is spinning around the earth elliptically at an apogee (farthest from earth) of 37,902 km and a perigee (closest to earth) of 305 km.

"In this orbit, the spacecraft goes around the earth once in 11 hours and 5 minutes. Its health is perfectly all right and is able to send/receive signals at regular intervals from our network and ground stations," Satish said.

ISRO's deep space network (DSN) at Bylalu, about 40 km from this tech hub, is also involved in the manoeuvring exercise. It tracked the spacecraft and received signals in s and x band and sent commands in turn.

"The actual role of DSN will come into play when the spacecraft crosses 100,000 km (apogee) from the earth when its signals become feeble and time-consuming," the official said.

Chandrayaan launched Oct 22 at 6.22 am onboard the 316-tonne polar satellite launch vehicle (PSLV-C11) from the Satish Dhawan Space Centre at Sriharikota spaceport, about 80 km north of Chennai.

The spacecraft is expected to enter the lunar orbit Nov 3 when the moon will be about 500 km away (perigee).

A series of complex manoeuvres in the final phase will put Chandrayaan in the final orbit November 8, which will be about 100 km from the moon's surface.

Chandrayaan carries 11 scientific instruments, including six foreign payloads — two from the US, three from the European Space Agency (ESA) and one from Bulgaria. The remaining five are indigenously designed and developed by the various centres of the state-run ISRO.

Inside Chandrayaan-1

Inside Chandrayaan-1

Bangalore: Chandrayaan-1 spacecraft, carrying 11 scientific instruments, weighs about 1400 kg at the time of its launch and is shaped like a cuboid with a solar panel projecting from one of its sides.

The state-of-the-art subsystems of the spacecraft, some of them miniaturised, facilitate the safe and efficient functioning of its 11 scientific instruments, according to Indian Space Research Organisation.

The spacecraft structure has been built mainly using composites and aluminium honeycomb material. The thermal subsystem consisting of paints, tapes, multi layer insulation blanket, optical solar reflectors, heat pipes, heaters and temperature controllers, ensures the proper functioning of the spacecraft by keeping its temperature within acceptable limits.

The mechanisms subsystem of Chandrayaan-1 spacecraft takes care of the deployment of its solar panel and the steering of the dual gimballed antenna.

The spacecraft is powered by a single solar panel generating a maximum of 700 W.A 36 Ampere-Hour (AH) Lithium ion battery supplies power when the solar panel is not illuminated by the sun.

The Telemetry, Tracking and Command subsystem of Chandrayaan-1 working in S-band takes care of radioing the detailed spacecraft health information, facilitating the knowledge about spacecraft`s position in space and allows the reception and execution of commands coming from earth by the spacecraft.

Sun and star sensors as well as gyroscopes provide the orientation reference for spacecraft in space.

To make Chandrayaan-1 spacecraft escape from orbiting Earth and travel towards the moon, its liquid apogee motor (LAM) is used. Liquid propellants needed for LAM as well as thrusters are stored onboard the spacecraft.

Chandrayaan-1 spacecraft`s Communications subsystem transmits the precious information gathered by its eleven scientific instruments to Earth in `X-band` through its Dual Gimballed Antenna.

Chandrayaan-1 spacecraft was built at ISRO Satellite Centre, Bangalore with contributions from ISRO/Department of Space (DOS) establishments like Vikram Sarabhai Space Centre (VSSC), Liquid Propulsion Systems Centre (LPSC) and ISRO inertial Systems Unit (IISU) of Thiruvananthapuram, Space Applications Centre (SAC) and Physical Research Laboratory (PRL) of Ahmedabad and Laboratory for Electro-optic Systems (LEOS) of Bangalore.

‘October 22 good day for moon mission launch’

Chandrayaan-1 has no Insurance Cover

Bangalore, Oct 11, 2008: India’s first moon voyage is set to be launched October 22. But Chandrayaan-1 has got no insurance cover. This may be amazing to most people but this is the reality. This may be due to the confidence of Indian scientists who know that this will be a sure success and due to this reason they don’t want to spend a single penny on getting insurance cover for the historic and momentous Chandrayaan-1.

By the way it is like general practice. Indians, generally middle class Indians are not known to be attracted to insurance. They want to avoid the cost of getting insurance cover. May be it is due to the fact that they simply don’t have the means to get insurance covers for them and their kids.

It is not the case that Chandrayaan has not cost the country and ISRO anything. The nation has spent around Indian rupees 3860 million on the project during the last five years. In my view it is the general national attitude towards insurance that ISRO has not gone for an insurance cover for an important product.

The ISRO officials have said that the project in not covered under any insurance as Chandrayaan-1 is a scientific project and that it would not require any insurance cover. “We have not taken any cover for this project,” S Satish, spokesperson of ISRO said.

The Made-in-India rocket bearing the lunar spacecraft will lift off as per schedule provided the weather is right. As per the plan, the 1.5-ton Chandrayaan spacecraft will take approximately eight days to travel about 240,000 miles before reaching its final orbit 60 miles above the surface of the moon. A crash landing of a lunar vehicle on the moon's surface is also planned.

India’s First Unmanned Lunar Mission Chandrayaan-I All Set To Be Launched

The nation is all set to see the launch of India’s first unmanned lunar mission Chandrayaan-I. The spacecraft which has now been shifted to Sriharikota, has completed all environmental tests and would go for launch on board PSLV-C11, by the end of this month.

The tests related to environment required the spacecraft to undergo vibration and acoustic tests. These tests were successfully completed at the ISRO Satellite Centre at Bangalore. The sources have revealed that the launch vehicle has been tested till the fourth stage

Chandrayaan-I another Step Closer to Moon

Chandrayaan I, India’s spacecraft which is to take off for the moon, is on its way to SHAR, ie, Sriharikota Range, to be integrated with PSLV-C11. The 50-hour countdown to the launch of Chandrayaan will start on the night of October 19.

At Sriharikota, Chandrayaan will be put through its paces on the ground. Indian Satellite Research Organisation (Isro) scientists will check how its solar panels will deploy. It will also undergo electrical and mechanical tests. Chandrayaan had earlier undergone preliminary thermal and vibration tests at Isro Satellite Centre (ISAC) in Bangalore.

For security threats arising from Naxalites and other possible extremist attacks, the exact location of Chandrayaan is being kept under wraps even as it is being provided tightest possible security, according to sources in Isro. Chandrayaan is expected to reach SHAR in a day or two.

The upgraded version of PSLV, PSLV-C11, which has a lift-off weight of 316 tonnes, will be used to inject the 1,304-kg mass spacecraft into a 240 x 24,000 km orbit.

The main objective of Chandrayaan-I is investigation of the distribution of various minerals and chemical elements and high-resolution three-dimensional mapping of the entire lunar surface. ISRO’s Polar Satellite Launch Vehicle (PSLV) will launch Chandrayaan-I into a 240 km x 24,000 km earth orbit. Subsequently, the spacecraft’s own propulsion system will be used to place it in a 100-km polar orbit around the moon.

M Annadurai, project chief, Chandrayaan, had said earlier: “This will be the first step towards our manned mission to the moon.”

The remote sensing satellite will weigh 1,304 kg (590 kg initial orbit mass and 504 kg dry mass) and carry high-resolution remote sensing equipment for visible, near infrared, soft and hard X-ray frequencies. Over its expected lifetime of two years, it will survey the lunar surface and produce a map of its chemical characteristics and three-dimensional topography.

The project, expected to cost Rs 386 crore, will study the surface of the moon using light. Many other countries are also looking at the possibility of mining the abundant mineral resources on the moon.