India's Sace Odyssey

The God said ‘Let there be Light’ and there was ‘Light’. Straight through the optical 5ft giant lenses I could see the light coming from a 1500 light years distant star. This was the breaking research news for the scientific community at Kalam Space Research Center and Observatory (KSRCO), orbiting at an attitude of 300 nautical miles, inclined 35 degrees to the equator (low-Earth orbit). Scientists at Indian Space Research Organization (ISRO) were all excited.

It has been 80 years when India has first set up a low earth-orbiting observatory, ASTROSAT in 2017. In subsequent missions Kalam Observatory was set up in 2050 taking over a SETI (Search for Extra-Terrestrial Intelligence) project in collaboration with NASA (National Aeronautics and Space Administration). With new discoveries it has now taken a distinct edge over its American counterparts in SETI research. The two telescopes mounted at the Kalam Observatory; APJ-1 and APJ-2 are showing interesting results. A distant solar system with a star and a planet as similar to our Sun and Earth has raised hopes of millions of discovering some creatures living like us. Everyday scientists analyzing the data obtained from Indian observatory are coming up with exciting predictions, some have already discovered water in large quantity and some of them were optimist of finding living creatures. This cousin planet is recently given the name ‘Vikram’ to honor the visionary leadership of Dr Vikram Sarabhai in developing Indian Space Research program.

I remember it was Dr G. Madhavan Nair back in early 21^st century who initiated the project of setting up a low earth orbiting observatory. With the successful fulfillment of India’s first mission to moon Chandrayan-1 in 2009, the country became also interested in setting up a far side moon observatory. To observe most of the astronomical events it is desirable to have data from all wavelengths. Unfortunately earth’s atmosphere absorbs most of the falling radiations. So a need for setting up a low earth-orbiting observatory was felt by astronomers in late 20^th century. Hubble telescope was the first flagship mission of NASA set up in 1990 and was subsequently abandoned in 2013 after many intermittent repairs. Till then a satellite platform has always remain a cumbersome experience because of its very short operational lifetime and lack of continuous technical support. India took a lead in this project setting up the first ever moon observatory ‘Madhavan’ in 2030. For radio astronomy far side of the moon has proved to be the cleanest place in the solar system, from where scientists can observe and collect data without any interference from earth which is blocked away by moon.

‘Madhavan’ is the only observatory in space which has lived more number of years than others without any major repairs. It is expected to work for another 100 years. With the subsequent development in technology it is renowned to be of its excellence in space observations. It is a multi wavelength lunar based observatory that can detect all the wavelengths. For example it can study frequency range lower than 30 MHz which is in the radio range and is impossible to detect from earth surface or near earth orbiting observatory.

This lunar observatory has a much longer life time due to the absence of any oxidant medium like in higher earth atmosphere viz. oxygen. Moon also offers a very low seismic activity. Its seismic quietness can only be disturbed by big hits with meteorites. This helps in taking observations for longer periods without any perturbations.

Madhavan has a unique support system for its maintenance and communication. It has two modules one at the far side of the moon close to the South Pole-Aitken basin and one at the near side of the moon. The lunar far side unit offers complete radio silence for Madhavan and the near side unit helps in establishing good communication of both the units with ISRO at earth. Due to the availability of the unlimited land for laying out systems and instruments at moon’s surface, both these units are equipped with replacement parts and adequate power supply. The maintenance units can assemble smaller structures to larger and bigger ones in the low lunar gravity atmosphere which is relative hard and expensive to do at earth or in low earth orbit. The lunar gravity also helps in proper disposal of the contaminants and debris which keeps moving around in case of low earth orbiting observatory. ISRO in collaboration with NASA has also stationed a staff of 20 scientists and engineers at “Sarv Gyan Moon Research Lab (SGMRL)” on moon’s surface for the support and maintenance of all lunar observatories. So in case of emergency there is no need to send a separate mission in space for troubleshooting. Even the near side unit also offers a very good site of radio astronomy as most of the earth’s emissions get diluted by a factor of 1/r² at such a distance, which are very effective in near earth atmosphere.

Light scattering in earth’s atmosphere produce a diffuse background which makes most of the pictures and data not clearly readable. Absence of atmosphere at Moon’s surface avoids any such effects. One of the largest radio telescopes of the size 400 meters has been recently built to collect more accurate data. However since the set up of Madhavan, lunar observatories have been facing a major problem. The dust rose by different activities such as transportation on and off from the moon’s surface has been a major obstruction in observation due to very high residence time of dust particles in lunar atmosphere. A special system to avoid this problem has been designed. It consists of charged plate which attracts all the ionized dust particles. Moon also has a large variation in temperature during cyclic day and night. For this purpose all the observatory equipments are specially designed by ISRO to resist the effects of thermal expansions and contractions. Most fragile equipments are kept thermally insulated. Very fragile equipments like giant telescope lenses are manufactured at the site by using the support from SGMRL to avoid any risk of shipping from earth.

Both of these India’s flagship observatories ‘Kalam’ and ‘Madhavan’ work in coordination with ISRO. Many unique and interesting astronomical observations like super nova explosions and gamma ray burst have been studied using these two observatories. Kalam once helped in saving the earth from a probable hit of an asteroid falling into the earth orbit from the group of Amors. It detected the asteroid before the ten days of probable collision and the asteroid was then destroyed by firing a nuclear armed missile back in 2080.

At a circular orbit of around 500 km, oxygen atoms are broken by ultra violet rays into very reactive free radicals that degrade fast the exposed surfaces of satellites. Due to this effect India has to destroy its first successful space observatory ASTROSAT after 20 years of its launch. Defense Research and Development Organization (DRDO) then decided to develop smart materials which do not react in oxidant atmosphere. These materials were successfully applied in Kalam Observatory at all the exposed surfaces and even after 57 years it is doing its job properly. At Kalam Observatory measurements of very high accuracy can be achieved. Resolutions in the optical range of wavelengths are far better than the giant telescope observatories set up at the high mountain peaks of Himalayas. Sometimes theoretical diffraction limitations of resolutions can also be achieved.

Low earth orbiting observatories are not effective in keeping track of longer durations of the source object because of its faster orbiting speed. Therefore when the Kalam observatory first detected the light from the Vikram’s solar system, some of the tracking schedules were then transferred to Madhavan observatory which can keep an eye for relatively longer durations. The slow Moon’s rotation speed permits up to a maximum of 14 days continuous exposure. In the earlier space observatories like Hubble and Compton it was observed that pointing accuracy of the satellite relies heavily on a gyroscope and once they fail the satellite become unusable for astronomy. This problem was then controlled by mounting a ‘pseudo gyro’ a software-only gyroscope on the satellites to take over from the failed gyros which has prevented some major backlash in Kalam Observatory. ISRO has also developed efficient solar systems that continuously supply energy to a space satellite.

The classic terrestrial astronomical observations from the earth’s surface have become a history today. No one does research using a monster telescope mounted on the top of a mountain. The satellites provide an excellent platform for astronomical observations in the absence of the disturbance from atmosphere. It has also helped astronomers in coming over the age old limitations of resolution and absorption of certain wavelengths. Lunar observatories are the next step in this aspiration of seeing beyond the limits. While both these types of observatories are self sufficient in providing a clearer picture of universe it appears that lunar observatories have a certain advantage in terms of the higher exposure periods. However before making any decision we should not ignore the role of Kalam Observatory in detecting the distant solar system that has given new directions in SETI research. We should also realize the importance of India’s first multi wavelength astronomy satellite ASTROSAT that has opened the doors of more advanced lunar as well as space observatories for the universe.