Science & Nature Club at the Periyar Nagar Public library had its montly meet on September 4, 2016 at the library premises. Dr. Duraiswamy Navaneetham PhD spoke about the past and future of ‘Space Exploration’.

The Periyar Nagar Public library is located at the intersection of Karthikeyan Salai and Kandasamy Salai at Periyar Nagar, Chennai 82. All are welcome to the talks and registration is free. For more details contact 9962565743 or check https://sites.google.com/site/coovamlizards/explore.

Excerpts from the talk on ‘Space Exploration’

Science is driven by curiosity. Curiosity about the world around them leads humans to explore. Exploration leads to discovery. The story of space exploration is interesting as well as awe-inspiring. Space exploration expands the horizons of human knowledge as it uncovers near and far celestial objects in space and helps understand the significance or rather the insignificance of Earth in the grand scheme of things. It also has spin-offs in terms of news discoveries and inventions originally intended for spacecraft or astronaut use, later making their way into everyday life, for instance, the use of prosthesis, cordless tools, microwave ovens and medical scans.

The beginnings. For many centuries peoples around the world have been observing the sky and surmising what they saw. While stories about creation and visible celestial objects in the sky like planets, stars and constellations abound in mythologies in various cultures, there were some serious thinkers too, who tried to rationalize what they saw over their heads. These people came up with theories to explain observed celestial movements and occurrences which they also backed up with mathematical proofs. So it happened with the ancient Greeks, Indians, Chinese and other astronomers from around the world. In India Aryabhata, Bhaskaracharya and the likes made significant contribution to observational astronomy. In the early part of the last millennium, European figures like Copernicus, Kepler, Brahe and Galileo laid the foundation of modern astronomy. But people were still observing space from their own backyard i.e., the earth.

The Space Age dawned when unmanned and manned missions into space left the earth behind. It all started with the Soviets sending their first satellite Sputnik I into space in October 1957. During that period of cold war (between the USA and the USSR), the Americans not wanting to be left behind, joined the space race when they sent out their own Explorer series of satellites. These early satellites were just primitive (compared to today’s advance) objects that registered a beep for every complete revolution or orbit around the Earth.

First humans in space. The Soviets sent cosmonaut Yuri Gagarin, the first human to orbit the earth in a spacecraft in 1961. The US caught up by sending Alan Shephard into space and later John Glenn into orbit around the Earth. In 1963 Valentina Tereshkova of the USSR was the first woman in space and also the first human to spend 3 days in space making 48 orbits of the Earth.

Landing on the moon. Not to be outdone by the Soviets, in 1961 American president John F. Kennedy vowed to put his men on the moon before the end of the decade. And the National Aeronautics and Space Administration (NASA) of USA made it possible. US had several Gemini missions to train space-faring astronauts for moon landing. On the Apollo mission 11 in 1969, while mission commander Michael Collins stayed in the control module orbiting the moon, fellow astronauts Neil Armstrong and Buzz Aldrin landed on the moon in their lunar module or ‘Eagle’ lander. After walking around the surface of the moon for a while, they were able to successfully blast off from there and later dock with Collins’ control module in orbit. The trio successfully returned back to Earth on the control module that safely landed in the Pacific Ocean.

(While the Americans in the pre-shuttle days mastered returning astronauts’ water landing in the oceans, the Soviets landed their cosmonauts in the deserts of Kazakhstan. Also warranting mention is the fact that even during the period of cold war, the USSR and the USA worked together in the larger interest of science and successfully carried out the spacecrafts Apollo-Soyuz docking in 1975).

Planetary and Interplanetary Missions. Robotic Spacecraft or probes are sent into space to explore moon, planets, asteroids, comets and even the Sun. These could be of different types: fly-by, orbiter, lander, rover and return-mission. Early probes to Venus and Mercury such as the USSR’s Venera and US’ Mariner missions (1967) were of the fly-by type where the probes flew past their targets while capturing their images. Pioneer and Voyager missions (1977) to the outer planets namely Jupiter, Saturn, Uranus and Neptune are also of this kind. The Viking mission to Mars (1976) went a step further where the spacecraft orbited the target planet and later landed there. Such landers, besides sending close-up pictures also analyze soil/rock samples thus greatly adding to our understanding of these planets. India’s Mars Orbiter Mission (MOM) or Mangalyaan of 2013 is of the orbiter type. The Casssini-Huygens mission that was launched in 1997 from the US is an orbiter-lander type spacecraft to Saturn and its moon Titan, where the Huygen probe landed on the moon Titan. The Mars Pathfinder mission sent out in 1997 pioneered the rover-type of probes by first landing, Sojourner, its automated rover that could move across the Martian surface thus covering more territory. In 2010 Japanese Aerospace Exploration Agency’s return-mission probe Hayabusa brought back dust samples from the asteroid 25143 Itakawa.

Early Space Stations. These are space laboratories orbiting the Earth and manned by crews of astronauts who stay here for extended periods of time conducting experiments. USSR’s Salyut 1-7 group (1971-1986) and USA’s SkyLab (1973-1979) were the early space stations or research labs in space. These stations served a variety of purposes – as a launch pad for rockets, to study effects of zero gravity on living organisms including humans and to conduct other experiments in space. This was followed by a more permanent settlement in space – the USSR’s and later Russia’s ‘Mir’ from 1986 to 2001.

Soyuz Spacecraft is Soviet designed human space-flight vehicle. The first Soyuz manned flight of 1967 ended in a crash killing its sole cosmonaut. But all the later flights (with the exception of 1977 Soyuz 11’s disaster killing all three crew members) have been successful. Soyuz is considered the longest operational, safest and most cost-effective manned spacecraft to date.

Space Shuttle. This is a system used by NASA for its human space-flight missions. The ‘orbiter’ module (shuttle components include reusable orbiter vehicle, recoverable solid rocket boosters and expendable external tank containing cryogenic liquid fuel) that carries the astronauts is reusable. Columbia, Challenger, Discovery, Atlantis and Endeavour are the reusable orbiters of the Space Shuttle Orbiter fleet. Challenger was lost to a launch disaster in 1986 killing all seven crew aboard while Columbia burnt up during re-entry into Earth’s atmosphere in 2003 when all seven crew members including Indian-origin Kalpana Chawla lost their lives. The Space Shuttle program has been discontinued by the US government since 2011.

International Space Station (ISS) is a joint venture of several countries, prominent among them being the USA and Russia. The first modules were the American Unity and Russian Zarya in 1999. The first astronaut expedition arrived in 2000 and the space station has been occupied continuously by international crew ever since. ISS can be seen in the night sky, lighted up not by artificial lights (unlike aircrafts), but by the reflection of Sun’s light on its surface. Its movement is usually in north-east or south-east direction. Since the discontinuation of American Space Shuttle program in 2011, crews are brought aboard the ISS by the Russian Soyuz spacecraft. There is always one Soyuz spacecraft docked at ISS to be used by the crew for escape in case of an emergency.

Hubble Space Telescope (HST). A space telescope that floats about 600km above the Earth in space, is operated remotely from the Goddard Space Flight Center in Maryland, USA. Being outside of the earth’s atmosphere would provide distortion-free images and further this optical telescope can penetrate deeper into space to capture clearer pictures of far-away galaxies and other celestial objects. HST’s revolution time on its orbit around the Earth is 90 minutes. It was launched in 1990 by space shuttle Discovery. Its observations are in the near-ultraviolet, visible and near-infrared spectra region.

Chandra X-ray telescope is another space observatory in space but with a 64-hour orbit around the Earth. It was launched by space shuttle Columbia in 1999. Unlike optical telescopes, this examines the X-rays emitted from objects in space. Scientists use it to study the sources of such X-rays i.e., black holes and exploding stars.

Future Missions. In the year 2011, the US government announced that the future of space technology will be in private hands. Keeping with that a lot of private players are in the picture now. Notable among them are US’s Space X who specialize in taking cargo to ISS, US’ Orbital Sciences who are involved in satellite launches and the British Virgin Galactic that promotes space tourism. There is a probability that India might follow the same path and ISRO director Dr. Kiran Kumar had lately spoken of a need for private players in Indian Space Program.

Image: Dhurai A.N.