BENGALURU: The word ‘space exploration’ brings to mind images of science fiction movies like Star Trek, Star Wars, The Martian, Interstellar, or Guardians of the Galaxy. Humankind has already begun throwing hints of such explorations and adventures becoming a reality, although we are still in the very early stages.
How soon that can be achieved depends on many challenges – space transportation, propulsion technology, the speed of space travel, deep space environment and how potentially hazardous it could be for humans, communication systems, and sustenance (food, water, breathable air during space travel and at destinations). The challenges have thrown up a question on high costs and the potential – but very real – dangers involved while “going out there”. This was addressed by the former administrator of the USA’s National Aeronautics & Space Administration (NASA), Michael Griffin, in a speech at the Bay Area Houston Economic Partnership.
He segregated “why space exploration” into “acceptable reasons” and “real reasons”, the former dealing with economic benefits, national/international security and related issues, and the latter with curiosity, competitiveness and the actual benefits in terms of enhancing human life based on such explorations. He said, “Who among us does not know the wonder and mystery and awe and magic of seeing something, even on television, never seen before, an experience brought back to us by a robotic space mission? When we do things for real reasons, as opposed to acceptable reasons, we produce our highest achievements.”
Just imagine how vast and limitless the universe is, and how small and insignificant we are in comparison, living on what eminent astronomer, Carl Sagan, famously described as the “Pale Blue Dot”, the Earth, our home.
The Solar System, where Earth belongs, is part of the Milky Way Galaxy. It is estimated that there are 100 billion stars in this galaxy alone. There are estimated to be two trillion galaxies in the universe. This puts an estimate on the number of stars in the universe at a mind–blowing figure of 200 billion trillion – that is ‘2’ followed by 23 zeroes!
We still have no clue about our closest neighbouring stellar system, Alpha Centauri, which is 4.24 light-years away. It is our extreme insignificance in this humongous massive expanse of the limitless universe that drives us to space exploration – to know what lies out there. Besides, United Nations Environment Programme (UNEP) cited scientists pointing out that Earth has already reached a carrying capacity population of 8 billion, thereby making colonisation of other planets a necessity in order for our descendants to survive.
Moon's lure
So far, 148 lunar missions have been run by various countries led by the USA and the erstwhile Union of the Soviet Socialist Republic (USSR) mostly in competition with each other than in cooperation. It started with seven consecutive failures in 1958, the year attempts at reaching the Moon began. The USSR scored the first successful fly-by of the Moon with Luna-1 on January 2, 1959, although its plan to impact the lunar surface failed.
Later that year, the USSR scored the first-ever man-made impact on the lunar surface with Luna-2 on September 14, 1959. Just a decade later, humans set foot on the Moon. Spurred on by the historic message of President John F Kennedy on May 25, 1961, to a joint session of Congress, committing to land an American on the Moon and return him safely back to Earth, astronaut Neil Armstrong became the first human to set foot on the Moon on July 20, 1969.
At precisely 10.56 pm Eastern Day Time (8.26 am on July 21, 1969 in India) Armstrong radioed back to Earth: “Houston, Tranquility Base here, the Eagle has landed.” Six hours later, Armstrong stepped off the Moon lander Eagle’s ladder onto the lunar surface at the Sea of Tranquility site, and said what echoes even today: “That’s one small step for man, one giant leap for mankind!”
So far, only 12 men have gone there and returned between 1969 and 1972 on six successful Apollo missions conducted by NASA. These missions were from Apollo-11 to 17. Apollo-13 failed to land and returned to Earth after orbiting the Moon due to an onboard oxygen tank explosion. Since 1972, high costs prohibited humans from going beyond the Earth's orbit, let alone reaching the Moon. But now, NASA, with international collaboration, is planning to send humans back to the Moon in 2024-25 under the Artemis programme, for which India too has signed a protocol in June.
In this intervening period of 51 years, space scientists and agencies, including the Indian Space Research Organisation (ISRO), have used space probes and orbiting spacecraft to discover valuable resources on the lunar surface – including water ice and water molecules near the lunar south pole that ISRO’s Chandrayaan-1 helped find.
The Chandrayaan-1 mission – a Moon-orbiting mission launched in October 2008, and active until August 2009 – carried NASA’s Moon Mineralogy Mapper (M3) spectrometer, which detected water ice near the lunar poles. Chandrayaan-1 released the Moon Impact Probe (MIP), which intentionally crashed on the lunar surface to raise a dust plume. This allowed M3 to detect water molecules in the plume – a first-time discovery of water on the Moon.
Now, humans aim to set up bases on the Moon to exploit various resources to be returned to Earth. The aim is to exploit Moon-based hydrogen, oxygen, silicon, iron, magnesium, calcium, aluminium, manganese and titanium, among which oxygen, iron and silicon are more in abundance.
India’s Chandrayaan-3 and Russia’s Luna-25 (see graphics) are already in the Moon orbit to make their landings on August 23 and between August 21 and 23, respectively. As part of the lunar and space-bound efforts, NASA along with the US Department of Energy’s National Nuclear Security Administration (NNSA) has been developing the Kilopower nuclear fission system since October 2015. It is an experimental project entailing new nuclear reactors for powering space transportation vehicles and future human bases on the Moon and Mars.
The appeal of Mars, Venus and Mercury
Mars, Venus and Mercury – the ‘inner planets’ of the solar system – are Earth’s closest neighbours and, therefore, attract maximum attention. Mars and Venus have hogged the attraction, but not so much Mercury. Since October 10, 1960 to July 30, 2020, 49 unmanned missions have been sent carried out to Mars, the special appeal being the red planet’s similarities with Earth.
Scientists are increasingly confident that Mars could host humans on its surface at bases made conducive for human life. According to European Space Agency data, Mars’ atmosphere is 95.32% carbon dioxide, 2.7% nitrogen, 1.6% argon and 0.13% oxygen; and the atmospheric pressure at the surface is more than over 100 times less than that of Earth’s -- not conducive for human life without life-support mechanisms.
NASA’s data indicates Mars’ surface temperatures vary between 20 degrees Celsius and -153 degrees Celsius as the lack of adequate atmosphere allows heat to escape. There is also speculation on whether life did exist on Mars or even continues to exist under the surface, which is much similar to that of Earth, but without greenery. Mars-3 of the USSR on December 2, 1971 was the first to make a soft landing on Mars, and the first partial image was transmitted showing grey background with no details. But contact was lost 20 seconds after transmission started, and data from its rover too could not be obtained.
However, the first successful Mars lander, deployed from NASA’s Viking-1 orbiter, landed on the Martian surface on July 20, 1976, and operated for 2,245 sols (Martian days).
Mars Pathfinder, Sojourner, Phoenix, InSight and Perseverance were successful Mars landers and rovers, while Ingenuity, a helicopter, successfully carried out the first aerodynamic flight on another planet on April 19, 2021 after landing with Perseverance rover on February 18, 2021, and being deployed on April 3, 2021. It was the USSR which made the first attempt at a mission to Venus on February 4, 1961, trying to impact the Venusian surface, but failed just like the next three attempts by the USSR and the USA.
Venera-1 of the USSR, on May 19, 1961, was the first to record a Venus fly-by and the first to do so with another planet, although it failed to achieve its intended objective of impacting the Venusian surface.
A total of 46 missions have been sent to Venus, of which 28 were successful, which included the USSR’s partial success at landing with Venera-7 on December 15, 1970. But after the landing, the spacecraft rolled over, severely limiting the data relayed back to Earth. But it recorded the first soft landing on another planet.
The first successful landing was made by Venera-8 of the USSR on July 22, 1972, and Venera-9 successfully carried out an orbiting-and-landing mission on October 20, 1975, followed by Venera-10 just five days later on October 25. NASA data indicates that Venus has a thick, toxic atmosphere filled with carbon dioxide and it’s perpetually shrouded in thick, yellowish clouds of sulphuric acid that trap heat, causing a runaway greenhouse effect.
It is the hottest planet in the Solar System, although Mercury is closer to the Sun. The Venusian surface temperatures are about 475 degrees Celsius, enough to melt lead, and the surface is rusty-coloured, peppered with intensely crunched mountains and thousands of large volcanoes. Most missions to Venus have been fly-bys or atmospheric missions.
Mercury is the most difficult to explore among the inner planets. The challenge lies in its proximity to the Sun, and being the fastest orbiting planet in the solar system, which makes it difficult to manoeuvre a spacecraft into an orbit around it. Despite that, NASA’s Mariner-10 and MESSENGER missions could make close observations of Mercury. According to NASA, Mercury has no atmosphere; instead, it has a thin exosphere consisting of atoms blasted off the surface by the solar wind and striking meteoroids. That exosphere is composed mostly of oxygen, sodium, hydrogen, helium and potassium.
Outer planets, neighbouring stellar systems
Relatively lesser is known about the outer planets, referred to as gas giants — Jupiter, Saturn, Uranus and Neptune. Pluto, which is known as the ninth planet, has now been adjudged as a “dwarf planet”. Even lesser — or close to nothing — do we know about our closest neighbouring stellar system: Alpha Centauri. Just nine missions have visited the outer planets of the Solar System.
Pioneer-10 flew by Jupiter and its moons in 1973; Pioneer-11 followed in 1974 besides flying by Saturn and its moons; Voyager-1 did the same in 1979 and 1980; Voyager-2, achieved that and added fly-bys of Uranus in 1986 and Neptune in 1989; Ulysses did a gravity assist with Jupiter in 1992 and 2004; Galileo was the first Jupiter atmospheric mission in 1995 before settling into an orbit around it (1995-2003); Cassini-Huygens made a gravity assist of Jupiter in 2000 and settled into an orbiting mission around Saturn in 2004 before landing on Saturn’s moon Titan; New Horizons made a gravity assist of Jupiter in 2007; and Juno is orbiting Jupiter.
Two fly-by missions to asteroids sharing Jupiter’s orbital pathway and Jupiter are being planned. One is NASA’s Lucy, a space probe launched in October 2021 for a 12-year journey to eight different asteroids, visiting two main belt asteroids as well as six asteroids sharing Jupiter’s orbit around the Sun; and Jupiter Icy Moons Explorer, launched by European Space Agency on April 14, 2023, to orbit around Jupiter and its moon Ganymede in 2031.
Of these, Pioneer-10, Pioneer-11, Voyager 2, Voyager 1 and New Horizons have exited the Solar System and are headed into deep space, hoping to be intercepted by some intelligent extraterrestrial civilisation.
Chandrayaan-3 and Luna-25....
Lander Vikram's payloads
RAMBHA-LP (Langmuir Probe) To measure the near-surface plasma (ions, electrons) density and its changes with time
ChaSTE (Chandra’s Surface Thermo-physical Experiment) to carry out the measurements of thermal properties of the lunar surface near the polar region
ILSA (Instrument for Lunar Seismic Activity) to measure seismicity around the landing site and delineate the structure of the lunar crust and mantle
Rover Pragyaan's payloads
APXS (Alpha Particle X-Ray Spectrometer) to derive the chemical composition and infer mineralogical composition to further enhance our understanding of the lunar surface
LIBS (Laser Induced Breakdown Spectroscope) to determine the elemental composition (Mg, Al, Si, K, Ca,Ti, Fe) of lunar soil and rocks around the lunar landing site
Propulsion module payload
SHAPE (Spectro-polarimetry of HAbitable Planet Earth), and experimental payload to study the spectro-polarimetric signatures of the habitable planet Earth in the near-infrared (NIR) wavelength range (1-1.7 μm)
‘Ultimate aim to find alternative location for human settlement'
G Madhavan Nair Former Chairman, Indian Space Research Organisation
Space is the next frontier for human exploration, and India has demonstrated its capability by developing self-reliant capabilities to access outer space and build platforms for scientific observations, resource surveys and communication.
It was Dr Vikram Sarabhai’s grand vision six decades ago which nucleated space research in India. Just after USSR launched the first artificial satellite, Sputnik, he saw the potential of using space technology for human development. He insisted on India developing high technology and utilising it for enriching the quality of life of the common man.
His vision was the driving force behind the Indian space programme. Indian Space Research Organisation (ISRO) has lived up truly to his expectations. ISRO had systematically undertaken the development of complex technologies for space research and emerged as a superpower in the space arena. From small beginnings, launching a sounding rocket for atmospheric studies in 1963, ISRO has come a long way reaching its arm up to the Moon.
Right from the early stages, ISRO targeted the development of application programmes to survey natural resources based on earth observation satellites. Such programmes have become part of our day-to-day life. They are benefiting farmers, fishermen, forest and water resource management. Earth observation data is contributing to predicting extreme weather events and helping in disaster management. Communication connectivity has revolutionised telephony, TV broadcasting and data transmission to every nook and corner of India.
The indigenous navigation system is providing accurate timing and localisation data for critical applications. The satellite-based remote observation and communication systems are contributing to our defence services as well.
While meeting the needs of people, resources are being utilised to get in-depth knowledge about the universe and our planetary system. As part of this, we sent spacecraft to the Moon and Mars. The ultimate aim is to have a detailed exploration of our neighbours with the intention of looking for exotic minerals, and ultimately an alternate location for human settlement.
ISRO has plans to develop capabilities to carry humans to outer space and return safely. India has a prominent place among space-faring nations and continues its efforts in developing this technology to maintain its leadership position.
Space technology encompasses almost all branches of engineering, and mastery of it is proof of our advancement in technology. Several spin-off benefits contribute to high-reliability products for the common man. Challenges associated with astronomy and space exploration in developing the cutting edge of technology is a highly motivating factors for the youth in India.