Sections

Introduction

Types of Orbits

India’s Satellite Applications

India’s Satellite Launch Vehicles

Extra-Terrestrial Exploration

Future Projects

References

[The following is the script of a talk which was given virtually on 25 May 2021 at the United Services Institution of India to the its faculty, and undergraduate and postgraduate students taking part in a summer internship programme at the Institution. It is presented in two parts: This first part covers spacecraft, launchers and exploration aspects while Part II gives an insight into organisations, the NewSpace phenomenon and the militarisation of space including capabilities of global space powers. Each part is of approximately 30 mins duration.]

Introduction

At the outset, I would like to thank the Director USI for inviting me to give a talk on “India’s Space Program”, a subject which is gaining increasing importance with every passing year from a national economic as well as security perspective. India has made commendable progress in the space sector over the last few decades, and my talk aims to give an overview of India’s profile and achievements in this sector.

This being an internship program for bright young minds about to launch themselves in their respective careers, I must comment here that space continues to capture the imagination of our younger generation, since it presents an inexhaustible potential for exploration, discovery and diverse uses that modern society demands. Space technology can be leveraged for enhancing human welfare, disaster management and conflict prevention, as also quench mankind’s thirst for exploration and offer a means of survival for the human race as earth becomes less habitable.

Importantly, the national security implications of space can no longer be ignored. Space has already been designated as a warfighting domain, together with the traditional domains of land, sea, and air, with cyber being the newest addition to the list [1]. The major world powers are moving ahead vigorously towards developing military space and counter-space capabilities. With China, a daunting adversary, sitting next door, India cannot afford to drag its feet while trying to keep pace with these significant developments, which have grave implications for our national security.

Another key facet which needs to be taken note of is the recent commercialisation of the space sector. The term NewSpace refers to initiatives being taken in this direction. While earlier, the state used to have a monopoly over the sector, private actors now play an increasingly important role, a notable example being SpaceX in the United States. The world today is seeing the emergence of NewSpace as a revolution in space industry, with private industries leading the way in applying the expertise acquired by space agencies as commercial value propositions. Currently, India contributes to barely 2% of the approximately $350 billion-dollar global space economy [2]. Policy formulation for space commerce, especially with regard to the private sector’s role in this all-important sector is extremely relevant for the growth of India’s space endeavours.

In this introductory talk, I shall first briefly acquaint you with the various types of satellite orbits and the most common space applications, and then outline India’s achievements in these application areas. A brief look will then be taken at India’s launch vehicles, exploration missions and future plans. I shall then introduce you to organisations which have so far steered India’s space endeavours, including some new establishments which will spur these endeavours to newer heights. I shall devote a significant slice of my time in discussing the national security implications of this important warfighting domain. Finally, we shall have a look at the important aspect of commercialisation of the space sector.

Types of Orbits

So let us begin by understanding the main features of the most commonly used orbits. These are Geostationary Orbit (GEO), Low Earth Orbit (LEO), Medium Earth Orbit (MEO), and the Polar Orbit with the Sun-synchronous Orbit (SSO) as a special case [3, 4].

Geostationary Orbit (GEO)

Satellites in GEO circle Earth above the equator from west to east following Earth’s rotation, taking 23 hours 56 minutes and 4 seconds (a sidereal day [5]), travelling at exactly the same rate as Earth. This makes satellites in GEO appear to be ‘stationary’ to a ground observer. The speed of GEO satellite is about 3 kms per second at an altitude of 35,786 km.

GEO is used by telecommunication satellites, so that an antenna on Earth can be fixed to always stay pointed towards that satellite without moving. Satellites in GEO cover a large range of Earth so as few as three equally spaced satellites can provide near global communication coverage. Satellites in GEO are also used by weather monitoring satellites to observe weather trends over specific areas.

Low Earth Orbit (LEO)

Satellites in Low Earth Orbit (LEO) are at an altitude ranging from 160 to 1000 kms. By comparison, most commercial aeroplanes do not fly at altitudes much greater than approximately 15 kms. Satellites in this orbit travel at a speed of around 8 kms per second, taking approximately 90 minutes to circle Earth. Unlike GEO that must always orbit along Earth’s equator, the planes of LEO can be tilted, giving more available routes, which is one of the reasons why LEOs are commonly used.

LEO’s lower altitude makes it useful for these satellites to achieve a higher image resolution, and also for communications since lesser power is needed. However, LEO satellites used for communications require complex tracking from ground stations, because they move so fast across the sky. In order to provide constant coverage, communications satellites in LEO work as part of a large constellation.

Medium Earth Orbit (MEO)

Satellites in Medium Earth Orbit are usually at altitudes between 10000 kms and 20000 kms, taking two and eight hours to orbit the Earth, and requiring between 8 and 20 units to provide complete coverage of the Earth. As an example, a constellation with 24 MEO satellites could have four covering any given spot on the earth at any time during the day, which caters for communications outages caused by inclement weather, as also achieves greater accuracy in position tracking.

Satellites in MEO are popularly used for navigation purposes, or for communications with lower power requirements, higher throughput, and lower latency. All popular navigation constellations, namely, US’s GPS, Russia’s GLONASS, Europe’s Galileo, and China’s Beidou mostly use MEO. Notably, the Indian Navigation with Indian Constellation (NavIC) system is based on GEO, and not MEO, satellites.

Polar Orbit and Sun-Synchronous Orbit (SSO)

Satellites in polar orbits usually travel past Earth from north to south passing roughly over Earth’s poles, with altitudes ranging between 200 and 1000 kms, similar to LEO. North-south orbits with an inclination of up to 30 degrees are still classified as polar orbits. Polar orbits provide coverage of the full globe because of the Earth’s rotation.

Sun-Synchronous Orbit (SSO) is a particular kind of polar orbit. Being synchronous with the sun means that satellites in these orbits are always in the same ‘fixed’ position relative to the Sun, ie, the satellite always visits the same spot at the same local time, allowing imaging under same lighting and angular conditions over a period of time. This helps to predict weather or storms; monitoring emergencies like forest fires or flooding; or to accumulate data on long-term problems like deforestation or rising sea levels.

India’s Satellite Applications

Space applications can broadly be grouped into the following categories: earth observation, communications, navigation, scientific & exploration, and experimental. I shall explain these in brief in the context of India’s space programme.

Earth Observation (Remote Sensing) Applications: The IRS/ EOS Series

Earth observation satellites are equipped with remote sensing technology and are thus also known as remote sensing satellites. These are used to study vegetative conditions, ground and sea surface temperatures, ground elevation, cloud conditions, water distribution, urban and rural development, disaster management, etc. Various sensors equipped on these satellites are as follows:-

• Optical Sensors. These sensors observe the reflection of sunlight including invisible ultraviolet and infrared rays, and the Earth’s radiation [6].
• Microwave Sensing. Because of their long wavelengths compared to the visible and infrared, microwaves can penetrate through cloud cover, haze, dust, and all but the heaviest rainfall as the longer wavelengths are not susceptible to atmospheric scattering. Microwave sensors can be active or passive [7].
• Active Microwave Sensors. Active microwave sensors transmit microwaves to the target and receive the reflected microwaves. This method is not affected by clouds and does not require sunlight, so it can be used in all weather conditions and also during the night.
• Passive Microwave Sensors. Passive microwave sensing is similar in concept to thermal remote sensing. All objects emit microwave energy, though in small amounts. These are detected by passive microwave sensors.

Starting with IRS-1A in 1988, ISRO has launched many remote sensing satellites, making India’s remote sensing constellation the largest in operation today globally, which provide data in diversified spatial, spectral, and temporal resolutions. Presently, there are 18 remote sensing satellites in operation [8, 9].

All IRS satellites are placed in polar Sun-synchronous orbit (except Geo Imaging Satellites (GISATs), the first of which is scheduled to be launched in Aug 2021). The initial versions were named as IRS 1 (A, B, C, D), while the later versions were divided into sub-classes named based on their function, eg, Oceansat, Cartosat (for cartography
applications), Hyper-Spectral Imaging Satellite (HySIS), Electro-Magnetic Intelligence Satellite (EMISAT) and ResourceSat (for resource management). The nomenclature was changed to “EOS” in 2020.

Communication Applications: The INSAT Series

Satellite communications have become ubiquitous globally for such diverse applications as Television, DTH Broadcasting, Digital Satellite News Gathering (DSNG) and VSAT. The technology has matured substantially over past three decades.

A communications satellite relays and amplifies radio telecommunication signals via a transponder, ie, it creates a communication channel between a source transmitter and a receiver at different locations on Earth. Out of the approximately 3000 satellites in operation today, nearly half are communications satellites. Most communications satellites are in geostationary orbit therefore tracking is a trivial function. As stated earlier, only three satellites in GEO are needed to provide global communication coverage.

ISRO’s Indian National Satellite (INSAT) system is one of the largest domestic communication satellite systems in the Asia-Pacific region with a large number of operational communication satellites placed in GEO. Established in 1983 with commissioning of INSAT-1B, this system initiated a major revolution in India’s communications sector and sustained the same subsequently.

The INSAT system is a joint venture of the DOS, Department of Telecommunications, India Meteorological Department, All India Radio and Doordarshan. The nomenclature of satellite series was shifted to GSAT (Geostationary Satellite) from INSAT in 2001, which was further changed to CMS (Communication Satellite) from 2020 onwards. These satellites have been in use by Indian Armed Forces as well. GSAT-9, also referred to as the SAARC Satellite, is a notable example of providing communication services for India’s smaller neighbours. Presently there are 5 INSAT, 19 GSAT and 1 CMS series satellites in operation [10, 11].

Navigation Applications: GAGAN and IRNSS (NavIC)

ISRO has operationalised two navigation satellite systems, namely, the GAGAN and NavIC systems, which I shall now describe to you [12, 13, 14].

GAGAN Satellite Navigation System. GAGAN (GPS Aided GEO Augmented Navigation) has been jointly developed by ISRO and the Airport Authority of India to provide accurate navigational services over Indian Flight Information Region (FIR). GPS alone does not meet the the navigational requirements of the International Civil Aviation Organization (ICAO) for accuracy, integrity, and availability. GAGAN augments the GPS for providing better position accuracy. It consists of a set of ground reference stations positioned across various locations in India, which gather GPS satellite data. The reference stations help in generating GPS correction messages, which re-broadcasted via three geostationary satellites (GSAT-8, GSAT-10, and GSAT-15). GAGAN was certified for full functionality in 2015.

Navigation with Indian Constellation (NavIC). Indian Regional Navigation Satellite System (IRNSS), with an operational name NavIC, is designed to provide position information service to users in India as well as the region extending up to 1500 km from its borders. NavIC provides two types of services, namely, Standard Positioning Service (SPS) and Restricted Service (RS). The RS is encrypted and provides a higher accuracy (1-5 m). It is a regional satellite navigation system developed by ISRO, which is under total control of Indian government. The requirement of such a navigation system is driven by the fact that access to global navigation systems like GPS is not guaranteed in hostile situations. The constellation consists of seven active satellites. Three of these are located in GEO and four in inclined GSO (IGSO). The system is intended to provide an absolute position accuracy of better than 10 metres throughout Indian landmass and better than 20 metres in the balance area of operation. The GPS, for comparison, had a position accuracy of 20-30 m. In 2020, Qualcomm has launched four new 4G chipsets and one 5G chipset with support for NavIC.

Scientific Satellites

Indian space programme encompasses research in areas like astronomy, astrophysics, planetary and earth sciences, atmospheric sciences, and theoretical physics. Balloons, sounding rockets, space platforms and ground-based facilities support these research efforts.

Experimental Satellites

ISRO has launched many small satellites for experimental purposes. India’s first satellite, Aryabhata, launched by a Soviet rocket in April 1975, was an experimental satellite carrying x-ray, astronomy, and solar physics related payloads. APPLE (Ariane Passenger Payload Experiment) was ISRO’s first indigenous, experimental communication satellite. The INS-1C (ISRO Nano Satellite), launched in Jan 2018, is the most recent experimental satellite, designed to carry out multi-spectral imaging.

India’s Satellite Launch Vehicles

Today India has two operational launchers or launch vehicles: the Polar Satellite Launch Vehicle (PSLV) and the Geosynchronous Satellite Launch Vehicle (GSLV). However, the first launch vehicle which successfully put a satellite into orbit was the Satellite Launch Vehicle (SLV) [15].

The Vikram Sarabhai Space Centre is responsible for the design and development of launch vehicles. Two more ISRO establishments, the Liquid Propulsion Systems Centre and ISRO Propulsion Complex, develop the liquid and cryogenic stages for these launch vehicles. The Satish Dhawan Space Centre is responsible for integration of launchers. It houses two operational launch pads from where all GSLV and PSLV flights take place. An overview of India’s launch vehicles is as follows.

Satellite Launch Vehicle (SLV)

Satellite Launch Vehicle (specifically SLV-3) was the first space rocket to be developed by India. The initial launch in 1979 was a failure followed by a successful launch in 1980 (which carried the 35 kg Rohini-RS1 satellite into orbit) making way for India into the club of countries with orbital launch capabilities. The SLV had a total of four launches, two of which were successes, with the last launch carried out in 1987 [16].

Augmented Satellite Launch Vehicle (ASLV)

ASLV was another small launch vehicle being developed in the 1980s to place satellites into geostationary orbit. However, due to repeated failures and lack of funds, this project was dropped in favour of the PSLV project [17].

Polar Satellite Launch Vehicle (PSLV)

PSLV was the first medium-lift launch vehicle from India which enabled India to launch all its remote-sensing satellites into LEO. It can take up to 1.75-ton payload to Sun-Synchronous Orbits. Its first successful launch was in 1994. Due to its unmatched reliability, PSLV has also been used to launch various satellites into GEO and GSO, eg, satellites from the NavIC constellation. Despite two partial failures, PSLV has become the primary workhorse for ISRO with more than 50 successful launches, placing hundreds of Indian and foreign satellites into orbit. Besides, the vehicle has successfully launched two spacecraft, Chandrayaan-1 in 2008 and Mars Orbiter Spacecraft in 2013 [18].

Geosynchronous Satellite Launch Vehicle (GSLV)

GSLV was envisaged in the 1990s to transfer significant payloads to GEO. ISRO initially faced problems in the development of GSLV as US had blocked India from obtaining cryogenic technology from Russia. This encouraged India to develop its own cryogenic engines. GSLV Mk II, now referred to simply as GSLV, has an indigenously developed cryogenic upper stage (CE-7.5), which can carry 2-ton payloads to GEO and 5-ton payloads to LEO. GSLV’s primary payloads are the INSAT communication satellites. With its first launch in 2001, GSLV has achieved more than ten successful launches so far.

GSLV Mark III

GSLV Mk III is the heaviest in operational service with ISRO. Equipped with a more powerful cryogenic engine (CE-20) than GSLV, GSLV Mk III is designed to carry 4-ton payloads into GEO or 10-ton payloads to LEO, which is about twice the capability of the GSLV Mk II. It has had three successful launches so far (GSAT-19, GSAT-29 and Chandrayaan-2). It is also expected to carry India’s first manned mission to space, now delayed to 2023 [19].

Extra-Terrestrial Exploration

There are three missions for extra-terrestrial exploration which have been undertaken by India so far: Chandrayaan I & II and the Mars Orbiter Mission (MOM).

Chandrayaan-1

Chandrayaan-1 was India’s first mission to the Moon. It included a lunar orbiter, and an impactor called the Moon Impact Probe. ISRO launched the spacecraft using a PSLV on 22 Oct 2008, which entered into lunar orbit about two weeks later. It carried 11 high-resolution remote sensing equipment for visible, near infrared, and X-ray frequencies, five of which were Indian and six more from NASA, the European Space Agency (ESA) and other American and European Institutes. While planned for two years, the mission was operational for a little over ten months. During this period, it surveyed the lunar surface to produce a complete map of its chemical characteristics and 3-dimensional topography, focussing on the polar regions which were expected to have ice deposits. Chandrayaan-1 became the first lunar mission to discover existence of water on the Moon [20].

Chandrayaan-2

Chandrayaan-2, India’s second moon mission, was launched using GSLV Mk-III on 22 Jul 2019, and consisted of a lunar orbiter, the Vikram lander, and the Pragyan lunar rover, all of which were developed in India. It was the first moon mission meant to explore the south pole region. The main objective of the Chandrayaan-2 mission was to demonstrate ISRO’s ability to soft-land on the lunar surface and operate a robotic rover on its surface, in addition to some scientific aims.

The Vikram lander, carrying the Pragyan rover, was scheduled to land on the near side of the Moon. However, the lander deviated from its intended trajectory at the very last moment, starting from an altitude of about 2 km, and telemetry was lost seconds before touchdown. A review board concluded that the crash-landing was caused by a software glitch. The lunar orbiter was efficiently positioned in an optimal lunar orbit, extending its expected service time from one year to seven years. There will be another attempt for soft landing on moon, but without an orbiter. This was earlier scheduled in 2021 but has now been postponed to 2022 due to the COVID pandemic [21].

Mars Exploration: Mangalyaan

The Mars Orbiter Mission (MOM), also known as Mangalyaan, was launched into Earth orbit on 5 Nov 2013 by ISRO using a PSLV. The MOM probe spent about a month in Earth orbit, where it made a series of seven apogee-raising orbital manoeuvres before being injected towards Mars on 30 Nov, ie, 25 days later. After a 298-day transit to Mars, it was put into Mars orbit on 24 Sep 2014. It carried a payload of 15 Kgs comprising five scientific instruments for atmospheric and surface imaging studies [22].

Mangalyaan was India’s first interplanetary mission and it made India the fourth space agency to achieve Mars orbit, after Roscosmos, NASA, and the European Space Agency. India also became the first country to enter Mars orbit on its first attempt, and the mission was completed at a record low cost of Rs 450 crore.

On 24 Sep 2020, MOM completed six years in orbit around Mars, and is still operational.

Future Projects

In the coming years, in addition to a number of communication and earth observation satellites, ISRO plans to send humans into space (Gaganyaan, scheduled in 2023) and later establish a space station to facilitate a few weeks long stay of astronauts. ISRO aims to develop and operationalise more powerful and less pollutive rocket engines, deploy more telescopes in space and develop satellite navigation systems with global coverage. Longer term plans may include manned landings on moon and other planets as well. Let us get an insight into some of the near-term projects.

Launch Vehicles and Engines

Notable development projects undertaken by ISRO include the semi-cryogenic engine, reusable launchers, and small satellite launch vehicles.

Semi-Cryogenic Engine. The engine (SCE-200) will be less pollutive and more powerful than the current cryogenic engine CE-20. When mated with GSLV Mark III, the engine will boost its payload capacity from the existing 4-ton to possibly 6-ton [23].

Methalox Engine. Methane and liquid oxygen-based engines are being developed to ensure reusability of engines. Methane is less pollutive, leaves no residue and hence the engine can be reused.

Reusable Launchers. There are two reusable launcher projects ongoing at ISRO. One is the ADMIRE test vehicle, conceived as a vertical take-off vertical landing (VTVL) system and another is Reusable Launch Vehicle Technology Demonstrator (RLV-TD) [24], similar to the American space shuttle, which will be launched vertically but land like a plane. The latter will also act as a testbed to evaluate various technologies such as hypersonic flight, autonomous landing, and powered cruise flight.

Small Satellite Launch Vehicle. Small Satellite Launch Vehicle (SSLV) is a compact small lift launch vehicle primarily aimed at tapping the small satellites market. This launcher can be quickly assembled with low power and hence facilitates far higher launch frequency. The planned SSLV can place a 500 kg payload into a 500 km LEO. Its maiden flight is expected sometime in 2021 [25].

Extra-Terrestrial Probes

Lunar Exploration. Chandrayaan-3 is India’s planned second attempt to soft land on the moon after the failure of Chandrayaan-2, now postponed to 2022 due to the pandemic. The mission will only include a lander-rover set and will communicate with the orbiter of Chandrayaan-2 [26].

Mars Exploration. Mangalyaan-2 has been proposed for launch in 2024. The newer spacecraft will be significantly heavier and better equipped than its predecessor.

Venus Exploration. ISRO is planning an orbiter mission to Venus called Shukrayaan-1 to study its atmosphere. Scheduled for 2025, it will include a payload of 100 kg comprising instruments from India and other countries including France, Russia and maybe the US.

Solar Probes. India’s first solar mission, named Aditya L1, to study the solar corona, is due for launch in 2022.

With that we have covered the essentials of India’s space program.

 [Continued in Part II – India’s Space Programme: Organisations and Warfighting Potential]

References

(1)      Lt Gen (Dr) R S Panwar, 21st Century Warfare: From Battlefield to Battlespace, Future Wars, 06 Oct 2017, Accessed 16 Jul 2021.

(2)      Preparing to Scale New Heights: Enhancing Private Participation in India’s Commercial Space Sector, PwC, Jan 2020, pp. 15, Accessed 16 Jul 2021.

(3)      Three Classes of Orbits, NASA Earth Observatory, 04 Sep 2009, Accessed 16 Jul 2021.

(4)      Types of Orbits, The European Space Agency, 30 Mar 2020, Accessed 16 Jul 2021.

(5)      Sidereal Time, Wikipedia, Accessed 17 Jul 2021.

(6)      Optical Remote Sensing, Centre for Remote Sensing and Processing, National University of Singapore, Accessed 16 Jul 2021.

(7)      Microwave Remote Sensing, Govt of Canada, 01 Dec 2015, Accessed 16 Jul 2021.

(8)      Indian Remote Sensing Programme, Wikipedia, last Edited 08 Jul 2021, Accessed 16 Jul 2021.

(9)      The Saga of Indian Remote Sensing Satellite System, ISRO, DOS, Government of India, Accessed 16 Jul 2021.

(10)     Indian National Satellite System, Wikipedia, last Edited 16 May 2021, Accessed 16 Jul 2021.

(11)     Communication Satellites, ISRO, DOS, Government of India, Accessed 16 Jul 2021.

(12)     About GAGAN, GAGAN (GPS Aided Geo Augmentation Navigation): Redefining Navigation, Airport Authority of India, Accessed 16 Jul 2021.

(13)     Satellite Navigation, ISRO, DOS, Government of India, Accessed 16 Jul 2021.

(14)     Indian Regional Navigation Satellite System, Wikipedia, last Edited 07 Jun 2021, Accessed 16 Jul 2021.

(15)     Launchers, ISRO, DOS, Government of India, Accessed 16 Jul 2021.

(16)     Satellite Launch Vehicle, Wikipedia, last Edited 21 Jun 2021, Accessed 16 Jul 2021.

(17)     Augmented Satellite Launch Vehicle, Wikipedia, last Edited 30 Dec 2020, Accessed 16 Jul 2021.

(18)     Polar Satellite Launch Vehicle, Wikipedia, last Edited 26 Jun 2021, Accessed 16 Jul 2021.

(19)     Geosynchronous Satellite Launch Vehicle, Wikipedia, last Edited 10 Jul 2021, Accessed 16 Jul 2021.

(20)     Chandrayaan-1, Wikipedia, last Edited 08 Jul 2021, Accessed 16 Jul 2021.

(21)     Chandrayaan-2, Wikipedia, last Edited 29 Jun 2021, Accessed 29 Jun 2021.

(22)     Mars Orbiter Mission, Wikipedia, last Edited 09 Jul 2021, Accessed 16 Jul 2021.

(23)     High Thrust Cryogenic Engine (CE20) Development, ISRO, DOS, Government of India, Accessed 16 Jul 2021.

(24)     Reusable Launch Vehicle – Technology Demonstration Program (RLV-TD), ISRO, DOS, Government of India, Accessed 16 Jul 2021.

(25)     SSLV Manufacturing, NewSpace India Ltd, Accessed 16 Jul 2021.

(26)     Indian Space Research Organisation: Extra-Terrestrial Probes, Wikipedia, Accessed 16 Jul 2021.