Space Technology Innovations: Nanosatellites, Electric Propulsion, Satellite-Based Internet
Science & Technology › Space Technology and ISRO · Topic 12.11
Three innovations are changing space technology. Nanosatellites are very small satellites, with a mass of 1 to 10 kilograms, often built as CubeSats from 10-centimetre cubes called 1U units, and they cost far less to build and launch than large satellites. Electric propulsion drives a spacecraft by using electricity to accelerate charged particles, as in ion and Hall effect thrusters, which give a very high fuel efficiency but low thrust. Satellite-based internet uses large constellations of satellites in low Earth orbit, such as Starlink of SpaceX and OneWeb, to give broadband to places that cables do not reach, with a delay far shorter than that of geostationary satellites. India is developing its own rules for satellite communication services.
5 min read · UPSC Prelims · Science & Technology · Space Technology and ISRO
At a Glance
- Nanosatellite 1 to 10 kg
- CubeSat unit 10 cm cube, 1U
- Electric propulsion High efficiency, low thrust
- LEO internet Starlink, OneWeb
- Delay Far lower than GEO
- Exam link UPSC Prelims, Science & Technology: Space Technology and ISRO
Where Does It Fit?
This topic follows the private sector account. Many of the new companies work on these technologies, which lower the cost and widen the use of space. Previous topic: Private Sector Participation and Public-Private Collaboration in Space. Next topic: Remote Sensing Applications and Ground Segment Services.
What Are Small Satellites and How Are They Classed?
| Class | Mass and examples |
|---|---|
| Large satellite | More than 1,000 kg. Big communication satellites such as GSAT-11 |
| Medium satellite | 500 to 1,000 kg |
| Mini satellite | 100 to 500 kg |
| Microsatellite | 10 to 100 kg. Examples include Indian microsatellites such as INS-1A and 1B |
| Nanosatellite | 1 to 10 kg. CubeSats of 1U, 3U or 6U size. Often built by universities and start-ups |
| Picosatellite | 0.1 to 1 kg |
| Femtosatellite | Below 0.1 kg |
How Does Electric Propulsion Work and What Is Satellite Internet?
- Ion thruster: a gas such as xenon is ionised and the ions are accelerated by an electric field, giving a gentle but long lasting push
- Hall effect thruster: uses a magnetic field to trap electrons and a gas to make ions, widely used for station keeping of satellites
- Efficiency: electric thrusters can have a specific impulse of 1,500 to 3,000 seconds or more against about 450 for the best chemical engines
- Low thrust: they give only a small force, so the orbit rises slowly and they cannot launch a rocket from the ground
- Uses: station keeping, orbit raising, and deep space missions such as NASA’s Dawn probe
- Indian use: ISRO has used electric propulsion on communication satellites like GSAT-9 for orbit control, and has developed a stationary plasma thruster
- Satellite internet in LEO: hundreds or thousands of satellites at about 500 to 1,200 km give a delay of 20 to 40 milliseconds
- Starlink and others: SpaceX’s Starlink has several thousand satellites, OneWeb is owned by Eutelsat, and Amazon’s Project Kuiper is a planned third
What Else Should You Remember?
- CubeSat standard: developed in 1999 by California Polytechnic State University and Stanford University, so that students could build satellites
- Indian nanosatellites: ISRO’s INS-1C, university satellites like SRMSat and Jugnu, and the Student Satellite programme
- Rideshare launches: small satellites share rockets, as PSLV launches many together
- Constellation: a group of satellites that work together, which needs inter-satellite links and many launches
- Satcom in India: the Telecommunications Act, 2023 allows administrative allotment of satellite spectrum, and the regulators and IN-SPACe have been working on licensing. Check the latest status for Starlink and other firms
- Digital divide: satellite broadband can serve remote villages, islands and mountains, as in the Bharat Net project that uses fibre
- Concerns: sky brightness for astronomers, space debris, spectrum sharing and national security
- Space debris link: large constellations increase collisions risks, as in Space Junk and Graveyard Orbits
- Cost reduction: miniaturised electronics from phones and mass production reduce satellite cost
- Earth observation constellations: Indian firms plan fleets of small imaging satellites for frequent revisits, as in Hyperspectral Imaging Satellite and Water Propulsion System in CubeSats
- Reaction wheels: small satellites use wheels and magnetic torquers for pointing without fuel
- Limits: small satellites have limited power, life and payload size
- Nanosatellite risks: small satellites often have short lives and little manoeuvre ability, which adds to debris unless they are designed to deorbit quickly
- Direct to device: newer services aim to connect ordinary phones straight to satellites for text and emergency calls where towers are absent, which needs large antennas and new spectrum rules
Why Does It Matter for the Exam?
- Mass classes: micro, nano, pico
- Propulsion: ion versus Hall, high efficiency low thrust
- Constellations: Starlink and OneWeb
- Current affairs link: satcom licences and spectrum
- Common errors: saying that electric propulsion is used to launch from Earth
As an analytical point, small satellites and satellite internet lower the cost of using space and widen access, but need coordinated rules on spectrum, debris and security. Electric propulsion makes satellites lighter and longer lived.
Why Is This Topic Important?
- Classes Mass limits
- Propulsion Electric vs chemical
- Internet LEO constellations
What Came Next?
The next topic covers remote sensing applications and the ground segment. Next topic: Remote Sensing Applications and Ground Segment Services.
Key People and Terms
- CubeSat Standard small satellite
- Ion thruster Electric rocket engine
- Specific impulse Fuel efficiency
- Constellation Group of satellites
- Latency Signal delay
- Rideshare Shared launch
Exam Corner
Points to Remember
- Nanosatellite: 1 to 10 kg.
- 1U CubeSat: 10 cm cube.
- Electric thrusters: high efficiency, low thrust.
- LEO internet delay: about 20 to 40 ms.
- CubeSat standard: 1999.
Do Not Confuse With
- Ion and Hall thrusters Electric field versus magnetic field aided
- Nanosatellite and microsatellite 1 to 10 kg versus 10 to 100 kg
- LEO and GEO internet Low delay versus long delay
Memory Hook
Cube of ten centimetres, ions that push gently, constellations that bring the net.
Mains Angle
Questions ask about satellite classes and trends. These points help.
- Benefits Low cost and access
- Concerns Debris and spectrum
- India Policy readiness
A Question You May Face
An original practice question, not a past paper question.
“Discuss how nanosatellites, electric propulsion and satellite internet are changing the space sector, and the policy issues they raise for India.”
How to Answer
- Innovations Three trends.
- Benefits Cost and reach.
- Issues Debris, spectrum.
- Way Clear rules.
GS Relevance
Frequently Asked Questions
What is a nanosatellite?
A nanosatellite is a satellite with a mass of 1 to 10 kilograms. Many are CubeSats, built from standard 10-centimetre cubes called 1U units, and they are cheap to build and launch, often as extra payloads on larger rockets. Universities, start-ups and space agencies use them for experiments, Earth observation and communication.
How does an ion thruster work?
An ion thruster ionises a gas such as xenon and uses an electric field to accelerate the ions to very high speed, producing a small but steady thrust. It is very fuel efficient compared with chemical rockets, so satellites can use less propellant, but the low thrust means it cannot be used for launching from the ground.
What is satellite-based internet?
Satellite-based internet delivers broadband through satellites instead of cables or towers. Newer systems such as Starlink and OneWeb use large constellations in low Earth orbit at roughly 500 to 1,200 kilometres, which gives much lower delay than geostationary satellites and makes video calls and online work possible in remote areas.
Why are CubeSats popular?
CubeSats are popular because the standard size and parts lower the cost and the time to build a satellite. They can fly as secondary payloads on larger rockets, so students and small companies can get to space. They are used for training, technology tests, Earth observation and communication experiments.
What are the concerns about large satellite constellations?
Large constellations raise concerns about space debris and collision risk, the brightening of the night sky for astronomers, crowding of radio frequencies, and national security. They also need clear national rules on licensing and spectrum, which India is developing under the Telecommunications Act, 2023 and the Indian space policy.
PYQ Practice — Statement Analysis
1 A nanosatellite has a mass between 1 and 10 kg.
CubeSats are common.
2 Ion thrusters can be used to launch a rocket from the ground.
Their thrust is too low.
3 LEO satellite internet has lower delay than GEO satellite internet.
Because of shorter distance.
4 A 1U CubeSat is a 10 cm cube.
The basic unit.
Past Mains Questions on This Topic
This topic comes under Space Technology and ISRO. UPSC Mains questions asked on the matching syllabus topic, year-wise with marks:
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