This set covers satellite orbits, India's launch vehicles and the major ISRO missions that appear regularly in UPSC Prelims. Questions on space technology test both basic concepts and awareness of India's programme, so knowing the facts behind each mission is useful.
How to practise: read each question and tap the option you think is correct. You will see right away whether you got it, along with a short explanation, and your score is tracked at the bottom of the screen. This set has 15 questions.
Topics covered in this set
- Geostationary, sun-synchronous and halo orbits
- PSLV, GSLV, LVM3 and SSLV launch vehicles
- Cryogenic engines
- Chandrayaan-1 and Chandrayaan-3
- Mangalyaan and Aditya-L1
- NavIC, Gaganyaan and SpaDeX
UPSC Science and Technology MCQs with answers and explanations
Q1. Which of the following is correct about a geostationary orbit?
a) It lies about 35,786 km above the equator and its period equals one rotation of the Earth
b) It passes over both the North and South Poles on every revolution
c) It lies at an altitude of about 500 km and is used mainly for imaging
d) A satellite in it moves from east to west relative to the Earth's surface
Q2. Why are most remote sensing satellites placed in a sun-synchronous orbit?
a) It keeps the satellite fixed over one point on the equator
b) It lets the satellite pass over a given place at the same local solar time, giving similar lighting for images
c) It is the highest orbit that a launch vehicle can reach
d) It keeps the satellite permanently in the Earth's shadow
Q3. Which of the following is correct about the Polar Satellite Launch Vehicle (PSLV)?
a) It uses a cryogenic engine in its first stage
b) It has only two stages, both using liquid fuel
c) It has four stages that alternate between solid and liquid propulsion
d) It can only place satellites in geostationary orbit
Q4. The indigenous cryogenic upper stage used in ISRO's GSLV burns which combination of propellants?
a) Kerosene and nitrogen tetroxide
b) Solid HTPB and ammonium perchlorate
c) Hydrazine and nitrogen tetroxide
d) Liquid hydrogen and liquid oxygen
Q5. Which launch vehicle placed Chandrayaan-3 into orbit in July 2023?
a) LVM3
b) PSLV-XL
c) SSLV
d) GSLV Mk II
Q6. Which of the following is correct about the Small Satellite Launch Vehicle (SSLV)?
a) It is a reusable launch vehicle that lands vertically
b) It uses three solid stages and a liquid velocity trimming module, for small satellites to low Earth orbit
c) It was designed to place 4-tonne satellites in geostationary orbit
d) It uses a semi-cryogenic engine in all its stages
Q7. With reference to Chandrayaan-3, consider its landing in August 2023. Which statement is correct?
a) The lander touched down near the Moon's north pole
b) It was India's first attempt to orbit the Moon
c) India became the first country to soft-land near the lunar south pole
d) It carried an orbiter, a lander and an impactor but no rover
Q8. Chandrayaan-1 is remembered mainly for which scientific contribution?
a) Landing the first Indian rover on the Moon
b) Returning lunar soil samples to Earth
c) Placing a satellite at the Earth-Moon L2 point
d) Helping detect water molecules on the lunar surface
Q9. Which of the following is correct about the Mars Orbiter Mission (Mangalyaan)?
a) It was launched by PSLV and made India the first country to reach Mars orbit in its first attempt
b) It was launched by LVM3 and carried a rover to the Martian surface
c) It was a joint mission of ISRO and NASA
d) It failed to reach Mars orbit but studied Mars during a flyby
Q10. Aditya-L1, India's first dedicated solar mission, observes the Sun from which location?
a) A low Earth orbit at about 600 km
b) A halo orbit around the Sun-Earth L1 point, about 1.5 million km from Earth
c) An orbit around the Moon
d) A geostationary orbit above India
Q11. Which of the following best describes a Lagrange point?
a) A point where a spacecraft has zero gravity acting on it
b) The point of an orbit closest to the Earth
c) A position where the gravity of two large bodies and the orbital motion balance, so a small object keeps a fixed position relative to both
d) The altitude at which the Earth's atmosphere ends
Q12. Which of the following is correct about NavIC?
a) It is a global navigation system covering the whole Earth like GPS
b) It uses only satellites in low Earth orbit
c) It is operated jointly by India and Russia
d) It is a regional navigation system covering India and about 1,500 km around it
Q13. In the Gaganyaan programme, what is the main role of the crew escape system?
a) To pull the crew module away from the launch vehicle quickly in an emergency
b) To generate electricity for the crew module in orbit
c) To slow the crew module using parachutes after re-entry
d) To dock the crew module with a space station
Q14. What did ISRO's SpaDeX mission demonstrate in January 2025?
a) The first Indian human spaceflight
b) Docking of two satellites in orbit, making India the fourth country to do so
c) Landing of a rover on Mars
d) A reusable rocket booster landing at sea
Q15. Why is a launch site close to the equator, such as Sriharikota, an advantage for eastward launches?
a) Air resistance is lowest near the equator
b) Gravity is strongest near the equator
c) The Earth's rotational speed is highest near the equator, giving the rocket an extra eastward boost
d) The magnetic field near the equator pushes rockets upward
Quick revision notes
- A geostationary orbit is about 35,786 km above the equator, with a period equal to one Earth rotation.
- Sun-synchronous orbits are near-polar and give constant lighting for remote sensing images.
- PSLV has four stages (solid, liquid, solid, liquid), and the GSLV upper stage is cryogenic using liquid hydrogen and liquid oxygen.
- Chandrayaan-3 landed near the lunar south pole on 23 August 2023, launched by LVM3.
- Mangalyaan (PSLV-C25, 2013) reached Mars orbit in 2014 in its first attempt, and Aditya-L1 (PSLV-C57, 2023) reached its L1 halo orbit in January 2024.
- SpaDeX achieved satellite docking on 16 January 2025, making India the fourth country to dock in space.
Frequently asked questions
What is the difference between geostationary and geosynchronous orbits?
Both have a period equal to one Earth rotation. A geostationary orbit is a special geosynchronous orbit that lies over the equator with zero inclination, so the satellite appears fixed in the sky. NavIC uses both types.
Why is a cryogenic engine harder to build?
Liquid hydrogen and liquid oxygen must be stored at extremely low temperatures, which needs special materials and insulation. The engine must also handle very large temperature differences between the cold propellants and hot combustion. In return it gives higher efficiency than solid or earth-storable liquid fuels.
Why do UPSC questions focus on the launch vehicle used for a mission?
Each launcher has a distinct capacity and orbit range, so linking missions to launchers tests real understanding. For example, PSLV launched Chandrayaan-1, Mangalyaan and Aditya-L1, while LVM3 launched Chandrayaan-3. Remembering these pairs helps eliminate options quickly.
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