Space Technology

Statement I is Correct: Axiom-4 is a private astronaut mission to the ISS specifically designed to carry out science and micro-gravity research payloads.

Statement II is Incorrect: Based on official classification, SpaDeX (Space Docking Experiment) is categorized as a technology demonstrator for autonomous docking; while it paves the way for a space station, it is not officially listed as a micro-gravity research mission in this context.

Statement III is Correct: Gaganyaan, India's flagship human spaceflight program, includes multiple payloads for micro-gravity experiments to be conducted by the Vyomanauts in low Earth orbit.

Note: After the release of the UPSC ANSWER KEY 2025, we have updated the correct answer to B.

Statement I: Correct *GAGAN is an Indian SBAS developed by ISRO and AAI to enhance GPS accuracy and integrity, crucial for aviation safety.*

Statement II: Correct *It improves GPS reliability and accuracy, enabling better air traffic management and safer, efficient navigation.*

Statement III: Incorrect *GAGAN's benefits extend beyond aviation to railways, roadways, maritime, agriculture, and disaster management.*

Correct Answer: Only Statements I and II are correct.

* Satellite navigation is based on the use of range measurements between navigational satellites and the user. Information about the satellite's coordinates is given to the user through a navigation signal. Range measurements are based on the calculation of the receiving signal time delay compared with the signals generated by the user equipment.

* Currently, there are four global systems viz., GPS from the USA, GLONASS from Russia, Galileo from the European Union, and BeiDou from China. In addition, there are two regional systems viz., NavIC from India and QZSS from Japan.

* Global navigation system caters to the users in the entire world, whereas the regional navigation system caters to the users in the limited service area.

Hence, option (D) is the correct answer.

Remote sensing is the process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance from the targeted area.

Statement 1 is correct. Satellite images and remote sensing data can indeed be used to estimate the chlorophyll content in vegetation. This is done by measuring the reflectance of light from the vegetation. The chlorophyll in plants absorbs light for photosynthesis, and the amount of light reflected back can give an estimate of the chlorophyll content.

Statement 2 is correct. Satellite images and remote sensing data can also be used to estimate greenhouse gas emissions. This is done by detecting the radiations emitted by the substances in the rice paddies.

Statement 3 is correct. Satellite images and remote sensing data can be used to measure land surface temperatures as well. This is done by detecting the infrared radiation emitted by the land surface.

Therefore, all three parameters can be measured or estimated using satellite images or remote sensing data.

Statement 1 is correct. PSLV (Polar Satellite Launch Vehicle) is primarily used to launch Earth observation/monitoring satellites, while GSLV (Geosynchronous Satellite Launch Vehicle) is designed to launch communication satellites into geosynchronous transfer orbits.

Statement 2 is incorrect. Satellites launched by PSLV are typically placed in polar or sun-synchronous orbits, which are not geosynchronous. These satellites appear to move across the sky as viewed from a particular location on Earth.

Statement 3 is incorrect. The GSLV Mk III is a three-stage launch vehicle, not a four-stage one. The first stage uses solid rocket motors, the second stage uses liquid rocket engines, and the third stage uses a cryogenic rocket engine.


GPS, or Global Positioning System, is a satellite-based navigation system that provides geolocation and time information to a GPS receiver anywhere on or near the Earth. It has a wide range of applications.

Statement 1 is correct. GPS is used in mobile phones for various purposes such as location tracking, navigation, and location-based services.

Statement 2 is correct. GPS is used in banking operations for ATM location services and for time-stamping transactions, which is crucial for maintaining accurate records.

Statement 3 is correct. GPS is used for time-stamping power system measurements, which is vital for grid stability and synchronization. Therefore, GPS technology can be used in all the three areas mentioned.

IRNSS is an independent regional navigation satellite system being developed by India.

Statement 1 is correct: The Indian Regional Navigation Satellite System (IRNSS) indeed has three satellites in geostationary orbits and four satellites in geosynchronous orbits.


Statement 2 is incorrect: It is designed to provide accurate position information service to users in India as well as the region extending up to 1500 km from its boundary, which is its primary service area. An Extended Service Area lies between primary service area and area enclosed by the rectangle from Latitude 30 deg South to 50 deg North, Longitude 30 deg East to 130 deg East.

Statement 3 is incorrect: While India has been working on enhancing the coverage of its navigation system, as of the given timeframe (2019), it does not have full global coverage. The system is primarily regional, although there are plans for augmentation and expansion.

Statement 1 is incorrect: AstroSat is India's first dedicated multi-wavelength space observatory aimed at studying celestial sources in X-ray, optical and UV spectral bands simultaneously. India is the 5th country to join the space observatory elite list after the USA, Russia, Japan, and Europe.

Statement 2 is incorrect: AstroSat with a lift-off mass of about 1513 kg was launched into a 650 km orbit inclined at an angle of 6 degrees to the equator by PSLV-C30.

Therefore, option D is the correct answer.

Statement 1 is correct: Mangalyaan is also called the Mars Orbiter Mission (MOM). This was its official designation.

Statement 2 is incorrect: India was not the second country to orbit Mars. Several countries had successfully sent spacecraft to Mars before Mangalyaan, including the USA, Russia, and the European Space Agency (ESA).

Statement 3 is correct: India was indeed the only country at that time to succeed in placing a spacecraft into Martian orbit on its very first attempt. This was a significant achievement for ISRO.

Hence, option C is the correct answer.

Assessment of crop productivity: IRS satellites capture data that helps assess crop health, growth stage, and potential yield. Locating groundwater resources: Remote sensing allows for studying geological features and identifying potential zones with underground water reserves. Mineral exploration: IRS data can reveal signatures of specific minerals on the Earth's surface, aiding in mineral exploration activities. Telecommunications: IRS satellites are not designed for telecommunication purposes. Geostationary satellites are typically used for this function. Traffic studies: While remote sensing can be used for some traffic studies (e.g., analyzing transportation infrastructure), it's not the primary application of IRS satellites.

Therefore, only 1,2 and 3 are primary applications of IRS satellites.

The Indira Gandhi Prize for Peace, Disarmament and Development for 2014 was presented to the Indian Space Research Organisation (ISRO).

- It was awarded in recognition of its path-breaking achievements, especially the Mars Orbiter Mission; its significant contributions in strengthening international cooperation in the peaceful uses of outer space etc.

- The award consists of a trophy made of banded Haematite Jasper, with a portrait of the late Prime Minister in the tradition of Jaipur miniature paintings, a cash award of Rs. 1 Crore and a Citation.

Pair 1 is incorrectly matched: The Cassini-Huygens mission was a joint NASA/ESA/ASI mission to study the planet Saturn and its system of rings and moons. The Huygens probe successfully landed on Saturn's largest moon, Titan.

Pair 2 is correctly matched: The MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) was a NASA spacecraft that orbited the planet Mercury from 2011 to 2015, studying its chemical composition, geology, and magnetic field.

Pair 3 is correctly matched: These twin NASA spacecraft were launched in 1977 to conduct a "Grand Tour" of the outer planets. They provided detailed images and data on Jupiter, Saturn, Uranus, and Neptune and are now continuing their journey into interstellar space.