UPSC Prelims Practice Questions — PM congratulates ISRO scientists and engineers on successful launch of GSLV-F18 carrying NVS-03

Q1. With reference to how a satellite navigation receiver determines its position, consider the following statements: Which of the statements given above is/are correct?

  1. A receiver needs signals from a fourth satellite because the offset between its own clock and satellite time is an additional unknown that must be solved for.
  2. If a receiver's clock were perfectly synchronised with satellite time, ranges from three satellites would in principle be enough to fix its position.
  3. Each satellite's signal fixes exactly one of the user's coordinates (latitude, longitude or altitude), which is why several satellites must be tracked together.
  • A. 2 and 3 only
  • B. 1 only
  • C. 1, 2 and 3
  • D. 1 and 2 only

Q2. With reference to GAGAN and NavIC, consider the following statements: Which of the statements given above are correct?

  1. GAGAN broadcasts correction and integrity messages that improve the use of GPS signals.
  2. GAGAN can provide an aircraft with its position even when GPS signals are unavailable.
  3. NavIC needs GPS signals to compute a user's position within its primary service area.
  4. NavIC, as designed, does not provide the integrity information required for safety-of-life aviation operations.
  • A. 1 and 4 only
  • B. 2 and 3 only
  • C. 1 and 2 only
  • D. 3 and 4 only

Q3. NavIC's constellation is designed with three satellites in geostationary orbit and four in geosynchronous orbits inclined at 29°. Its primary service area is India and a region extending about 1,500 km beyond it. Which of the following inferences can be drawn from the above?

  1. To an observer in India, all seven NavIC satellites would appear fixed at one point in the sky.
  2. Because every satellite in the constellation has an orbital period equal to one rotation of the Earth, a small constellation can keep a limited region continuously covered.
  3. A user in South America cannot expect standalone positioning from NavIC of the kind available within India.
  • A. 1 and 2 only
  • B. 2 and 3 only
  • C. 3 only
  • D. 1, 2 and 3

Q4. Consider the following statements: Which of the following is correct in respect of the above statements?

  1. Every navigation satellite of a system such as NavIC must carry highly stable atomic clocks rather than ordinary onboard clocks.
  2. A user's distance from a navigation satellite is calculated from the time delay of the received signal, so even a tiny timing error turns into a significant range error.
  • A. Both Statement-I and Statement-II are correct and Statement-II explains Statement-I
  • B. Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I
  • C. Statement-I is correct, but Statement-II is incorrect
  • D. Statement-I is incorrect, but Statement-II is correct

Q5. With reference to placing a navigation satellite in its operational orbit using GSLV, consider the following statements: Which of the statements given above are correct?

  1. The launch vehicle's upper stage releases the satellite in an elliptical transfer orbit, and the satellite later fires its own engine near apogee to circularise its orbit.
  2. A satellite in a geosynchronous transfer orbit already completes one revolution in the time the Earth takes to rotate once, so it needs only a change of inclination.
  3. A geostationary orbit is a geosynchronous orbit with zero inclination, whereas NavIC also uses geosynchronous orbits inclined to the equator.
  • A. 2 and 3 only
  • B. 1 and 2 only
  • C. 1 and 3 only
  • D. 1, 2 and 3

Q6. The first-generation IRNSS satellites broadcast navigation signals in the L5 and S bands, while the second-generation NVS satellites add an L1-band signal. What is the main purpose of this addition?

  • A. To transmit in a band also used by GPS, widening the range of receivers that can use NavIC
  • B. To replace the S-band signal, which the first-generation satellites were unable to transmit
  • C. To extend NavIC's primary service area from a regional footprint to global coverage
  • D. To let NavIC broadcast integrity messages certified for safety-of-life civil aviation

Q7. Which design feature of GSLV Mk II, the vehicle that launched all second-generation NavIC satellites, enables it to place satellites of about two tonnes into a geosynchronous transfer orbit?

  • A. A cluster of solid strap-on motors that carries the satellite straight into its final circular orbit
  • B. An air-breathing scramjet stage that draws atmospheric oxygen to cut the oxidiser mass on board
  • C. A core stage burning refined kerosene with liquid oxygen, giving the vehicle very high thrust at lift-off
  • D. An upper stage burning liquid hydrogen with liquid oxygen, giving the payload high velocity at separation