Which orbit has a period of exactly one sidereal day and an inclination of 63.4 degrees?
- Molniya Orbit
- Tundra Orbit
- Halo Orbit
- Polar Orbit
Explanation: A Tundra orbit is a highly elliptical geosynchronous orbit used for high-latitude communication with a 24-hour period.
Which specific Lagrange point is used by the Aditya-L1 mission to observe the Sun continuously?
- L1 point
- L2 point
- L3 point
- L4 point
Explanation: The L1 (Lagrange Point 1) of the Sun-Earth system provides an uninterrupted view of the Sun without occultation by Earth.
What is 'Epoch' in the context of satellite tracking data (TLE)?
- Data speed
- Reference time
- Maximum altitude
- Satellite age
Explanation: In a Two-Line Element (TLE) set, the epoch is the specific point in time for which the orbital elements are calculated.
The James Webb Space Telescope (JWST) is located at which Lagrange point?
Explanation: JWST is at the L2 point, which allows it to stay in line with Earth while its sunshield blocks heat from the Sun and Earth.
What is the 'Semi-major axis' of a satellite's orbit?
- Minimum height
- Angular tilt
- Average distance
- Total speed
Explanation: The semi-major axis defines the size of the orbit and represents the average distance from the center of the Earth.
What is the approximate escape velocity required for a satellite to leave Earth's gravitational pull?
- 15.0 km/s
- 7.9 km/s
- 5.5 km/s
- 11.2 km/s
Explanation: Escape velocity is the minimum speed needed for a free, non-propelled object to escape from the gravitational influence of a massive body.
What is a 'Prograde' orbit in satellite mechanics?
- With Earth rotation
- Across the poles
- Against Earth rotation
- Leaving Earth orbit
Explanation: A prograde (or direct) orbit is one in which the satellite moves in the same direction as the Earth's rotation.
Which theory describes a chain reaction of satellite collisions in LEO creating a debris cloud?
- Kessler Syndrome
- Big Bang
- Doppler Effect
- Hawking Radiation
Explanation: The Kessler Syndrome is a scenario where the density of objects in LEO is high enough that collisions create more debris, making the orbit unusable.
What is the 'Delta-V' required for in satellite missions?
- Changing velocity
- Measuring distance
- Calculating mass
- Data encryption
Explanation: Delta-V is a measure of the impulse needed to perform a maneuver, such as changing orbits or landing.
What is the function of 'Thrusters' on a satellite already in orbit?
- Attitude control
- Data amplification
- Initial launch
- Solar charging
Explanation: Onboard thrusters are used for orientation (attitude) and small orbital corrections (station-keeping).
In satellite terminology, what is the 'Nadir'?
- Highest orbital point
- Lowest orbital speed
- Point directly below
- Point directly above
Explanation: Nadir is the direction pointing directly toward the center of the Earth from the satellite's perspective.
In which type of orbit is the International Space Station (ISS) currently located?
Explanation: The ISS orbits the Earth at an altitude of approximately 400-420 km, which is well within the Low Earth Orbit range.
What term defines the point in an elliptical orbit where the satellite is farthest from Earth?
- Apogee
- Perigee
- Equinox
- Solstice
Explanation: The apogee is the point in an orbit farthest from the center of the Earth.
What is the primary risk of 'Space Situational Awareness' (SSA) trying to mitigate?
- Launch delays
- Solar radiation
- Software bugs
- Orbital collisions
Explanation: SSA involves tracking space objects and debris to predict and prevent potential collisions between satellites.
Kepler's Second Law states that a line joining a satellite and Earth sweeps out what in equal intervals of time?
- Equal distances
- Equal masses
- Equal areas
- Equal velocities
Explanation: This law implies that satellites move faster when they are at perigee and slower when they are at apogee.
India's NavIC (IRNSS) constellation utilizes a combination of which two types of orbits?
- GEO and GSO
- LEO and GEO
- LEO and MEO
- MEO and GTO
Explanation: The NavIC system consists of 3 satellites in Geostationary Orbit (GEO) and 4 satellites in Geosynchronous Orbit (GSO).
A Sun-synchronous orbit relies on which natural phenomenon to maintain its orientation toward the Sun?
- Lunar tides
- Nodal precession
- Atmospheric drag
- Solar flares
Explanation: SSO uses the Earth's oblateness (bulge at the equator) to cause the orbit plane to precess at a rate that matches Earth's orbit around the Sun.
What is the approximate altitude of a satellite placed in a Geostationary Orbit (GEO)?
- 20,000 km
- 2,000 km
- 36,000 km
- 400 km
Explanation: A Geostationary Orbit is a circular orbit approximately 35,786 km (commonly rounded to 36,000 km) above the Earth's equator.
An orbit that passes over the equator at the same local solar time every day is called:
- Molniya
- Polar
- Sun-synchronous
- Geostationary
Explanation: Sun-synchronous orbits (SSO) ensure that the satellite sees the Earth under constant lighting conditions.
What is the approximate inclination of a satellite placed in a typical Polar Orbit?
- 0 degrees
- 90 degrees
- 180 degrees
- 45 degrees
Explanation: A polar orbit has an inclination of approximately 90 degrees, allowing the satellite to pass over the Earth's North and South poles.
A 'Hohmann Transfer' is an orbital maneuver used to move a satellite between which two entities?
- Two orbits
- Two stars
- Two planets
- Earth and Moon
Explanation: A Hohmann Transfer uses two engine impulses to move a spacecraft between two coplanar orbits of different altitudes.
According to Kepler's Third Law, the square of a satellite's orbital period is proportional to which value?
- Cube of radius
- Orbital velocity
- Square of radius
- Satellite mass
Explanation: Kepler's Third Law states that the square of the orbital period ($T^2$) is proportional to the cube of the semi-major axis ($a^3$) of its orbit.
What is the 'Argument of Perigee' in orbital mechanics?
- Fuel to weight
- Speed at perigee
- Orientation of orbit
- Height above poles
Explanation: It is an orbital element that defines the orientation of the elliptical orbit within its orbital plane.
What is the approximate orbital velocity of a satellite operating in a Low Earth Orbit?
- 11.2 km/s
- 7.8 km/s
- 3 km/s
- 1.5 km/s
Explanation: Satellites in LEO travel at approximately 7.8 km/s (around 28,000 km/h) to maintain their altitude.
What is the primary function of 'Station-keeping' in satellite operations?
- Transmitting data
- Generating power
- Maintaining position
- Cooling sensors
Explanation: Station-keeping involves using small thrusters to counteract perturbations and keep a satellite in its assigned orbital slot.
Which natural force causes the 'J2 Perturbation' due to Earth's non-spherical shape?
- Equatorial bulge
- Atmospheric wind
- Oceanic tides
- Magnetic poles
Explanation: The Earth is an oblate spheroid; the extra mass at the equator (J2 effect) causes the orbital plane of satellites to precess.
Which orbit is used for 'Broadcasting' to ensure the antenna on the ground doesn't need to move?
Explanation: Geostationary satellites appear fixed in the sky, allowing permanent satellite dishes on homes to stay pointed at one spot.
Low Earth Orbit (LEO) is generally defined as being within which altitude range above the Earth's surface?
- 160-2000 km
- 100-500 km
- 2000-35786 km
- Above 36000 km
Explanation: LEO is the region of space around Earth with an altitude of 2,000 km or less, though most are between 160 km and 1,000 km.
What is the primary function of a Geostationary Transfer Orbit (GTO)?
- Final mission
- Observation
- Staging orbit
- Debris removal
Explanation: GTO is an elliptical orbit used to transition a satellite from a low altitude to its final geostationary destination.
Why do most satellites launch in an 'Eastward' direction?
- Avoid ocean debris
- Better solar power
- Shorter travel time
- Utilize Earth's rotation
Explanation: Launching eastward takes advantage of the Earth's rotational velocity, which provides a 'free' boost to the rocket's speed.
What is the 'Ground Track' of a satellite?
- Launch trajectory
- Radio signal range
- Fuel consumption map
- Path on Earth
Explanation: The ground track is the projection of the satellite's orbital path onto the surface of the Earth.
What is 'RAAN' (Right Ascension of the Ascending Node)?
- Vertical height
- Horizontal orientation
- Launch angle
- Orbital velocity
Explanation: RAAN defines the 'longitude' of the point where the satellite crosses the equator moving north.
What does 'De-orbiting' involve at the end of a LEO satellite's mission?
- Exploding the craft
- Solar escape
- Moving to GEO
- Atmospheric re-entry
Explanation: De-orbiting is the process of slowing down a satellite so it enters the Earth's atmosphere and burns up, reducing space debris.
Which international body manages the allocation of orbital slots and frequencies in Geostationary Orbit?
Explanation: The International Telecommunication Union (ITU) coordinates global radio spectrum and satellite orbits to prevent interference.
What happens to a satellite if its speed exceeds the 'Escape Velocity'?
- Crashes into Earth
- Becomes stationary
- Leaves Earth orbit
- Orbits the Moon
Explanation: Escape velocity is the speed at which the kinetic energy of an object is enough to overcome the Earth's gravitational pull permanently.
A temporary orbit used while testing systems or waiting for a specific transfer window is known as a:
- Graveyard orbit
- Stable orbit
- Parking orbit
- Transfer orbit
Explanation: Parking orbits are used during launch sequences before the spacecraft is boosted into a higher or interplanetary trajectory.
The 'Clarke Belt' is another name for which specific type of orbit?
- Low Earth Orbit
- Geostationary Orbit
- Polar Orbit
- Medium Earth Orbit
Explanation: Named after Arthur C. Clarke, who first popularized the idea of using GEO for global communications in 1945.
How does the orbital velocity of a satellite change as its distance from the Earth increases?
- It decreases
- It increases
- Becomes zero
- Remains constant
Explanation: According to orbital mechanics, the further a satellite is from the Earth, the slower its required orbital velocity to stay in a stable orbit.
Which factor primarily causes orbital decay for satellites operating in Low Earth Orbit?
- Atmospheric drag
- Lunar gravity
- Magnetic pull
- Solar wind
Explanation: In LEO, the thin upper atmosphere still exerts a drag force on satellites, causing them to lose speed and eventually re-enter the atmosphere.
What is the orbital period of a semi-synchronous orbit, such as the one used by GPS satellites?
- 90 minutes
- 12 hours
- 24 hours
- 6 hours
Explanation: A semi-synchronous orbit has a period of half a sidereal day (approx. 12 hours) and is circular at an altitude of about 20,200 km.
What does the 'Eccentricity' of an orbit measure?
- Orbital height
- Orbital shape
- Orbital speed
- Orbital tilt
Explanation: Eccentricity (e) defines how much an orbit deviates from a perfect circle; e=0 is circular, while e > 0 is elliptical.
What is the 'Line of Nodes' in an orbit?
- Radio signal line
- Earth-Sun axis
- Equatorial intersection
- Highest point path
Explanation: The line of nodes is the intersection of the orbital plane with the Earth's equatorial plane.
What is the main advantage of placing a remote sensing satellite in a Sun-synchronous Orbit (SSO)?
- Global coverage
- Zero latency
- Low cost
- Constant lighting
Explanation: SSO ensures the satellite crosses the equator at the same local solar time, providing uniform shadow and lighting conditions for image comparison.
What determines the 'Footprint' of a satellite?
- Physical size
- Coverage area
- Launch weight
- Antenna length
Explanation: A satellite's footprint is the specific area on Earth's surface within which the satellite's signals can be received.
Which type of orbit is specifically used for Earth-observation and remote-sensing satellites to ensure consistent lighting?
- Medium Earth Orbit
- Geostationary Orbit
- Molniya Orbit
- Sun-synchronous Orbit
Explanation: Sun-synchronous Orbit (SSO) allows a satellite to pass over a section of the Earth at the same local solar time, providing consistent lighting for photography.
Which highly elliptical orbit is designed to provide communication coverage for high-latitude polar regions?
- Equatorial Orbit
- Sun-synchronous Orbit
- Molniya Orbit
- Geostationary Orbit
Explanation: Molniya orbits are highly elliptical orbits used by Russia and others to provide communications to regions near the poles where GEO satellites cannot reach.
An orbit that lies directly above the Earth's equator with zero inclination is known as:
- Polar Orbit
- Inclined Orbit
- Molniya Orbit
- Equatorial Orbit
Explanation: Equatorial orbits have an inclination of 0 degrees and stay directly above the Earth's equator.
What is the orbital period of a satellite placed in a Geostationary Orbit?
- One month
- 12 hours
- 90 minutes
- 24 hours
Explanation: A GEO satellite's period matches Earth's sidereal rotation period (approx. 23 hours, 56 minutes), appearing stationary from Earth.
What is 'Orbital Perturbation'?
- Signal frequency shift
- Satellite battery drain
- Deviation from path
- Launch phase speed
Explanation: Perturbations are small changes in a satellite's orbit caused by non-ideal forces like Earth's oblateness or lunar gravity.
What term defines the specific point in an elliptical orbit where the satellite is closest to Earth?
- Zenith
- Apogee
- Perigee
- Nadir
Explanation: In an elliptical orbit around Earth, the perigee is the point of minimum distance between the satellite and the Earth's center.
Which orbit is typically used for 'Spy Satellites' to get high-resolution images of the Earth's surface?
- Medium Earth Orbit
- Low Earth Orbit
- Graveyard Orbit
- Geosynchronous Orbit
Explanation: LEO is preferred for reconnaissance because the closer proximity to Earth allows for higher-resolution optical and radar imaging.
Which radiation belts must MEO satellites be specifically hardened to withstand?
- Van Allen belts
- Oort clouds
- Kuiper belts
- Asteroid belts
Explanation: The Van Allen radiation belts are zones of energetic charged particles trapped by Earth's magnetic field, located primarily in the MEO region.
Which phenomenon causes 'Signal Latency' in Geostationary communication?
- High altitude
- Satellite weight
- Solar flares
- Atmospheric rain
Explanation: Because GEO is 36,000 km away, the round-trip travel time for light/radio signals causes a delay of about 250 milliseconds.
What is an orbit that moves in the opposite direction of the Earth's rotation called?
- Prograde orbit
- Polar orbit
- Halo orbit
- Retrograde orbit
Explanation: A prograde orbit follows Earth's rotation (west to east), while a retrograde orbit moves against it (east to west).
What is the key difference between a Geosynchronous (GSO) and a Geostationary (GEO) orbit?
- Orbital altitude
- Satellite mass
- Orbital inclination
- Orbital period
Explanation: While both have a 24-hour period, GEO must have zero inclination (above the equator), whereas GSO can be inclined.
Medium Earth Orbit (MEO) is the primary location for which specific type of satellite constellation?
- Spy satellites
- TV satellites
- Weather satellites
- Navigation satellites
Explanation: GPS (USA), GLONASS (Russia), and Galileo (Europe) constellations are primarily located in MEO at altitudes around 20,000 km.
Which term describes the situation where an orbiting body always shows the same face to the primary body?
- Axial tilt
- Orbital resonance
- Tidal locking
- Synchronous rotation
Explanation: The Moon is tidally locked to Earth, which is why we always see the same side of it. Some satellites use similar principles for stability.
Where are satellites moved at the end of their operational life to avoid creating debris in useful orbits?
- Graveyard orbit
- Low orbit
- Lunar orbit
- Atmosphere
Explanation: A graveyard orbit, also called a disposal orbit, is located significantly above the common operational orbits like GEO.
Which specific orbital parameter defines the 'tilt' of the orbit relative to the equator?
- Eccentricity
- Right ascension
- Semi-major axis
- Inclination
Explanation: Inclination is the angle between the orbital plane and the Earth's equatorial plane.
Which Lagrange points are considered 'Stable', allowing objects to stay there with minimal fuel?
- L1 and L2
- L2 and L3
- L4 and L5
- L1 and L3
Explanation: L4 and L5 are stable points where objects (like Trojan asteroids) can remain naturally trapped; L1, L2, and L3 are unstable.