Correct Answer :   1 light year

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Explanation : Solar system is the volume of space around the sun which extends up to 1 light year from the sun. This is the region where the planets and celestial bodies orbit.

Correct Answer :   99.86%

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Explanation : Sun is the densest material in the solar system and makes up to 99.86% of the solar system which is most of it. Its mass is as much as 332,900 Earth masses.

Correct Answer :   Solar flares

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Explanation : There’s a cyclic solar activity which occurs after every 11 year. This leads to massive solar flares which are high energy solar particles that interacts with earth’s atmosphere. This leads to auroral effects at the poles.

Correct Answer :   Magnesium

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Explanation : Meteor which glowing takes different hues of colours based on the metal that predominates other metal present in it. As the meteor is ablaze and ionizes, the colour is emitted. When the metal content is sodium, it emits orange-yellow, when it is iron, it reflects yellow colour, in case of magnesium it shows blue-green colour and when there’s presence of calcium, it emits violet colour.

Correct Answer :   Ceres

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Explanation : Kuiper belt is a region of millions of asteroid present between Mars and Jupiter. It has 4 large asteroid which makes up most of its mass. Among the four, Ceres is the largest object with diameter of 940 km. It is considered to be the 25th largest celestial body present in the solar system.

Correct Answer :   10 hours

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Explanation : Jupiter is among the 4 Jovian planets which are slightly oblong unlike the terrestrial planets. They have a faster rotation period which flattens out the spherical shape making it more oblate. Jupiter, Saturn have a rotation period of 10 hours whereas Uranus and Neptune have rotation period of 16-17 hours.

Correct Answer :   Mercury

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Explanation : All inner and outer planets have gaseous atmosphere present except for Mercury and Pluto. Instead of atmosphere, Mercury consists of an exosphere composed of atoms which are blasted from the surface by solar wind and striking meteoroids.

Correct Answer :   Beyond Neptune

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Explanation : Kuiper belt is a donut shaped region of icy celestial objects that are leftovers from the solar system’s history. It is larger than the asteroid belt which is located between Mars and Jupiter. This is located beyond Neptune and comprises of 3 dwarf planets.

Correct Answer :   Between Mars and Jupiter

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Explanation : There’s a region in the solar system which contains millions of asteroids known as the asteroid belt. This is located between Mars and Jupiter. The total mass of the Kuiper belt is still less compared to Pluto’s mass and is thinly distributed making it possible for spacecrafts travelling through it without any collision.

Correct Answer :   Meteorite

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Explanation : Meteorite is a solid debris present in the solar system which is a result of aftermath from a collision of a comet, asteroid. They tend to travel to the planet or moon’s surface by surviving through the atmosphere. While entering the planet’s atmosphere, it becomes a meteor which glows up due to the friction causing it to radiate heat and energy.

Correct Answer :   Oort cloud

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Explanation : Oort cloud is a theoretical cloud which surrounds sun at distance ranging from 2000-200,00 AU. This lies beyond the heliosphere and marks the end of the solar system boundary.

Correct Answer :   Comet

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Explanation : Comets are very small objects that are made up of ice, dust and gasses. When they travel close to sun, it releases the gases forming a tail. These tails can be as long as 10⁸ km.

Correct Answer :   63.4 deg and 116.6 deg

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Explanation : When the inclination of the orbit is 63.4 deg and 116.6 deg, the orbit is known to be critically inclined. At these angles the apse line which is an imaginary line joining the two apsides does not move.

Correct Answer :   Least deviations of eccentricity and argument of pericenter

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Explanation : The critically inclined orbits have been of interest in artificial satellite theory. They have the lest deviations of eccentricity and argument of periapsis from the initial values. This makes it preferential for space missions.

Correct Answer :   Earth’s oblateness term J2

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Explanation : The critical inclinations’ primary assumption is that the oblateness term J2 is dominant over other harmonic coefficients: J3, J4, J5. This assumption is valid only for large celestial bodies such as Earth, Mars, Moon etc.

Correct Answer :   3

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Explanation : Due to its highly eccentric orbit, satellites in Tundra orbit stay in high-latitude region for longer time periods of the time at apogee. Two satellites are required in Tundra orbit to provide continuous communication with earth’s receiving communication end.

Correct Answer :   Molniya orbit

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Explanation : Molniya orbit is an example of critically inclined orbit. It is highly eccentric and highly elliptical orbit which has an inclination of 63.4 degrees.

Correct Answer :   Supertundra orbit

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Explanation : The Tundra orbit is a highly elliptical and critically inclined orbit which makes a figure-8 shape. A variant of this orbit is called Supertundra orbit which instead of figure-8 makes a teardrop shape.

Correct Answer :   Half the sidereal day

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Explanation : For the geometry of the ground track of Molniya orbit to repeat after every 24 hours, the time period has to be half of the sidereal day to keep longitudes of the apogee constant.

Correct Answer :   J2 Perturbation

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Explanation : Earth’s not a complete spherical body, instead it’s equator is 21 km larger than radius at the poles. This oblateness effect causes perturbing forces on object orbiting the earth. This perturbing force based on oblate Earth is known as J2 Perturbations.

Correct Answer :   2

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Explanation : Out of 6 orbital elements that define the orbit around the earth, 2 are affected by the J2 perturbations. These are Right Ascension of the Ascending Node Ω and Argument of Perigee ω.

Correct Answer :   Giant planets

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Explanation : J3 is zero for the giant planets since the plasticity of these planets produces only zonal coefficients of J2n (symmetry relative to the equatorial plane or symmetry between north and south).

Correct Answer :   Inclination

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Explanation : Jr perturbation has an impact on the orbital inclination. Unlike J2 perturbation, it has very weak effect on the right of ascension and argument of perigee. The disturbance effects of J3 perturbations on the argument of perigee, right ascension and eccentricity are weakened when the eccentricity increases such as for the frozen orbits (Molniya or Tundra orbit).

Correct Answer :   Mainting fixed distance between two spacecrafts

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Explanation : Station-kepping is the process of keeping a spacecraft/satellite at the fixed distance from another spacecraft. Various maneuvers have to be made to keep this distance fixed.

Correct Answer :   Spacecraft’s cross-sectional area

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Explanation : In order to maintain the constant distance between the two spacecrafts’ it is essential to counter the perturbation forces. These are caused due to solar radiation presssure, gravitational field from the moon and sun and earth’s oblateness.

Correct Answer :   Prevent orbital period shortening

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Explanation : When a spacecraft re-enters the earth’s atmosphere, it is essential to keep the orbit in sync with the earth’s rotation else the orbital time period will increase.

Correct Answer :   Atmospheric drag

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Explanation : The International Space Stations orbits the Earth in the Low Earth Orbit. It is at a distance of 330-410 km. Due to the presence of atmospheric drag, ISS is continuously losing its orbital energy which is countered by providing thrust to maintain the orbit.

Correct Answer :   Hohmann transfer

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Explanation : During interplanetary trajectory involving spacecraft to move from one planet to another, Hohmann transfer is the most energy efficient transfer. The departure from the first planet is at the periapsis and the arrival is at the apoasis of the second planet’s orbit.

Correct Answer :   Negative

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Explanation : The delta-v required to move the spacecraft from the outer planet to the inner planet is always negative because departure point is at the aphelion and the arrival point is at the perihelion. The speed of the spacecraft has to be reduced in otder to enter a lower- energy transfer orbit.

Correct Answer :   Patched-conic method

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Explanation : For carrying out interplanetary missions, the patched conic method is employed to divide the mission into three parts. The basic aspect of these missions is that they are considered to be Hohmann transfer.

Correct Answer :   3

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Explanation : Using the patched-conic method, the mission is divided into three parts-hyperbolic departure trajectory which is relative to the home planet, cruise ellipse relative to sun and finally the hyperbolic arrival of the trajectory relative to the target plane.

Correct Answer :   Hyperbolic

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Explanation : In order to begin an interplanetary cruise, spacecraft first needs to escape the earth’s gravitational pull. The transition from near-earth space to interplanetary space is done using a hyperbolic departure trajectory. This helps the spacecraft in crossing the fictitious boundary known as Earth’s Sphere of Influence (SOI).

Correct Answer :   Fictitious boundary for 2-body motion about a planet

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Explanation : Sphere of Influence is a fictitious boundary where when the satellite enters, its orbit can be approximated by the two-body problem with the planet as the central body. It cannot be used to represent the motion of N-body gravity field.

Correct Answer :   149,597,871 km

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Explanation : Since the distances in heliocentric orbits are very large, the distances are referred in terms of AU (Astronomical unit) rather than kilometers. 1AU = 149,597,871 km.

Correct Answer :   Hyperbolic

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Explanation : The arrival trajectory inside the target planet’s sphere of influence is done using a hyperbolic orbit which is analyzed in inertial planet-centered frame. As soon as the spacecraft enters the target planet’s sphere of influence, the sun’s gravity is turned off and planet’s gravity is turned on.

Correct Answer :   Ratio of perturbing acceleration and central-body acceleration

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Explanation : According to Laplace, Sphere of Influence (SOI) is described as the ratio of perturbing acceleration and central-body acceleration.

Correct Answer :   Elliptic

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Explanation : In the heliocentric phase of the patched conic method, the spacecraft follows the elliptical transfer orbit where sun is considered as the primary gravitational body. The interplanetary cruise is analyzed by two-body mechanics in heliocentric0ecliptic coordinate frame.