# Lunar Trajectories Questions and Answers – Important Parameters for Trajectories

This set of Spaceflight Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Important Parameters for Trajectories”.

1. What is the value of the gravitational parameter of the moon?
a) 2.84510 × 102 km3/sec2
b) 3.41245 × 103 km3/sec2
c) 4.90287 × 103 km3/sec2
d) 5.64512 × 104 km3/sec2

Explanation: μm is known as the moon’s gravitational parameter which is computed using the formulas:
μm = $$\frac{\mu_\oplus}{81.3}$$ = 4.90287 × 103 km3/sec2
Where moon’s mass is 1/81.3 of the mass of the Earth.

2. Which of these is not a restriction while carrying out lunar missions?
a) Declination of moon
b) Lighting conditions
c) Launch site direction
d) Moon’s rotational speed

Explanation: There are several design restrictions which are there for carrying out luncar missions. This includes, phases of the moon which determines the lighting conditions, declination of moon and direction of launch from the particular site.

3. Which of these parameters is used to determine the acceptable launch time?
a) Inclination
b) Geocentric sweep angle
c) Injection speed
d) Launch time

Explanation: One of the most important parameter which is used to deciding the acceptable launch time is geocentric sweep angle. This is the angle swept by the spacecraft from launch to the lunar intercept.

4. Which of these parameters is not required for computing the time of flight to the moon’s sphere of influence?
a) Parameter p
b) Eccentricity
c) Semi-majpr axis
d) Angular velocity

Explanation: The parameter required in order to complute the time of flight to the moon’s sphere of influence is-parameter p, eccentricity, semi-major axis and eccentric anomaly.

5. What should the launch azimuth for lunar missions?
a) 30° – 100°
b) 40° – 115°
c) 20° – 95°
d) 15° – 150°

Explanation: There’s a set launch azimuth for lunar missions. It should lie between 40° and 115° which has been specified by the Eastern Test Range Safety requirements.

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