NASA Orbital Mechanics Certification Test

30 Questions • Multiple Choice • NASA Style

1. What keeps a spacecraft in orbit around Earth?

A. Continuous engine thrust B. Balance between velocity and gravity C. Atmospheric lift D. Earth's magnetic field

2. Which maneuver transfers a spacecraft between two circular orbits using two burns?

A. Oberth Maneuver B. Hohmann Transfer C. Gravity Turn D. Plane Change

3. Delta-v measures...

A. Distance traveled B. Required change in velocity C. Rocket mass D. Orbital period

4. Apoapsis is...

A. Closest point B. Highest point of an orbit C. Escape trajectory D. Orbital inclination

5. Periapsis is...

A. Closest point in an orbit B. Highest altitude C. Plane angle D. Escape velocity

6. Which law explains planetary motion?

A. Kepler's Laws B. Boyle's Law C. Ohm's Law D. Hooke's Law

7. A plane change is usually most efficient...

A. At periapsis B. At apoapsis C. During launch only D. During atmospheric flight

8. What is TWR?

A. Thermal Weight Ratio B. Thrust-to-Weight Ratio C. Total Warp Rating D. Transfer Window Radius

9. What does ISP stand for in rocketry?

A. Internal Space Pressure B. Impulse Stability Parameter C. Specific Impulse D. Integrated Space Propulsion

10. The Oberth Effect is strongest...

A. At the highest point of an orbit B. At the lowest point where velocity is highest C. In deep space D. During reentry

11. A gravity assist uses...

A. Atmospheric drag B. A planet's motion and gravity C. Rocket exhaust recycling D. Solar wind

12. Escape velocity means...

A. The speed needed to leave a body's gravity without further propulsion B. Maximum rocket speed C. Orbital speed D. Atmospheric speed limit

13. Which orbit has zero eccentricity?

A. Hyperbolic B. Elliptical C. Circular D. Escape

14. Which parameter describes how tilted an orbit is?

A. Inclination B. Apoapsis C. Periapsis D. Eccentricity

15. A geostationary satellite orbits approximately every...

A. 90 minutes B. 12 hours C. 24 hours D. 7 days

16. Which stage of a rocket is usually discarded first?

A. Upper stage B. Payload fairing C. First stage D. Spacecraft

17. What primarily determines a spacecraft's orbital period?

Orbit altitude (semi-major axis) Spacecraft color Rocket height Payload mass only

18. Which orbit passes over both poles?

Equatorial Orbit Polar Orbit Geostationary Orbit Transfer Orbit

19. What does an eccentricity of 0.5 indicate?

Circular orbit Elliptical orbit Hyperbolic trajectory Straight line

20. Which launch direction gives the greatest velocity boost?

North South East West

21. Low Earth Orbit is approximately...

160–2,000 km 10,000 km 35,786 km 400,000 km

22. Which maneuver changes orbital inclination?

Plane Change Circularization Burn Retro Burn Gravity Turn

23. Which orbit keeps a satellite above the same point on Earth's equator?

Polar Molniya Geostationary Elliptical

24. A launch window is...

Rocket hatch Time when mission objectives can be achieved efficiently Space station window Navigation display

25. Which law states every action has an equal and opposite reaction?

Newton's First Law Newton's Second Law Newton's Third Law Kepler's Third Law

26. What is staging used for?

Increase payload mass by discarding empty tanks Make rockets louder Increase drag Slow the rocket

27. Which mission first landed humans on the Moon?

Apollo 8 Apollo 11 Gemini 4 Artemis I

28. Which planet requires the least delta-v from Earth to reach during favorable transfer windows?

Mercury Venus Jupiter Neptune

29. Which quantity is usually measured in meters per second (m/s)?

Inclination Delta-v Eccentricity Orbital Period

30. Mission Control says, "Go for TLI." What does TLI stand for?

Terminal Launch Inspection Trans-Lunar Injection Total Lift Initiation Thrust Limit Indicator