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Sketch of a circumlunar free return trajectory (not to scale), plotted on the rotating reference frame rotating with the moon. (Moon's motion only shown for clarity) In orbital mechanics, a free-return trajectory is a trajectory of a spacecraft traveling away from a primary body (for example, the Earth) where gravity due to a secondary body (for example, the Moon) causes the spacecraft to ...
The five species model is only usable for entry from low Earth orbit where entry velocity is approximately 7.8 km/s (28,000 km/h; 17,000 mph). For lunar return entry of 11 km/s, [23] the shock layer contains a significant amount of ionized nitrogen and oxygen. The five-species model is no longer accurate and a twelve-species model must be used ...
A space vehicle's flight is determined by application of Newton's second law of motion: =, where F is the vector sum of all forces exerted on the vehicle, m is its current mass, and a is the acceleration vector, the instantaneous rate of change of velocity (v), which in turn is the instantaneous rate of change of displacement.
The concept has also been used to extend the reentry time for vehicles returning to Earth from the Moon, which would otherwise have to shed a large amount of velocity in a short time and thereby suffer very high heating rates. The Apollo Command Module also used what is essentially a skip re-entry, as did the Soviet Zond and Chinese Chang'e 5-T1.
A velocity map shows the speed and direction that material at the sun's surface is moving. Blue shows movement toward the Solar Orbiter, while red indicates movement away from the spacecraft.
Watch live as a Nasa spacecraft returns to Earth with the largest asteroid sample in history on Sunday 24 September. After a seven-year, four-billion-mile journey across space, the ambitious NASA ...
The delta-v required to return from Near-Earth objects is usually quite small, sometimes as low as 60 m/s (200 ft/s), with aerocapture using Earth's atmosphere. [10] However, heat shields are required for this, which add mass and constrain spacecraft geometry. The orbital phasing can be problematic; once rendezvous has been achieved, low delta ...
The Boeing Starliner spacecraft is now scheduled to undock from the International Space Station and return to Earth on June 22, NASA said on Friday, giving more time to finalize planning for the ...