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Their one-way delta-v budgets from LEO range upwards from 3.8 km/s (12,000 ft/s), which is less than 2/3 of the delta-v needed to reach the Moon's surface. [10] But NEOs with low delta-v budgets have long synodic periods , and the intervals between times of closest approach to the Earth (and thus most efficient missions) can be decades long.
By examining the results of the porkchop plot, engineers can determine when a launch opportunity exists (a 'launch window') that is compatible with the capabilities of a particular spacecraft. [2] A given contour, called a porkchop curve , represents constant C 3 , and the center of the porkchop the optimal minimum C 3 .
Thus it can be shown that, provided the exhaust velocity is fixed, this means that delta-v can be summed: When m 1, m 2 are the mass ratios of the maneuvers, and v 1, v 2 are the delta-v of the first and second maneuvers = / / = + = / = where V = v 1 + v 2 and M = m 1 m 2. This is just the rocket equation applied to the sum of the two maneuvers.
Going from one circular orbit to another by gradually changing the radius simply requires the same delta-v as the difference between the two speeds. [14] Such maneuver requires more delta-v than a 2-burn Hohmann transfer maneuver, but does so with continuous low thrust rather than the short applications of high thrust.
Belbruno's routes from low Earth orbit require a 3.1 km/s burn for trans lunar injection, a delta-v saving of not more than 0.4 km/s. However, the latter require no large delta- v change after leaving low Earth orbit, which may have operational benefits if using an upper stage with limited restart or in-orbit endurance capability, which would ...
For more complicated maneuvers which may involve a combination of change in inclination and orbital radius, the delta-v is the vector difference between the velocity vectors of the initial orbit and the desired orbit at the transfer point. These types of combined maneuvers are commonplace, as it is more efficient to perform multiple orbital ...
[2] Importance of Structural coefficient and I SP for Single-Stage-to-Orbit (SSTO) and restricted stage Two-Stage-to-Orbit (TSTO) vehicles. Based on a LEO mission of Delta v = 9.1 km/s and payload mass = 4500 kg for range of propellant Isp. GLOW=Gross Lift-Off Weight
It is a highly elliptical orbit with an inclination of 63.4 degrees, an argument of perigee of 270 degrees, and an orbital period of approximately half a sidereal day. [1] The name comes from the Molniya satellites, a series of Soviet/Russian civilian and military communications satellites which have used this type of orbit since the mid-1960s.