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⇤ ← Revision 1 as of 2018-02-08 02:12:06
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Size: 2652
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| Launch loops are not limited by the Tsiolkovsky exponential; while high loop velocities require large radius ambit magnets and vertical deflection magnets, the difference between an 8 km/s launch and an 11 km/s launch is doubled energy cost (electrical power, not cryofuel), but not an exponentially larger loop. | Launch loops are not limited by the Tsiolkovsky exponential; while high loop velocities require large radius ambit magnets and vertical deflection magnets, the difference between an 8 km/s launch and an 11 km/s launch is doubled energy cost (electrical power, not cryofuel), but not an exponentially larger loop. |
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| || || km ||<-2> m/s || | || || km ||<-2> m/s || |
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| So, no additional delta V added for direct upward vehicles. about 28 m/s delta V added at L1 apogee for indirect-via-L1 vehicles. | So, no additional delta V added for direct upward vehicles. about 28 m/s delta V added at L1 apogee for indirect-via-L1 vehicles. |
Ultra High Apogee Orbits
Launch loops are not limited by the Tsiolkovsky exponential; while high loop velocities require large radius ambit magnets and vertical deflection magnets, the difference between an 8 km/s launch and an 11 km/s launch is doubled energy cost (electrical power, not cryofuel), but not an exponentially larger loop.
From 100 km altitude (6478 km radius, ignoring residual atmospheric drag and J₂ oblateness), the launch and insertion velocities to various apogees are:
|
km |
m/s |
|
|
apogee |
launch |
insert |
400 km LEO |
6778 |
7460 |
87 |
server sky |
12789 |
8566 |
1005 |
GEO |
42164 |
9856 |
1488 |
Moon |
384400 |
10529 |
833 |
Earth-Sun Lagrange 1 |
1500000 |
10597 |
251 |
transfer to GEO via L1 parking orbit |
|||
L1/10,000 km parking |
1500000 |
28 |
1294 |
Imagine a rotating tapered tether at GEO, which can capture vehicles launched directly from Earth (adding delta V and angular momentum to the arriving vehicle) or from an L1/GEO transfer orbit (subtracting delta V and angular momentum from an arriving vehicle). If the ratio of the mass streams is 1294 to 1488 (15% more vehicle mass arriving via an L1 apogee), then no makeup momentum or thrust needs to be added at GEO. THis assumes elliptical equatorial-plane orbits that "kiss" GEO; with additional radial velocity, we may be able to balance rotating tether angular momentum at GEO as well (this needs further study).
So, no additional delta V added for direct upward vehicles. about 28 m/s delta V added at L1 apogee for indirect-via-L1 vehicles.
L1 "orbit" is about 300 m/s sidereal relative to the Earth, faster than an isolated orbit without the Sun's gravitational influence. Vehicles in Earth orbit with perigees at that radius will return to Earth, though solar and lunar gravitational perturbations will be significant. The actual orbit and delta V must be computed and adjusted for every individual mission. On the other hand, we can probably manage the object cloud to minimize collisions and maximize launch rates throughout the day, month, and year. Some of the vehicles will make many orbits before arriving at GEO; these will be unmanned cheap cargo orbits. Given that payloads today sometimes wait years for orbital slots, launching them into orbit cheaply for eventual delivery (perhaps months later) may be a cost-effective tradeoff - better late than never!