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|| ||<-3:> Earth + 80km to: ||
|| || GEO || Luna || L1 ||
|| perigee || 6458 || 6458 || 6458 || km ||
|| apogee || 42164 || 382662 || 326390 || km ||
|| Vperigee || 10.346 || 11.018 || 11.002 || km/s ||
|| Vapogee  || 1.585 || 0.186 || 0.218 || km/s ||
|| ΔV launch || 9.881 || 10.553 || 10.537 || km/s ||
|| Varrive || 1.490 || 0.832 || 0.647 || km/s ||
|| ΔV landing || 1.490 || 2.521 || 0.647 || km/s ||
||'''total ΔV'''|| 11.371 || 13.074 || 11.184 || km/s ||
||   ||<-3:> Earth + 80km to: ||
||   || GEO  || Luna || L1 ||
|| perigee       || 6458 || 6458 || 6458 || km ||
|| apogee        || 42164 || 382662 || 326390 || km ||
|| Vperigee      || 10.346 || 11.018 || 11.002 || km/s ||
|| Vapogee       || 1.585 || 0.186 || 0.218 || km/s ||
|| ΔV launch  || 9.881 || 10.553 || 10.537 || km/s ||
|| Varrive  || 1.490 || 0.832 || 0.647 || km/s ||
|| ΔV landing  || 1.490 || 2.521 || 0.647 || km/s ||
||'''total ΔV''' || 11.371 || 13.074 || 11.184 || km/s ||
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The travel time to a direct Lunar landing is 5 days, while the travel time to L1 is one day less. That means less cryo-propellant boiloff during the journey.

L1 requires the least total ΔV. "Landing" (= apogee insertion) is by far the lowest for L1, a quarter of the lunar landing delta V. While the launch ΔV to L1 is higher than launch to GEO, a launch loop produces launch delta V very cheaply.

Lunar Base Power from L1 SSPS

L1SSPS

Baseline: Power a lunar base with a surface power plant

Delivering a power plant to Luna's surface requires a high speed launch into a Hohmann to Luna, plus extra velocity to match Luna's 1.022 km/s (average) orbit velocity, plus lunar escape velocity, 2.38 km/s .

Luna's semimajor axis is 384,400 km - let's use that for the "average" radius. Luna's equatorial radius is 1738 km, so a direct Hohmann to the nearside surface has an apogee of 384,400 - 1738 = 382,662 km .

Lunar L1 is 326,390 km from Earth's center.

We can calculate total delta V, launching from the launch loop:

Earth + 80km to:

GEO

Luna

L1

perigee

6458

6458

6458

km

apogee

42164

382662

326390

km

Vperigee

10.346

11.018

11.002

km/s

Vapogee

1.585

0.186

0.218

km/s

ΔV launch

9.881

10.553

10.537

km/s

Varrive

1.490

0.832

0.647

km/s

ΔV landing

1.490

2.521

0.647

km/s

total ΔV

11.371

13.074

11.184

km/s

trip time

5.24

118.62

93.84

hours

The travel time to a direct Lunar landing is 5 days, while the travel time to L1 is one day less. That means less cryo-propellant boiloff during the journey.

L1 requires the least total ΔV. "Landing" (= apogee insertion) is by far the lowest for L1, a quarter of the lunar landing delta V. While the launch ΔV to L1 is higher than launch to GEO, a launch loop produces launch delta V very cheaply.

L1SSPS (last edited 2021-04-08 01:43:46 by KeithLofstrom)