Moho Exploration

[Hannu]

I started a new game (0.22) and thought that this time I make relatively simple manned explorations to all planets and no permanent bases or stations. I start from Moho and try to make some kind of report about the mission. English is not my own language, so I hope that you forgive errors or strange style things in the language. Or teach me how things should be written.

I assume a historical situation, in which kerbals have much experience in operations in Kerbin's system and some experience in interplanetary travels. Now they have great global space boom and the government gives the huge funding to manned exploration of the whole Kerbol's planetary system.

I will use following mods:

Mechjeb 2

SCANsat

EnhancedNavball

KAS

KerbalAlarmClock

CrewManifest

DockingPortAlignment

I will use also alexmoon's launch window calculator to draw porkchop plots. I assume that it is OK to use screenshots from it, but if it is against some copyright rules, I will take them away and use my own software (which is not ready yet).

I use time notation 01 067 which means year 1 day 67 in game's UT.

Part 1: Mission plan and Moho Scansat 1

Mission plan

First Moho mission Moho 1 (sorry about boring names) begins with unmanned orbiter which maps the planet. Then a rover and a lander will be sent with separate launches. All spacecrafts have transfer stages which have extra fuel reserves and they will act as a tugs and/or fuel stations during later operations around the planet.

When the planet has been mapped and the lander and the rover are on their orbits, three man crew will be sent with Moho 1 during a low energy launch window around day 01 341. They will maneuver their craft on inclined 80 km circular orbit and rendezvous with the lander. After that they make the first landing to some interesting place depending on the results of topographic scanning. Mission should have resources for several landings.

Return trip is planned to begin at launch window near day 02 057.

Moho Scansat

Moho Scansat will map the whole surface topographically. Landing places will be selected after mapping. The KSC chooses the launch window at 01 067. It has dv

requirement 4908 m/s (from 300 km orbit to 100 km orbit). Ejection dv is relatively low, 1454 m/s and insertion dv high 3454 m/s.

Porkchop plot of 01 067 launch window (given by alexmoon's calculator)

Scansat is 0.5 t satellite which uses SCANsat mod. The mass of transfer stage is about 40 t and it has dv capability of about 12000 m/s. It is far more than the

ScanSat needs but the stage serves as a tug and fuel station during manned phase of mission. Stage has 5 LV-N:s during TMI burn and after that 4 boosters will be jettisoned.

This transfer does not need large inclination change. Just about 25 m/s. Therefore I start from 200 km zero inclination orbit. Launch mass is 407 t. Launcher is very rigid and stable. Launch and ascend goes nominally under MechJeb2's control.

01 055 Launching vehicle in VAB.

01 055 First minute goes flawless.

01 055 First staging.

01 055 200 km orbit inclination 0.0 deg.

Moho's SOI is so small that it is difficult to get encounter in orbit calculator mode. Fortunately MechJeb's Maneuver Node Editor gives very accurate adjustments. 1 s or 1 m/s change lose the encounter. For some reason Alexmoon's calculator gives slightly greater (10-20 m/s) dv values than is actually needed, although I take Kerbin's limited gravity range into account (it gives energy which correspond to 290 m/s).

Trans Moho injection goes nominally. Moho Scansat needs two small corrections before Moho's SOI, totally about 23 m/s.

01 067 Trans Moho injection takes 1470 m/s.

01 070 Fuel is pumped to the large tank and two engines are jettisoned.

01 102 Finally in Moho's SOI.

This geometry needs large orbit insertion burn, about 3200 m/s. The craft is on very eccentric orbit after MOI. Scansat is separated from transfer stage. Transfer stage is left 100 km x 8250 km inc 32.1 deg orbit to wait future needs. Scansat changes plane to nearly polar and starts to map Moho's surface from 517 x 520 km orbit.Power consumption of the scanning device is quite high causing lack of electricity when the satellite is in Moho's shadow. Therefore it leaves small hole in the map. But it can be fixed when other crafts are on transfer orbits.

01 102 3225 m/s MOI burn takes nearly 8 minutes.

01 105 Moho Scansat is ready to topographic mapping.

01 112 After a week we have nearly complete map.

[turbo917k]

What a nice report, great work.

T