Operation Crispy Rock (manned mission to Moho)

[Bekiekutmoar]

The KSC has designed an interesting ship for trips to and from the innermost planet Moho. This vessel relies for a significant part on two Ion Engines with a total thrust of a whopping 1 Kn, but with an extremely economical ISP of 4200. Thus, the size of the interplanetary ship can be kept limited as there is much less mass to move around. The initial mass of the ship is 44-45 tons, but when the Ion Engines will be activated, the mass will most likely have dropped below 5 tons ... ! There will be 4 crewmembers; Jeb, Bob, Dohat and Kircas. They'll stay in a Hitchhiker Container while the vessel will be controlled with a probe core. All to keep the mass low ... !

Mission planning; the Kerbonauts will travel to Moho and get into orbit with a nuclear engine. The KSC claims the asparagus-staged group of fuel tanks on the hind section of the ship will be sufficient to perform these actions. A small probe at the front will be released shortly before entering the SOI of Moho. After that, a small lander with one Kerbonaut will land on the surface, then return to the mothership. The Kerbonaut will be transferred back to the Hitchhiker Container, the Lander ditched, and the then low-mass vessel will return to Kerbin solely on Ion Engines.

Below the already assembled ship in LKO. Unmanned though at the moment, the Kerbonauts are to be transferred shortly ... !

[Rhyunix]

Nice design, I would be interested to see if you created a way to leave the Hab module in a Moho orbit for further missions- You have my interest

Edited February 9, 2014 by Rhyunix

[Bekiekutmoar]

Well, Eve is probably out of the scope at the moment, unless I've got fuel to spare after the gruesome retroburn for orbital insertion around Moho. Speaking about Moho, it turns out I've got a launch-window to the planet right now ... ! Bill Kerman has been assigned as pilot to ferry the four crewmen to the Crispy Rock. That's right, the ship carries the same name as the mission itself ... !

The experienced Bill manages to carry out two well-pointed flights to the Crispy Rock in just one night. Now that's effectiveness ... !

Day 1: Jebediah, Bob, Dohat and Kircas depart to Moho, leaving the partly clouded Kerbin behind. Due to the fairly low TWR, it takes three passes to reach escape velocity. All crewmembers are in good spirit and rather enthousiastic about the mission.

[Brotoro]

Good luck! Moho can be a real mofo at times.

[Scotius]

I'm afraid your crew enthusiasm will disappear when they realise how long returning burn will take Hope you have MechJeb onboard - or weekend reserved

[Bekiekutmoar]

Well, this mission went down the drain quickly. The Crispy Rock had lots of fuel left when orbital corrections for an encounter of Moho were completed, but it wasn't enough to burn away the velocity of 7,4 km/s relative to Moho. At day 22, the front probe was released and made a Moho flyby at just 15 km from the surface.

The Crispy Rock entered the SOI of Moho on day 25 with an initial relative velocity of 7,4 km/s and immediately began retroburn. Within 20-25 minutes, the ship passed at just around 9 km above the barren landscape and with velocity dropped to 5,3 km/s. At 2,2 km/s, 'normal' fuel was depleted and the Ion Engines were activated, but it quickly became clear orbital insertion around Moho would never be achieved and shooting off into interplanetary space was unavoidable. The unfortunate crew now faces years and years of circling around Kerbol with little chance of them beiing rescued, although there may be a way to improve their awful situation; although the Crispy Rock now lacks the Delta-V to reach Kerbin, Eve might still be a possibility. Proper aerobraking in the Evian atmosphere might result in an orbit around the purple planet, making a rescue mission in the near future a whole lot easier. But can Eve be reached anyway with the remains of the ship ... ?

Desperate retroburn ...

Ejecting the last empty fuel-tank

[Scotius]

Oh yeah, Moho can be a real b***. You have to either be extremely cautious with planning the trip, or pack a small sea of fuel. Or both I don't feel safe without a ship capable of carrying close to 9 km\s dV - preferably more.

[Tangle]

So- I've done a single Moho mission, and it just barely managed to do it. It was a probe version replica of Brotoro's Mark Twain orbiter/lander. The Orbiter managed to make it into an orbit with a tiny bit of fuel left, and the two landers were taken to the surface. All in all, the mission went succesfully. However, that was in 0.20. Now, I have a better computer, more mods, and a 55 ton lifter craft that I can put on another lifter to get lots of delta-V(11 KM/S!).

[Bekiekutmoar]

In the meanwhile, the four crewmen have managed to improve their chances of ever returning to Kerbin, but only with extreme and desperate effort. A summary:

Jebediah, Bob, Dohat and Kircas agreed they had to reach Eve and aerobrake in the atmosphere to establish orbit around the planet, making a rescue mission in the (near) future easier. It became clear they had to burn on day 35 of the mission (at PE around the Sun) to reach Eve with the least Delta-V; around 2200 m/s. The lander was transformed into some form of propulsion module.

Day 35: the transfer burn occured with all regular fuel and RCS depleted after mere minutes and all Xenongas after one hour. Around 50 m/s was 'left' of the transfer burn when all propellants were used and the ship essentially became dead weight … All was lost … Or not … ?

Not all was lost … ! The crew refused to give up and decided to get out and push the ship onto the right trajectory with their EVA-packs.

Day 78: the ship entered Evian SOI with a relative speed of over 7 km/s and the crew decided to put the PE at 54 km. Getting too low into the atmosphere would mean certain death, aerobraking too high would mean shooting off again into interplanetary space. It was all or nothing … !

The tense crew during the dangerous aerobraking …

But this aerobrake turned out to be just right; it resulted in an orbit with AP at around 1100 km and PE around 50 km. The Kerbonauts got out and pushed their spacecraft again at Apoapsis to raise the PE to at least 100 km. Now the ship is relative safe around Eve and the waiting for a rescue mission has begun … !

[Scotius]

Good job And you won't even have to send a ship with crew module. Just a probe controlled tug to dock with Hitchhiker, and tow it back to Kerbin.

[Brotoro]

Rescue time! I had to rescue the first crew I sent to Moho as well.

[Geschosskopf]

A daring mission to undertake and deeds of derring-do to salvage something from it. Well done!

[Bekiekutmoar]

Back on Kerbin, the KSC has launched the 'Ramelia Combination', containing a simple unmanned tug and a cheap probe that'll eventually be dropped on the Evian surface. The combination is currently in LKO and awaiting a transfer-window to Eve. Main task of this vessel is to retrieve the stranded ship with Jeb, Bob, Dohat and Kircas around Eve.

In all the chaos, the KSC has almost forgotten about a part of the Crispy Rock-mission that actually functions very well; the probe that was released from the manned vessel on day 22 of the mission … ! After the Moho-flyby, it entered Solar orbit with PE at around 3,5 million km and AP at 13 million km. After the violent but succesful orbital insertion around Eve of the Crispy Rock spacecraft and the 4 crewmembers, the KSC focused on the lonely probe and decided to direct it to Duna. On day 92, the probe reached the PE again and then activated its Ion Engine to alter the trajectory towards Duna, requiring roughly 1 km/s of Delta-V. Due to the low mass of the probe (0.4 tons), the 'burn' was completed in 14 minutes.

Day 125: the probe entered the SOI of Duna with a relative speed of circa 3,5 km/s. The KSC decided to put the PE at 8 km and the probe made a spectacular entry in the atmosphere above the northern polar region.

Just like the 'last-ditch-effort' aerobrake of the Crispy Rock in the Evian atmosphere, this crazy aerobrake in the Dunian atmosphere turned out to be a good guess and resulted in an orbit with AP at 254 km and EP at 4 km. Circulization occured shortly after this … !

Edited February 6, 2014 by Bekiekutmoar

[Scotius]

Well done. Looks like you can salvage more of this "failed" mission than we would guess at first look.

[kiwiak]

Such "failed" missions are intersting unes.. (unless its complete failure and nothing can be done).. loking forward to next part.

Edited February 8, 2014 by kiwiak

[Bekiekutmoar]

Well, its a successful failure so far …

Small update this time: at day 138 of the original mission, the Ramelia Combination began a Hohmann-burn towards Eve. The total mass of the vessel wasn't that huge so escape velocity was relative quickly achieved.

After some orbital corrections, the probe on the front of the vessel was released. While the main purpose of the Ramelia Combination is to rescue the 'dead' Crispy Rock in Evian orbit, the probe was designed to take a look at the Evian surface.

Its day 193 of the original mission, and 55 days after launch, the probe reaches the purple planet several hours ahead of the unmanned tug. The landscape beneath the thick clouds would soon be revealed.

The probe makes a fiery entry in the atmosphere, and descends slowly into the purple soup afterwarts. However, the unforgiving gravity prooves too much for the unfortunate machine.

But … the most important part of the rescue-vessel manages to get into a very eccentric orbit around Eve. Massive orbital corrections will be required with probably a lot of aerobraking and burning several hundreds of Delta-V to match the orbit of the Crispy Rock, but fuel-shortage probably won't be an issue as the economical nuclear engine has no problem moving the not-too-massive module around.

[Rhyunix]

An unfortunate robotic landing, but the rescue is still a go!

[Bekiekutmoar]

Day 198: the unmanned tug 'Ramelia' has managed to reach the Crispy Rock. The crewmembers were delighted ... ! The unmanned vessel had to use a considerable amount of fuel to make some major course-corrections, but a bit over 50% of fuel is left. The new combination has a total mass of around 18 tons, so reaching Kerbin probably won't form a problem. However, the next suitable launch-window is months and months away ... !

[Geschosskopf]

Pity the probe splattered. But good job on linking the rescue tug up with the stranded Kerbals. Stranded craft have this habit of getting into really inconvenient orbits to rendezvous with, as I've found out several times.

[Bekiekutmoar]

Thanks for the Rep ... ! When returning to Kerbin, I really shouldn't get somewhat careless as the vessel doens't have any parachutes and falling to death on the home planet would be a bit laughable after such a journey through the inner Solar System ...

[astropapi1]

Very nice thinking there, Bekiekutmoar. I'm glad you're getting your guys back to Kerbin.

[Bekiekutmoar]

After being in orbit around Eve for 230 days, the Crispy Rock and its crew began burning for a Hohmann-transfer back to Kerbin on day 308 of the mission. It took two passes to reach escape velocity.

It appeared the timing of the interplanetary transfer was a bit off and a massive mid-course correction of 1400-1450 m/s was needed to eventually encounter Kerbin … ! However, due to the mass of the vessel being shrunk to around a mere 13 tons at this time, this correction was relative quickly done with still enough fuel left after the burn.

Day 345 … Celebration in the Hitchhiker Module, because the ship entered the SOI of Kerbin … ! Relative speed was around 1550 m/s at 80.000 km from Kerbin, and increased to roughly 3600 m/s just above the atmosphere. The crew decided to put the PE at 40 km.

Despite the PE being at 40 km, some additional retroburning was needed to avoid drifting into interplanetary space again. It took a significant amount of time to establish a stable LKO (100 km) with proper aerobraking and some retroburn, but at day 355, the crew signaled the KSC that they were ready for extraction. Two flights will be required to get Jeb, Bob, Dohat and Kircas down to the surface.

[Bekiekutmoar]

OK, time for the final update: two flights were scheduled to retrieve the four Kerbonauts from the Crispy Rock. Bill Kerman flew the first rocket and reached the target vessel within 45 minutes, and landed on the surface again with Dohat and Kircas one hour after launch. The newbie Desden Kerman piloted the second rocket, retrieved Jebediah and Bob, and also landed within one hour.

Even the space-hungry Jebediah was pleased to see the mostly green hills and blue sky of Kerbin again after flying 355 days through the vastness of space.

And the mission ended … ! Altough the Kerbonauts never set foot on Moho -as was intented- the KSC considered the mission still mostly as a success because the crewmembers had escaped a gruesome fate and were rescued, and ofcourse the probe that still functions well in a polar orbit around Duna.

Dohat and Kircas highlighted by Bill:

Jeb and Bob highlighted by Desden:

Thanks for watching … !

[Scotius]

Congratulations on a succesful rescue mission. Well done

[Geschosskopf]

Glad everybody got home