Kerbal 5 / Supporter 1: Circling the Mun... with a few problems

[AndrewBCrisp]

Preamble

With the recent successful completion of the KerbalLab 1 mission, proving Kerbals can stay in space for extended periods without getting (too) bored or running out of snacks, the Kerbal Space Program decided that now was the time to attempt a Kerballed mission to the Mun. A first attempt was made with Kerbal 4, but not 3 minutes into the launch, a malfunction caused the Service Module engine to fire while the core stage was still boosting. Thankfully, the new emergency abort systems worked flawlessly, and the Kerbal 4 crew (Henfred Kerman, Geofvey Kerman, and Corbo Kerman) escaped with no injuries. The same could not be said for their underwear.

After tracing the flaw to improper wiring and stage-control programming, KSC decided to try again. Kerbal 5 was prepared with a new crew. Bill Kerman was selected as Commander, with Dilfel Kerman as pilot and astronomer Sigdorf Kerman as mission specialist. This would be Bill's second space mission.

Reaching the Mun

Kerbal 5 launched on Day 180, and achieved orbit with none of the problems that plagued Kerbal 4.

Liftoff!

Kerbal 5 separating from the KerbalLifter-III core stage.

Despite suggestions from some scientists that Kerbal 5 should employ something called a "free return" trajectory, KSC mission planners opted for a more direct approach. Kerbal 5 took a little over 5 hours to reach the Mun once it completed its trans-Munar injection burn, and entered into a prograde orbit. Here the first real concern manifested itself when Dilfel reported the spacecraft's fuel consumption. As a result, plans to place Kerbal 5 in a 100 km circular orbit, inclined for maximum coverage of the Mun's surface were scrapped, and the spacecraft settled into an elliptical orbit with a 350 km apoapsis and a 150 km periapsis.

Kerbal 5 conducting its Munar orbital insertion burn.

Nevertheless, the views of the Mun were superb.

Sigdorf: "So many craters... They should have sent a poet."

After a few orbits, Kerbal 5 made the return trip. However, while conducting the burn to place the spacecraft into Kerbin orbit, Dilfel's worst fears were confirmed - the spacecraft exhausted its fuel supply before it could complete the burn. Kerbal 5 was trapped in an elliptical orbit, 194 km Pe / 445 km Ap, with no way to return home.

Fortunately for the crew of Kerbal 5, help was a lot closer than they could have dreamed.

Supporter 1 under construction in the VAB.

The next scheduled mission to KerbalLab would have involved a mid-mission resupply of the space station by a robot supply ship. This vessel, Supporter 1, had just cleared its ground checks when Kerbal 5 was stranded in orbit. As Supporter 1 was designed to carry 4 tons of fuel, and another 4 tons of RCS monopropellant, Flight directer Gene Kerman ordered the supply ship to be launched at once.

Supporter 1 approaches the stranded Kerbal 5

Saved!

"The supply ship took close to 4 hours to rendezvous with us, and docking was nearly flawless," Bill Kerman reported shortly after Supporter 1 began to transfer its vital cargo. "Nobody tell Jebidiah that a robot beat his docking record."

It's job complete, Supporter 1 burns up in Kerbin's atmosphere.

With a fresh supply of fuel, Dilfel was able to circularize the spacecraft's orbit, and even attempted to bring the capsule down near KSC. No previous returning spacecraft was able to accomplish this, and Dilfel sadly wasn't able to change that. Kerbal 5 splashed down safely in the ocean over a hundred kilometers west of KSC, and was recovered with no further incidents.

Kerbal 5's triumphant return.

Aftermath and Lessons Learned

Supporter 1's excellent performance helped save the lives of three Kerbals, and demonstrated the utility of robot supply ships to aid Kerbal exploration of space. However, the rescue has pushed back the KerbalLab 2 mission, as a new Supporter spacecraft must be built and ready before the mission can be attempted.

As for future missions to the Mun, the fuel issue has forced KSC mission planners to rethink their approach. Among the options being considered to solve the problem are:

• Employing a Munar Transfer stage for the trans-Munar injection burn, thus saving fuel for the return trip,
  
• Employing Supporter spacecraft for refuelling, either in Kerbin orbit on return, or even in Munar orbit,
  
• Employing the til-now neglected Free Return trajectory for future missions.
  
• 
  

Gene Kerman has stated that future Kerbal missions will take a "belt and suspenders" approach to safety, suggesting that possibly all of these options will be used.