Eeloo I is our first spacecraft designed to travel beyond the orbit of Duna. That far out, solar power is no longer a practical form of power due to the sun's dimishing light. Rather than attaching gargantuan solar arrays onto the craft (which are a nightmare in terms of reliability) the use of atomic generators is preferred. However, the R&D lab at the KSA has been unable to create one small enough for practical use as a probe. Because it's important that we take advantage of this window to get to Eeloo as it swings close to the sun, we've built a probe around a large thermo-electric rover body. This has meant we've needed to construct our largest rocket to date to carry it into orbit and on to Eeloo.
After a close review of the ascent data, video and records held in misson control computers, it has been determined that the rocket, as designed, was not capable of reaching orbit. It appears we grossly underestimated the role our new 3-segment booster rockets would play in the initial ascent phase - they carried a lot more of the thrust than anticipated and once they were cut loose our TWR dropped below 0.80, which is not sufficient enough to maintain acceleration to orbit. Although we did eventually climb high enough and burn enough fuel to reach an acceptable level of TWR, by then our trajectory had flattened out and required near-full deflection of control surfaces to keep the rocket pointing skywards. Once the lift stage was jettisoned and we lost the control surfaces the rocket went into an unrecoverable tumble and the self-destruct command was sent before signal loss over the horizon.
