CryoSat Failure Analysed - KOMPSAT-2 Launch in Spring 2006 Bremen, Germany, December 21, 2005 The root cause of the CryoSat failure on October 8, 2005 has been unambiguously identified and corrective measures for Rockot`s return-to-flight are now under way for the safe launch of Kompsat-2 in the second quarter of 2006, as agreed between the Korea Aerospace Research Institute and Eurockot Launch Services. Human error and not an inherent design flaw of the launch vehicle caused the failure. On October 8, 2005 the launch of ESA's CryoSat satellite on board a Rockot launch vehicle had ended in failure. Due to an anomaly towards the end of the planned 2nd stage operations and approximately five minutes after lift-off, the launch vehicle had automatically terminated its mission. The combined stack of the launch vehicle (2nd, 3rd stage) and the CryoSat spacecraft had impacted into the Arctic Ocean. A Russian State Commission including members from Khrunichev (the Launch Vehicle contractor), Khartron (the Control System subcontractor), the Russian Federal Space Agency, Space Forces as well as Russian industrial representatives was convened immediately after the mishap. Its investigation work has been concluded by issuing a commission report including recommendations. A summary of the findings of the Russian State Commission final report was presented to Eurockot and ESA on November 3, 2005 in Moscow. In parallel to the Russian State Commission investigation, a Eurockot Failure Review Board was formed to review the Russian State Commission investigation results as well as its conclusions and recommendations. This resulted in an independent report, drawing its own conclusions and recommendations. The board was co-chaired by Eurockot and Khrunichev senior managers and comprised of experts from Eurockot, Khrunichev and EADS Space Transportation. The European Space Agency (ESA), to whom the CryoSat satellite belongs, participated within the Eurockot Board as observers. The launch failure was ultimately caused by the 2nd stage main engine not being shut down at the correct time, leading to an engine burn until the propellants were depleted. Due to this incorrect shut down, an engine failure occurred resulting in a lateral force on the launch vehicle. This resulted in unstable flight causing the vehicle flight angles to exceed allowable limits. In accordance with the flight programme, the on-board computer automatically terminated the mission at 308s into the flight. As a consequence, the 2nd stage was not separated from the 3rd stage and the 3rd stage main engine was not ignited. The whole stack of 2nd stage, 3rd stage and CryoSat spacecraft dropped within the nominal drop area of the second stage. Analysis of the telemetry data indicates that the 1st stage performed nominally. The 2nd stage performed nominally until main engine shut down was to occur. Telemetry records show that the command to shut down the 2nd stage main engine by the on-board computer was generated correctly. However for this shut down command to be carried out, a further condition must be met. This requires that the pressurisation of the low pressure tank of the 3rd stage Breeze be fully completed before the shut down command can be carried out. Due to human error, the completion time of the pressurisation sequence for the CryoSat launch was erroneously specified and occurred after the shut down command was generated and therefore it was not carried out. In nominal mission cases, this 3rd stage pressurisation is completed well before the 2nd stage main engine shut down command is generated. This error had also not been identified by existing verification and testing procedures. The Eurockot Review Board concurs fully with the Russian State Commission's findings of the root cause. Furthermore the Eurockot Review Board fully agrees with the Russian State Commission's proposed return-to-flight measures. In summary, four aspects will be improved and implemented for return-to-flight.  Firstly, the pressurisation timeline will in the future be constrained within a fixed window within the overall mission timeline. Improved and more thorough verification procedures will be introduced when generating the mission timeline input data both at Khrunichev and the control system subcontractor Khartron. Additionally improved testing during 'electronic launch' simulation at the Control System subcontractor shall be introduced. Finally, the Eurockot Review Board has recommended that further measures be undertaken to provide improved visibility of mission peculiar aspects of future missions. The Eurockot Review Board will monitor that these return-to-flight measures and their resulting action items have been correctly implemented in a series of project meetings and reviews prior to the next launch of Rockot, which is for the Kompsat-2 spacecraft in 2Q 2006. Furthermore, the Russian State Commission, as part of the Flight and Launch Readiness Reviews for the Kompsat-2 launch, will formally provide the go-ahead for launch. The Kompsat-2 launch will be followed by the ESA missions GOCE, SMOS and Proba-2 in 2007, in which year Eurockot will also launch an earth observation satellite for an undisclosed customer.

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