Increasing the utilization of the ISS Mobile Servicing System through ground control

On February 24th, 2005 the Mobile Servicing System (MSS) was maneuvred on the International Space Station (ISS) by an operator from the ground for the first time, marking a first in human space flight history. Allowing ground support teams the capability to move the MSS in a manner that satisfies human space flight safety requirements provides an invaluable tool in supporting more efficient utilization of both the MSS and the ISS. Ground control allows for the optimal separation of on-orbit crew and ground functions; thereby redirecting more on-orbit crew time towards other more scientifically rewarding ISS utilization activities.Apart from supporting routine ISS operations, significant benefits will also be gained from ground control to support engineering investigations. One of the “way-of-doing-business” adjustments that was required for the MSS on the ISS over the original robotic manipulator system developed for the Space Shuttle (the “SRMS”), was in the sustaining engineering support function. Many SRMS minor on-orbit anomalies are investigated in detail after the mission is completed and the arm has returned to earth. In the case of the MSS where it remains on-orbit, engineering investigations and performance characterization efforts are more challenging. However, contrary to initial expectations, the challenge in troubleshooting and characterizing the MSS was not because of lack of data or insight into the on-orbit system, but rather due to lack of on-orbit crew time for engineering investigations. This has led to some engineering support teams having to wait up to a year before even straightforward troubleshooting investigations could be scheduled and executed. Ground control affords a more efficient way of characterizing and maintaining the health of the MSS.This paper will describe the utilization challenges the MSS has faced in the past, provide an overview of the MSS ground control capability, and discuss the benefits that are expected to be gained through the implementation of a ground control capability.