The Impact Of Station Program Notes On The ISS Robotics Systems Group

Paper number

IAC-07-B3.I.05

Author

Ms. Laura Lucier, Canadian Space Agency, United States

Coauthor

Mr. Jason Dyer, United States

Year

2007

Abstract

Station Program Notes (SPNs) are documented anomalies in the International Space Station (ISS) on-board software.  SPNs seek to describe the anomaly and its impact on ISS operations, as well as offer an operational workaround.  All systems of the ISS are vulnerable to SPNs, including the Mobile Servicing System (MSS), Canada’s robotic contribution to the ISS project, used for the assembly and maintenance of the ISS.

In November of 2003, a survey of ISS Flight Controllers was performed in response to findings of the Columbia Accident Investigation Board (CAIB).  Conducted by staff of the NASA Ames Research Center Human Factors and System Safety group, this survey sought to identify organizational risks, and concluded that the ISS program’s critical vulnerability was “an over-reliance on human operators to work around malfunctioning software.” [1]  There are approximately 860 SPNs in existence today, of which approximately 215 documented anomalies are in the MSS, or robotics, software.  

This paper gives a description of what SPNs are and the processes and tools used to create and document SPNs in the ISS Robotics Systems group.  An overview of the MSS and reasons why it may be vulnerable to SPNs, including its complexity and distributed software architecture, are also presented.  The paper confirms the findings of the 2003 survey and discusses how changes in the ISS Robotics Systems group’s SPN philosophy since that time have been effective in reducing the number of SPNs for the MSS software, though these must often be weighed against providing increased functional capability.  Finally, recommendations that may further decrease the number of MSS software SPNs in existence and/or minimise their impact on flight safety are presented.

Abstract document

IAC-07-B3.I.05.pdf

Manuscript document

IAC-07-B3.I.05.pdf (🔒 authorized access only).

To get the manuscript, please contact IAF Secretariat.