Tag Archives: ISS

Root Cause Analysis - Incident Investigation

ISS Supply Mission Fails

By Kim Smiley

An unmanned Progress supply capsule failed to reach the International Space Station (ISS) and is expected to burn up during reentry in the atmosphere along with 3 tons of cargo.  Extra supplies are stored on the ISS and the astronauts onboard are in no immediate danger, but the failure of this supply mission is another in a string of high-profile issues with space technology.

This issue can be analyzed by building a Cause Map, a visual format of root cause analysis.  A Cause Map intuitively lays out the causes that contributed to an issue to show the cause-and-effect relationships.  To build a Cause Map, “why” questions are asked and the answers are documented on the Cause Map along with any relevant evidence to support the cause.

So why did the supply mission fail? The mission failed because the supply capsule was unable to dock with the ISS because mission control was unable to communicate with the spacecraft.  The Progress is an unmanned Russian expendable cargo  capsule that cannot safely dock with a space station without communication with mission control.  Mission control needs to be able to verify that all systems are functional after launch and needs a communication link to navigate the unmanned capsule through docking.

Images of the capsule showed that two of the five antennas failed to unfold leading to the communication issues.  Debris spotted around the capsule while it was in orbit indicates a possible explosion.  No further information has been released about what might have caused the explosion and it may be difficult to decisively determine the cause since the capsule will be destroyed in orbit.

The ISS recycles oxygen and water to an impressive degree and food is the first supply that would run out on the ISS, but NASA has stated that there are at least four months of food onboard at this time.  The failure of this mission may mean that the cargo for future missions will need to be altered to include more basic necessities and less scientific equipment, but astronaut safety is not a concern at this time. The failure of this mission does put additional pressure on the next resupply mission scheduled to be done by SpaceX in June in addition to creating more bad press for space programs that are already struggling during a turbulent time.

To view a intermediate Cause Map of this issue, click on “Download PDF” above.

Root Cause Analysis - Incident Investigation

International Space Station Supply Ship Crash

By ThinkReliability Staff

On August 24, 2011, a supply ship heading to the International Space Station (ISS) crashed in Siberia, losing two tons of cargo.  However, the impact of this loss was much more than the two tons of cargo – it may lead to an evacuation of the ISS, which would become unmanned for some unknown period of time.

The crash of the unmanned Progress 44 supply ship, which was on its way to resupply the ISS, was caused by the emergency deactivation of the Soyuz rocket when a gas generator malfunctioned.   Until the specific causes of the malfunction are determined, manned Soyuz flights are grounded.  That means that a new crew cannot get to the Space Station to relieve the current crew.  Although the current crew has enough supplies for the time being, they cannot remain on the space station past December.  The spacecraft already at the station (their “guaranteed ride home”) are only allowed in space for 200 days – due to limited battery life and concern for degradation of rubberized seals from contact with thruster fuel.

Because of a lack of funding, American shuttles are now all mothballed, leaving the Russian Soyuz rockets the  only way to and from the space station.  Finding another way to get there by December is unlikely, leaving the attempt to determine and fix the problems with Soyuz the only hope for continued manning of the ISS.

We can examine this incident in a Cause Map, beginning with the impacts to the goals.  For example, although there were no safety goal impacts resulting from the crash of the unmanned ship, the customer service goal is impacted due to the potential of evacuating the ISS.  The production goal is impacted because of the grounding of manned Soyuz flights, and the property goal is impacted due to the two tons of lost cargo meant for the space station.  We begin our Cause Map with these impacts to the goals, asking “Why” questions to complete the analysis.  The amount of detail in the map is determined by the impact to the goals.  Because the crash may lead to the evacuation and continued unmanned operation of the space shuttle, once specific causes are determined, this Cause Map would become quite detailed.  For now, because the causes have not yet been determined, we begin with a simple map, which does capture the impacts to the goals and the basic information now known.

To view the Outline and Cause Map, please click “Download PDF” above.