By Angela Griffith
NASA’s plan to launch Discovery on its final mission continues to face setbacks. As discussed in last week’s blog, the launch of Discovery was delayed past the originally planned launch window that closed on November 5 as the result of four separate issues.
One of these issues was a crack in a stringer, one of the metal supports on the external fuel tank. NASA engineers haven identified additional stringer cracks that must also be repaired prior to launch. These cracks are typically fixed by cutting out the cracked metal and bolting in new pieces of aluminum called doublers because they are twice as thick as the original stringers. The foam insulation that covers the stringers must then be reapplied. The foam needs four days to cure, which makes it difficult to perform repairs quickly.
Adding to the complexity of these repairs is the fact that this is the first time they have been attempted on the launch pad. Similar repairs have been made many times, but they were performed in the factory where the fuel tanks were built.
Yesterday, NASA stated that the earliest launch date would be the morning of December 3. If Discovery isn’t ready by December 5, the launch window will close and the next opportunity to launch will be late February.
NASA has stated that as long as Discovery is launched during the early December window the overall schedule for the final shuttle missions shouldn’t be affected. Currently, the Endeavor is scheduled to launch during the February window and it will have to be delayed if the launch of Discovery slips until February.
In a situation like this, NASA needs to focus on the technical issues involved in the repairs, but they also need to develop a work schedule that incorporates all the possible contingencies. Just scheduling everything is no easy feat. In additional to the schedule of the remaining shuttle flights, the timing of Discovery’s launch will affect the schedule of work at the International Space Station because Discovery’s mission includes delivering and installing a new module and delivering critical spare components.
When dealing with a complex process, it can help to build a Process Map to lay out all possible scenarios and ensure that resources are allocated in the most efficient way. In the same way that a Cause Map can help the root cause analysis process run more smoothly and effectively, a Process Map that clearly lays out how a process should happen can help provide direction, especially during a work process with complicated choices and many possible contingencies.
By Angela Griffith
Launching a space shuttle is a complicated process (as we discussed in last week’s blog). Not only is the launching process complex, finding an acceptable date for launch is also complex. This was demonstrated this week as the shuttle launch was delayed four times, for four separate issues and now will not be able to happen until the end of the month, at the earliest.
There are discrete windows during which a launch to the International Space Station (which is the destination of this mission) can occur. At some times, the solar angles at the International Space Station would result in the shuttle overheating while it was docked at the Space Station. The launch windows are open only when the angles are such that the overheating will not occur.
The previous launch window was open until November 5th. The launch was delayed November 1st for helium and nitrogen leaks, November 2nd for a circuit glitch, November 4th for weather, and November 5th for a gaseous hydrogen leak. After the November 5th delay, crews discovered a crack in the insulating foam, necessitating repairs before the launch. These delays pushed the shuttle launch out of the available November launch window. The next launch window is from December 1st through 5th, which gives the shuttle experts slightly less than a month to prepare for launch, or the mission may be delayed until next year.
Although not a lot of information has been released about the specific issues that have delayed the launches, we can put what we do know into a Cause Map. A thorough root cause analysis built as a Cause Map can capture all of the causes in a simple, intuitive format that fits on one page. Once more information is released about the specifics of the issues that delayed the launch, more detail can easily be added to the Cause Map to capture all the causes for the delay. Additionally, the timeline can be updated to reflect the date of the eventual launch.
To view the problem outline, Cause Map, and launch timeline, please click on “Download PDF” above.
By Angela Griffith
The Space Shuttle Discovery is expected to be launched November 4th, assuming all goes well. But what does “all going well” entail? Some things are obvious and well-known, such as the need to ensure that the weather is acceptable for launch. However, with an operation as complex and risky as launching a shuttle, there are a lot of steps to make sure that the launch goes off smoothly.
To show the steps involved in shuttle launch preparation, we can prepare a Process Map. Although a Process Map looks like a Cause Map, its purpose is to show the steps that must be accomplished, in order, for successful completion of a process. We can begin a Process Map with only one box, the process that we’ll be detailing. Here, it’s the “Launch Preparation Process”. We break up the process into more detailed steps in order to provide more useful information about a process. Here the information used was from Wired Magazine and NASA’s Launch Blog (where they’ll be providing up-to-date details as the launch process begins).
Here we break down the Shuttle Launch Process into 9 steps, though we could continue to add more detail until we had hundreds of steps. Some of the steps have been added (or updated) based on issues with previous missions. For example, on Apollo I, oxygen on board caught fire during a test and killed the crew. Now one of the first steps is an oxygen purge, where oxygen in the payload bay and aft compartments is replaced with nitrogen. On Challenger, concerns about equipment integrity in extremely cold weather were not brought to higher ups. Now there’s a Launch Readiness Check, where more than 20 representatives of contractor organizations and departments within NASA are asked to verify their readiness for launch. This allows all contributors to have a say regarding the launch. One of the last steps is the weather check we mentioned above.
Similar to the Launch Readiness Check, we can add additional detail to the Launch Status Check. This step can be further broken down to show the checks of systems and positions that must be completed before the Launch Status step can be considered complete. Each step within each Process Map shown here can be broken down into even more detail, depending on the complexity of the process and the need for a detailed Process Map. In the case of an extremely complex process such as this one, there may be several versions of the Process Map, such as an overview of the entire process (like we’ve shown here) and a detailed version for each step of the Process to be provided to the personnel who are performing and overseeing that portion of the process. As you can see a lot of planning and checking goes into the launch preparations!