In the year 2122 TerraMars LLC is specialized in technical maintenance of propulsion engines of family-size passenger spacecraft (FPS), and its facility is located not far from Garni Crater Spaceport. On average, 7 FPS from all over the Solar System enter TerraMars dock per minute.

Once a FPS is in the dock, the automated registration system (ARS) takes6 secondsto record the FPS data, such as the owner, spaceport of registry, serial numbers of the spacecraft and its engine, history of operation, etc.

If the upfront data indicate the FPS is too old or severely damaged, the ARS does not use the mentioned 6 seconds and the FPS is moved to spacecraft junkyard (SJ) in no time for teardown and recycling, and the process ends there.

And if the data indicate it is for engine maintenance, then after 6 seconds of registration/recording at ARS, the FPS is moved to engine diagnostics bay (EDB), where the engines are examined by one of the three identical ED systems to determine the maintenance mode. Each ED system completes an engine diagnostic on average in 20 seconds and determines whether the engine must be removed from the FPS, or the maintenance can be done without removing it.

If the engine maintenance can be done without removing it, the FPS is directed to Chamber #1 (C1), whereas if it must be removed, then to Chamber #2 (C2). On average, 25% of spacecraft are sent to C1 and 75% to the C2.

The maintenance robot at the C1 takes on average 4 seconds to do the job, whereas for the robot at C2 unmounting, performing maintenance and mounting back an engine it is three times as long: 12 seconds.

Finally, FPS from both Chambers are moved to Finish & Launch Pad (FLP), where the new information is recorded in the database, FPS are washed by a stream of ions, placed on a platform and launched into space for an unmanned flight to their spaceport of registry. This last process up to the moment of launching takes 8 seconds.

1. Draw a process flow diagram using correct flowchart symbols.

2.

(i) What is the most convenient throughput or output rate measurement unit here and why?

(ii) What are the output rates of each stage in the process?

3.

(i) What are the utilizations for each stage?

(ii) Are these values appropriate/optimal and which of the stages work in the most optimal manner?

(iii) If any values are not appropriate/optimal, how might you redesign the process? Explain.

4. A new condition is added. At the C1, the robot has additional instant diagnostics capability and may discover that spacecraft engine still needs to be removed. In such case, the robot immediately sends the FPS to C2. It has been recorded that the robot does this in 60% of the cases.

(i) How does this change affect your answers to the questions in the question 3 above? Calculate, explain and comment.

(ii) Make a new diagram with the mentioned addition.

This is the way I drew Question 1's flow chart. If it is correct, I hope it helps in answering the other questions.

Is the FPS too old/ Yes Moved to SJ for Start severely teardown and recycling damaged ? enters aMars ock No ARS records FPS data 6 seconds EDB examination 20 seconds EDB examination 20 seconds EDB examination 20 seconds No Chamber #1 Engine Maintenance (25% of spacecraft) Does the engine 4 seconds have to be removed? Yes Chamber #2 Engine Maintenance and un/mounting (75% of SC) 12 seconds Finish and Launch Pad 8 seconds En