When I bunked in at the program office I was given a stack of reports to read that described the satellite in detail. It soon became apparent that I was dealing with a huge, complex, military satellite that contained a large optical and other sensors, and many electronic subsystems. In analyzing the satellite I learned that at least one-third of the satellite weight was in structure, and I felt that I could rely upon my discipline of structures in dealing with this component. However, I needed the staff to help me better understand the remaining subsystems so that I could work with them in designing alternative configurations of higher weights and reliabilities and lower costs.
Such help and cooperation were not forthcoming. When it became clear that I would not receive the support of the program office staff, I reported the impossible situation to my supervisor. Instead of demanding the program office to cooperate with me, which he could have done by virtue of his position, he took my suggestion that I ask TRW if they would be interested in working with me. I explained that TRW appreciated the value of the MCD criteria, and that we had developed a close relationship by working on the TRW LEMDE engine configuration as the main propulsion subsystem for the MCD/SLV. Besides I was familiar with many TRW personnel because we had once been part of the same organization; namely, Ramo Wooldridge and Space Technology Labs.
The satellite division at TRW was receptive to working with me. I briefed a group of about six senior designers and the assistant manager of the division. Afterwards, the group had a whispered bull session. Then one member of the staff spoke up and said that they believe they understand the MCD criteria as it applies to payload design, and that they anticipate its use would decrease payload cost by about 5%. Fortunately the assistant manager of the division was not in agreement with the evaluation. He instructed one member of the group to work with me.
When I later met with the designated individual, he suggested that he study a relatively simple, existing satellite, namely VELA, which TRW fabricated and was first launched in October 1963. The satellite had 12 X-ray and 18 neutron and gamma-ray detectors, and was powered by solar cells. He agreed to attempt to develop one or more designs of higher weight and lower cost and, hopefully, to the same or higher level of reliability.
When I met with him next I found that he had taken each subsystem and designed it to several levels of decreasing sophistication, with commercial and laboratory hardware representing the end points of highest weight and lowest cost. He presented the results of his work in graphical form in the manner shown in Fig. 3 of the March 27, 1997, Column. Most striking about these curves, which arranged themselves in a vertical array, was that the initial slopes from point A to point B were greater than I had anticipated; in other words, initial increases in the weights of the minimum weight subsystems decreased costs appreciably. This was shown to be true for all subsystems.
Shortly after this meeting my supervisor advised me that the CEO of TRW had spoken with the president of Aerospace on the subject of this breakthrough in reducing the high cost of payloads. However, I became skeptical of the value of this news when I lost contact with the TRW designer. The situation revealed itself when I was officially told that TRW will not adopt the MCD criteria in the design of their payloads. In tapping the grapevine, I learned that TRW decided, after much high-level discussion, that it would be economically foolhardy to adopt the MCD criteria.
This ended my MCD payload design effort. This part of my assignment was accomplished, but obviously not with the documentation I had anticipated. However, the TRW study added to my confidence in saying that MCD payloads could cost appreciably less, and that their cost could be further reduced when they are designed to be launched by lower cost launch vehicles.
I answered the third question by presenting and discussing the following figure.
Methodology for Selecting Discrete Payload Designs and Launch Vehicles
In previous descriptions of the MCD criteria, I assumed the cost-weight relationships of launch vehicles and payloads to be continuous, and that the optimum combination of payload weight and launch vehicle occurred when the local slopes of the cost-weight relationships for payloads and boosters are equal and opposite; that is, when the sum of the payload and launch vehicle costs are a minimum.
In practice, there may be a stable of launch vehicles of different capabilities, perhaps as shown by points A, B, C, D and E. The payload designer may have chosen to configure discrete MCD payload designs, and these are as shown as points 1, 2, 3, & 4, where Design 1 represents the minimum weight design.
The figure is designed to illustrate the following points:
I know of no other MCD payload study that has been conducted, although
several approaches have been used to lower the cost of payloads. A current
popular approach is to limit the payload mission requirements.
| Do
you believe it is feasible to design minimum cost payloads?
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Next Column: Why No Start-up Company Has Built an MCD/SLV.