The third day began much like the second. I caught the shuttle from UMD to Goddard, ate breakfast with some of my fellow participants, and left for our designated room in Building 26. When we arrived there, our first speaker had already begun setting up. The presentation was on the power subsystem, and our speaker had brought with him a number of examples of satellite power sources, including a variety of types of batteries and solar cells. In his talk, he explained how satellites gather, store, and deliver power to the other subsystems. Together we went through a few calculations regarding power budgets.
The presentation and exercises on the power subsystem were followed by a talk on the Astro-E2 mission from the perspective of a scientist. Much of the two weeks of the program was spent listening to and working with engineers, but this talk showed us things from the perspective of the scientists whom the satellites are built for. It also showed us some of the unique aspects of working on an international project, as Astro-E2 is being built as a collaboration between the United States and Japan. For example, Japanese engineers will rarely answer a question of the form "can you do this..." with "no". Instead, they will replay with "that would be difficult", and it took some time before the American scientists finally recognized the meaning of that phrase. The Japanese also do not name a mission until launch day, which is why Astro-E2 currently has the name that it does.
After lunch, we returned to the room for a presentation on the communications subsystem. This talk was one of the most technical we were given, accompanied by slides full of numbers making up link budgets. The calculations we did regarding communications were rather difficult, since none of us really had a solid background in the relevant science and terminology.
Finally, we ended the day with a tour of Goddard's clean room facilities. Goddard's main clean room is the largest in the whole world, and it is accompanied by many smaller clean rooms and assembly facilities. The various rooms house mock-ups and testing units for the Hubble Space Telescope, as well as facilities for testing hardware for flight by bombarding it with sounds, vibrations, and radiation. As we toured the rooms, some scientists were working with the Dexter robot that may or may not be used in Hubble's final servicing mission. The tour was very long and extensive, and we got a great idea of just how important Goddard is to NASA with regards to assembling and testing satellites.
Once again, a bus ride and breakfast started off another day in the College Freshman Intern Program. Our first talk this time was on structures and the mechanical subsystem of satellites. The mechanical subsystem is responsible for supporting the mass of all of the other subsystems and ensuring that the various component "boxes" are evenly distributed throughout the satellite body so that the satellite is balanced enough to be controlled easily. Finally, the mechanical subsystem must choose a shape for the satellite body, or "bus", and ensure that it fits inside of the rocket fairing.
After the talk, we were given an intensive mechanical exercise out of the SMAD book. There were a number of equations that we were required to solve, and none of us was really familiar with the topic. Nevertheless, I found the challenge quite enjoyable. However, the speaker made the point that real mechanical engineers never work through equations like we were then. Instead, they use computer programs, such as SolidWorks, to do the work for them. This speaker was also unique in that he lacked a complete college education. I found it remarkable that such an energetic speaker and important engineer for NASA could get to where he is without a college degree, and his story should give hope to those who love the kind of work NASA offers but may not perform well in a school environment.
After lunch we listened to a talk on the thermal subsystem, which is responsible for maintaining the temperature of a satellite. Certain instruments must be kept at constant, sometimes extremely cold, temperatures, which can be hard to do when the spacecraft is spending much of its time facing the sun without clouds or even an atmosphere for protection. The speaker passed around a few thermal control components, such as thermostats, thermistors, thermal blankets, and heat pipes. He also talked to us about some of the details on our project for the following week. We were assigned to design a mission to the moon that would prepare the way for a future manned landing. We were given requirements concerning the orbit, power, communications system, and mass, and we were to choose an instrument suite and design a space mission that could meet those requirements. Our mission was extremely similar to the real-life Lunar Reconnaissance Orbiter (LRO) mission.
We ended the day with a visit to the earth science research building, one of the newest buildings on the Goddard campus at its extended site across Soil Conservation Road. The presentation was in many ways similar to the scientific visualization presentation two days earlier, with lots of high-definition satellite imagery relating to the hole in the ozone layer, forest fires, hurricanes, and El Niño.
Each successive day there seem to be fewer and fewer people eating breakfast together and more and more people taking the opportunity to sleep an hour later. However, we all gathered together in time to travel together to the Integrated Mission Design Center, the IMDC. At the IMDC, a team of engineers, some of whom had presented to us earlier in the week, design entire space missions in 4 days! This rapid-design team gives scientists and other customers a sense of whether or not their idea for a space mission is feasible, given financial constraints, and is a method of mission design that has been copied by other academic and commercial design teams, such as Team-X out at JPL in California. They are able to do their job so quickly by maintaining a digital library of previous mission designs and commonly used spacecraft components.
The IMDC was pretty quiet while we were there, since their next project was not until Monday. However, the two team leaders and the launch systems engineer had plenty to say to us, both about mission design and life in general. The people at NASA value much more than simply getting their work done. The motto of the IMDC is "Working together to bring advanced concepts to reality ... in an environment of integrity, respect and excellence." It is encouraging to see how much everyone at Goddard loves their job. It is also amazing to see the variety of people who work for NASA. While many are scientists and engineers with advanced college degrees in their fields of work, others are certified airplane mechanics choosing which rockets to launch while still others are lawyers from Africa maintaining computer severs. Goddard looks to be one of the most diverse and enjoyable places of employment one could imagine.
After we had been introduced to the rapid mission design process, we split into two teams to begin work on our own lunar mission. Our first task was to assign roles to each member of the group. I decided to work on the spacecraft's orbit and communications subsystem, and I was additionally assigned the role of project manager. Before long, we had spent all of our six hours at the IMDC and it was time to head on home for the weekend.
