Every decision the spacecraft designers make has cascading effects. Science goals affect the instrument payload necessary for a successful mission. The instrument payload affects the command and data subsystems (which handle signals sent from Earth and data to be returned). This, in turn, affects spacecraft telecommunications hardware (which performs the actual transmissions). It can affect the power necessary to keep the spacecraft alive. And so on. If scientists desire something as seemingly simple as a higher-resolution image, dominoes can fall in such a way that the spacecraft can no longer regulate its fuel temperature or is too heavy to launch.
In developing a spacecraft, Team X engineers for each subsystem work in parallel. You’re building a house all at once. While someone is building the chimney, someone else is building the roof and another is designing the air-conditioning system. Because each spacecraft subsystem affects every other, consoles are arranged so that the people who need to talk to each other can lean over and chat easily. Periodically, the team checks to see whether the spacecraft design “closes”—whether the myriad parts of the system work with each other to form an internally consistent whole that achieves its objectives given the space provided and for the correct price.
These studies, which generally take three days or less, can be intense for would-be mission teams. “You’re sitting there starstruck,” says Lindy Elkins-Tanton, the principal investigator for Psyche, a mission matured in the Innovation Foundry. “All the consoles with all the experts are manipulating subsystems, and numbers are clicking this way and that, and mass and power and dollar totals are changing, and the experts are shouting back and forth with each other.” If we use this trajectory, how much xenon do you need? If we measure this instead of that, how do your power needs change? What mass is that instrument? What kind of orbit control will achieve that? She says it has an energy similar to Mission Control, in terms of focus and import.
The systems do not always close—they didn’t at first with Psyche, even after two rounds with Team X. Scientists often must reconsider their goals in the face of mass, power, fuel, or funding.
“During the process, I was feeling really good,” Elkins-Tanton says. “We had made the hard decisions, we brought really useful information, we could get the power, we could get the mass—and then cost came through way above the cost cap. I almost couldn’t believe it. I just thought, ‘That’s not possible.’” Eventually, the Psyche team opted to use an off-the-shelf spacecraft bus, the component that forms the main body of the spacecraft. It was much less expensive than the custom-made bus they’d originally planned to build, and that solved the cost problem.
“To me, the magic of Team X is it gives you structure, and it gives you the perspective of what a mission looks like [to] a disinterested outside party,” she says. A team of scientists can go into Team X having convinced each other of the rightness of their plan, their prospective payload, and the measurements they intend to make. In some of those cases, she notes, “it is very important for someone to tell you, I’m sorry, but that does not work.”
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