As ASU’s first NASA mission begins Year 3, there are no blueprints for building the first spacecraft of its kind
It’s a spacecraft the size of a shoebox, and, if all goes well, it will launch on a voyage to the moon in about two years.
NASA greenlit the LunaH-Map mission two years ago. It’s the first NASA missionASU has instruments or roles on 11 NASA missions in flight, and a science team member on a 12th mission in flight. The university has seven more instruments in development for scheduled launches, and five missions (including LunaH-Map) in development. for Arizona State University’s School of Earth and Space Exploration. It’s going to look for ice on the moon, which can be used for water or fuel in the push to Mars.
It’s a lot of firsts. First deep-space cubesat mission. First test case for sending lots of little spacecraft tagging along on a big mission. First time NASA — a famously risk-averse organization — has said, “Go low cost and high risk.” And it’s the first interplanetary spacecraft built on ASU’s campus — one of only seven institutions in the U.S. where that is possible.
This past summer, LunaH-Map passed a huge milestone: a critical design review from NASA, an in-depth technical review to ensure a system can proceed into reality from plans and can meet stated performance requirements within cost, schedule and risk.
For principal investigator (PI) Craig Hardgrove and his team of engineers and scientists, proceeding into reality from plans is nerve-wracking beyond belief.
Hardgrove said people have told him, “If you’re not terrified every day, you’re not doing something genuinely new.” A NASA official told him it’s pretty much standard operating procedure for a first-time principal investigator to go through the meat grinder.
“I think as PI you can’t be an expert in everything, so it’s natural to be a bit freaked out by a lot of elements of the mission,” Hardgrove said. “To cope, I wind up asking a lot of questions. At some point you just have to trust the people working for you.”
In some ways, this mission is a return to the early days of the space program, where no one knew what would work and what wouldn’t.
“The people who work on this believe in it,” he said. “They believe it’s something that should happen. They believe there will be more of these tiny spacecraft in the future and that this is a new model of exploration for NASA.”
It’s an exercise in budget and risk.
How cheaply, both in terms of material and manpower, can you gather information from space?
“The whole thing is about risk,” Hardgrove said. “That’s what it feels like at this point. We’re in a good spot, but it feels like that’s really the exercise.”
Video by Ken Fagan/ASU Now
Fighting for space
There is no space on the spacecraft. Cubesats are miniature satellites (in this case a spacecraft) built to a standardized size and volume. One unit is about the size of a large Rubik’s cube. LunaH-Map will be the size of six of those put together — a 6u, in space-systems terminology.
LunaH-Map is the Rubik’s Cube from hell. Arguments have broken out about millimeters. “Can we get a millimeter there?” “NO!”
People also have to get their hands in it to assemble it. All the components on the 3-D-printed model fit together. But they have to be wired together too. And wires take up room.
Savannah Puckett is a software and hardware test engineer with AZ Space Technologies, a company specializing in design and manufacture of instrument and spacecraft avionics and software, which is contracted to help build LunaH-Map. She is also an ASU computer science grad.
“There’s a lot of things we have to work through as a team that a lot of other teams don’t have to deal with,” Puckett explained. “So bigger satellites, there’s more space to do things. Here, we don’t have a lot of space for wiring. Our structure is pretty compact. … We all have to work through how we’re going to fit these somewhat larger wires into this tiny little cereal box, basically.”
There are roughly 200 wires in the harness. They have to fit into a few centimeters on top of all the hardware. Bear in mind this is not like cramming speaker wire and HDMI cables behind your stereo receiver so they’re out of sight.
“We can’t let anything drop down,” Puckett said. “We have to make sure it’s all flat and secure, nothing’s going to rattle around when we send it out. So there’s not a lot of space to make sure the wires stay there, and there’s not a ton of space to make sure all of our wires are exactly where they need to be.”
Puckett’s job makes building a Swiss watch look simple. All of the components need to work, and none of them can interfere with one another.
“I think working on a watch would be a little bit easier,” she said.
Never done before
After launching, the rocket will drop off the cubesat about halfway to the moon. It will take LunaH-Map 70 days to reach the moon, using momentum from the rocket while making minor course corrections.
It will then begin a very slow descent to its final orbit around the moon. It will fly about 10 kilometers above the surface — unusually low for a spacecraft — and it will take 470 days to reach that altitude. It’s not the Millennium Falcon. The propulsion system provides about a quarter- to a half-ounce of thrust. That’s as much force as dropping a sheet of paper on your hand.
“We’re doing something that’s never been done before,” said Nathaniel Struebel, a senior majoring in aeronautical aerospace engineering, and thermal and structural engineer on the mission. “If we’re successful, it’ll open the door for a lot more.”
Aerospace engineer Joe DuBois is the structure design lead and integration and test lead on the team. One of the keys to making this mission a success from an engineering standpoint is cutting as much as possible from the vehicle. They ditched the idea of putting a camera on it a long time ago. It took up too much space and wasn’t absolutely essential.
Usually functions like command, data handling and guidance and navigation control are huge on spacecraft so they can include as many instruments as possible. Not on this one, DuBois said.
“Our spacecraft goes in a different direction by developing a very small spacecraft around a single instrument,” DuBois said. “There can be an increase in (mission) robustness by sending multiple, single-sensor spacecraft rather than a single, multi-sensor spacecraft.”
Weight is a factor everyone is keeping an eye on. The limit is 14 kilograms, just under 31 pounds. Southwest Airlines allows you more weight than that. Each component has to come in within its mass budget.
“We are relying on the great work done by our component suppliers to be able to accomplish the challenging requirements,” DuBois said.