工程师故事：打造一颗业余卫星(4)

Chips in Space: SuitSat-2 becomes ARISSat-1 - When we lost our suit! (not really)

Steve Bible

In the beginning, ARISSat-1 was to be SuitSat-2. It would have been deployed just like SuitSat-1: during an extra-vehicular activity (EVA), by pushing it away from the International Space Station (ISS).

SuitSat-2 was a grand science-fair project (or maybe today, a hacker space project – get it, hacker “space” project – never mind). Think about it, what if you were given a discarded Russian Orlan space suit and asked to turn it into an amateur satellite? Its mission: education – around the world! What features would you put on it?

Here are a few of the major features we decided on:

Communications transponder – UHF uplink and VHF downlink (can we talk?)

Cameras – four of them so we can see what it’s like in space

Solar panels – so that the battery can maintain a charge and operate for months

Transmit audio greetings from space in many languages – to generate interest via transmissions that are easy to receive with a simple radio or scanner

Telemetry – so that the health of the satellite is known and to promote interest in science and math.

And there were many unique design requirements for this project:

SuitSat-2 had to be easy for the cosmonauts to assemble. The Russian Orlan space suit was resident on the ISS. The electronics would be delivered to the ISS and the cosmonauts would assemble the pieces, forming SuitSat-2.

SuitSat-2 had to be easy to deploy. A handle was created for SuitSat-1 that would also be used for SuitSat-2, allowing the cosmonauts to hold the suit and push it away. The activation had to be easy, with positive/negative indicators as to its operational status.

SuitSat-2 had to be safe. There were several safety factors that had to be addressed in writing: electrical, snag and shatter hazards.

During the early years of our development, all form factors were designed to fit in and on the Orlan space suit. Basically, the electronics would be placed inside the space suit. The solar panels, control panel, cameras and RF/antennas would be mounted outside the suit. Our greatest challenge was resolving how we were going to mount all that “stuff” on the outside—the solar panels were the most challenging.

All that changed in July 2009, when the suit had to be discarded to make room on the ISS. We were working to complete the SuitSat-2 components to be shipped to Russia so that it could be ‘up-massed’ to the ISS in time. There was still too much work to be done, and we lost the suit (figuratively speaking). Quiz time – how did they dispose of that suit?

Now what were we to do? Our grand science-fair project changed parameters. The team regrouped and started work on a space frame.

The goal now was to use all the existing enclosures, solar panels and antennas—which were designed to attach to the suit—and mount them onto a more traditional satellite frame. We did not want to redesign all of the enclosures. And, the new space frame needed an easy method to deploy it by hand.

We mocked up a space frame using existing enclosures and solar panels, setting the size requirements. The solar panels basically dictated the overall frame size. These were space-rated panels given to us by NASA and taken from another project’s surplus. There are six panels on six sides of the craft. In order to protect the solar panels from being bumped, lexan covers were added. For deployment, we designed handles onto the corners of the frame.

Our space frame mockup

From the cross-sectional diagram, you can see that the battery, Internal Housekeeping Unit (IHU), transmitter and receiver RF units, Maximum Power Point Tracking (MPPT), and cameras all fit nicely inside the frame. Two of the four cameras are mounted with mirrors, allowing for photos to be taken in four axes. On the outside of the frame are the solar panels (six axis), the Kursk University experiment, antennas and the control panel.

A cross-sectional diagram of our satellite

As you can see, our grand science-fair project took many turns and twists during its development lifetime. You might view this project as a collection of features and specifications manifesting in a lot of electronics, wire, plastic and aluminum. But looking back on it, there was some amazing resilience and perseverance that our team put into ARISSat-1 to make it come to fruition.

In the next blog post, I’ll go into more detail about the electronics enclosures and what components are in them. In the meantime, ARISSat-1 is deployed and operating very well. Check out the below links for more background info and the latest news on this project. And, please post comments about what you’d like me to cover in future posts, as well as any questions I can answer for you.