A USB standard for satellites? Slingshot 1 goes into orbit to test one

Testing new satellites and space technologies has never been easy exactly, but it could certainly be Easier. Slingshot 1, a 12U Cubesat mission that just launched via Virgin Orbit, is an attempt to make building and testing a new satellite as easy as plugging a new keyboard into your computer.

To say it’s “USB for space” is simplistic… but not wrong. The Aerospace Corporation team that designed the new system makes the comparison themselves, noting that the military has made several attempts to create just that with the Space Plug-and-Play (SPA) architecture, which is became the Modular Open Network ARCHitecture (MONARCH), and the Common Payload Interface Standard (CoPaIS). But the approaches didn’t take off like, say, the standard Cubesat – which, by the way, Aerospace also pioneered.

Slingshot 1’s goal is to create a standard satellite bus that is as adaptable and easy to use as USB or ATX, using open standards but also meeting all necessary requirements for safety, power, etc. . :

[Slingshot] offers more agility and flexibility in satellite development through the use of plug-and-play modular interfaces. These interfaces rely on open source systems to avoid proprietary lock-ins that can block development, as well as standardized interfaces for payloads that would not require a custom satellite bus. These interfaces define the power, command, control, telemetry, and mission data that may be required for the payloads. Without a set of common standards, these payload-to-satellite bus requirements are determined by different satellite bus manufacturers. Slingshot eliminates this uncertainty by reducing the number of requirements and interface complexity and creating an open payload interface standard called Handle.

How will it avoid the common pitfall encountered by aspiring standard setters, immortalized by XKCD: there are now N+1 standards?

Well, leaving aside the rather deplorable state of standards in the satellite world, if any, the team decided to base it all on Ethernet, which already underpins a huge amount of networking in the world.

“Basing the Handle standard on Ethernet builds on the large ecosystem of hardware and software tools developed for this very common interface, essentially taking the most common Earth system standard and migrating it for satellite use,” said said Dan Mabry, senior specialist engineer at Aerospace. “We have adapted the network for low power consumption, but still support gigabit per second communications between devices with no custom software development required to adapt the network to each new application.”

And as he said when Aerospace wrote Slingshot for his own purposes last year: “When a payload plugs in, it will be instantly recognized and working, and all data streamed will reach the spacecraft’s downlink. without any software setting or adjustment. Moreover, since it is an on-board network, the data of this payload is also seen by all the other payloads. Payloads can easily collaborate in real time, and distributed smart sensors and processors are coupled by the core architecture.

Combine that with a power hub that can intelligently meet a variety of needs and a modular case that makes the whole thing look like the back of a neatly organized gaming PC, and you have a plug and play recipe. play which really makes things easy for the future designer.

The Slingshot 1 configuration assembled without its outer casing.

As Slingshot’s Program Manager, Hannah Weiher said, “It works to reduce interface complexity and support different satellite buses and payloads with minimal to no interface adaptation needed. Handle was key to a streamlined payload integration process on Slingshot 1 where we had a wide range of payloads with different requirements and this allowed us to be able to integrate the volume of payloads we have made into a satellite the size of a shoebox.”

Of course, it’s not enough to just send a barebones interface – imagine sending a PC case with nothing in it. To see if it works, you need things attached, and luckily there’s a ton of experience and abilities that Aerospace has saved since Slingshot’s genesis in 2019.

  • Handle – Plug-and-Play Payload Electrical Interface Module

  • Bender – embedded Ethernet and network routing

  • t.Spoon – Modular Mechanical Interface

  • t.Spoon Camera – Plug-and-play camera module

  • t.Spoon processor – Zynq Ultrascale+ integrated processing

  • Starshield – Embedded Malware Detection

  • CoralReef – Coral Tensor Processing Unit

  • STarfish – ARM Cortex-M33 Secure Embedded Processing

  • SDR – S-band Software Defined Radio (SDR) Downlink

  • Keyspace – Cryptographic services for SmallSats

  • Lasercom – Next Generation Space/Ground Lasercom Downlink

  • ROESA – Using Internet of Things protocols to connect payloads

  • Vertigo – Reconfigurable Attitude Control System

  • Blinker – GPS transponder for space traffic management

  • Hyper Hydrogen Peroxide Thruster – SmallSat

  • ExoRomper – Artificial Intelligence and Machine Learning Testbed

Some of them are more or less self-explanatory, like the various components of t.Spoon, being the basic mechanical elements that tie it all together. And of course you need a nice software defined radio downlink. But a tensor processing unit and machine learning test bed on a satellite? Internet of Things protocols? Crypto services?

CG view of Slingshot expanding to show its components.

When I spoke with the team during a visit to the Aerospace labs a while back, they talked about how much of what’s on Slingshot is unprecedented in some ways, but is more about adapting common terrestrial tasks to the extremely formalized and limited context of a satellite. hardware and software.

Suppose you have three or four payloads sharing CPU and storage. How do you ensure that their communications remain secure? The same way you would on the ground, but adapted to the light processing, limited power and unusual interface of a spaceship. Sure, space-safe processing and communications have already been done – but it’s not like there’s a plug and play version where you can just click a checkbox and suddenly your load useful is fully encrypted.

Similar is ExoRomper, which has an externally mounted camera hooked to the TPU. There’s been a bit of AI in space before, but never a setup where you can say, oh sure, you can add cloud recognition to your satellite, that’ll take 2 watts, 20 cubic centimeters and 275 grams. This one in particular is set up to monitor the satellite itself, looking at lighting conditions, which seriously affects thermal loads and power handling. Why shouldn’t your satellite have its own satellite, monitoring to make sure there are no hot spots on the solar cells?

Data will arrive from Slingshot as it tests its many components and experiments over the coming months. It could be the start of a new modular era for small satellites.

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