Stress-testing a space-based blockchain

SpaceNews interviewed Hasshi Sudler, Villanova adjunct professor and CEO of the Internet Think Tank, to learn more about future blockchain constellations.

Villanova University researchers are conducting a series of experiments that could help define future blockchain constellations.

Researchers from Villanova’s College of Engineering programmed a singleboard computer to serve as a node for the Ethereum Private blockchain on a cubesat scheduled to be launched in December with the educational nonprofit Teachers in Space on Firefly Aerospace Alpha rocket.

Once in orbit, Villanova researchers led by Hasshi Sudler, adjunct professor of engineering, will test the ability of the blockchain node to process transactions. As a follow-on experiment, the researcher team plans to launch three satellites to test transactions between blockchain nodes as well as between satellites and the ground stations.

Sudler was an engineering student at Villanova when he became interested in space. His engineering research involved building experiments as part of NASA’s Getaway Special to send on the Space Shuttle. In 2003, however, NASA discontinued the Getaway Special experiments program due to the Space Shuttle Columbia accident.

“As fate would have it, I’m back at the university as a professor, fulfilling Villanova’s mission of launching a space experiment,” Sudler told SpaceNews.

In addition to his work at Villanova, Sudler is chairman and CEO of the Internet Think Tank, a cybersecurity consulting firm with offices in the United States and Japan.

What are the space applications for blockchain?

The first is intersatellite transactions. We see a lot of different institutions putting up their own satellites to take images or detect weather conditions. Other satellites may want access to some of that unique information. One satellite can request information from another satellite and even pay for it over blockchain. The receiving satellite can deliver that information to customers on Earth.

If the information is needed under time-critical situations, a satellite overhead of a customer can procure that information and rapidly transmit it down to Earth. In this case, you need satellites capable of talking to one another and transacting data.

Tell me about your upcoming space experiment.

We will take a very systematic approach to analyzing the behavior of blockchains in space. We’re going to start with a single satellite acting as a node and have that talk to several other nodes on Earth.

What’s unique about this blockchain, however, is that the satellite node will be popping in and out of the network. The satellite will be out of communication for most of the 90 minutes it takes to orbit around the Earth.

This can create some interesting dynamics. If new information is coming onto the network, you want to make sure that all of those nodes are updated with the same information, particularly for small networks. How do you ensure that all the satellites can synchronize within a reasonable period of time?

There’s another interesting dynamic. Satellites are vulnerable to radiation, particularly from the solar flares.

If someone were to attempt putting up a large network of blockchain nodes in space to create a blockchain network, it’s possible that if the sun were to have a major solar event, some of those satellites may malfunction or their information may be corrupted. We need to understand the limits of the blockchain operating under these harsh conditions. If we were to lose satellites, what does this do to the network? How would the satellite network overall begin to behave and what are the security implications?

How will you test that?

We’ll be testing a set of transactions, moving tokens, deploying smart contracts and performing a series of transactions using these smart contracts. We’re going to test the satellite during five stages of its orbital path: before it rises, coming up on the horizon, passing overhead, when it’s setting and finally beyond the point where we can see it. We essentially want to see how the transactions and synchronizations are handled at each stage.

Would this help you figure out how many satellites to put in a constellation?

That’s right. This begins to give us the information that would factor into how you design your constellation, because you would know when you can successfully synchronize these nodes. It will be interesting to see how the behavior of the nodes in space may vary from the behavior of the nodes on Earth.

How would a blockchain network in space be used?

Certainly, there will be intersatellite transactions. The market for acquiring satellite data is rising quickly, making intersatellite transactions for that data more in demand. Organizations are starting to look at intersatellite transactions also as a means of monetizing their satellites. The ability to transact between satellites also allows organizations to lower expense by leveraging the capability and data of satellites already in space rather than launching its own custom satellites.

Also, more people are traveling to space. This year alone has been the debut of civilian travel into space. Over time, humans will be staying in space for longer periods and eventually living there longer term. There will be a point where peer-to-peer transactions will be desired.

A person at a space hotel, for instance, will want to make transactions with the hotel directly. People on the moon or Mars will want to transact with each other. Now, they could transact in an ecommerce manner with all those signals coming back down to Earth, to be settled by trusted third parties — banks and so forth. The issue we have with that is of course latency. If you wanted to start doing a lot of transactions, this delay will not be desirable.

If you have blockchain in space, you now have the ability for peer-to-peer transactions that are still reliable, still transparent and still quite secure because the blockchain is holding that information.

The long-term goal here is to establish the network infrastructure needs for this emerging space economy. We’re at the very beginning. Certainly, we have internet in space. Blockchain is yet another network that will be in space and it will serve the purpose of supporting the transaction of both money and information for future generations of space dwellers.

How many satellites are likely to be in a blockchain constellation?

You would want one satellite to be able to see one or two other satellites at any given point in time. That means that if you were to do a transaction, the network itself could replicate that information at near the speed of light.

I calculate that you can do this with a minimum of about 150 satellites.

What are the challenges?

We are investigating radiation-induced errors on blockchain satellites. If a satellite is exposed to sun or the Van Allen belts, you can get a single-event upset. If a satellite is in space long enough, it can accumulate enough charged particles through the Van Allen Belts to have a high probability of flipping a bit and actually experiencing an error. People deploying these blockchain networks need to be aware of these issues as such errors could reduce the number of nodes supporting the integrity of the overall network. Perhaps it means that people need to swap out node satellites before they start showing symptoms of failure.

Now the question that we’re really interested in is how would radiation exposure change the behavior of a node? Could we even trust the blockchain anymore? Blockchains are all about trust. Some of the information is very sensitive so the network would really need to be resilient to prevent loss of trust and tampering.

We have to understand the extent to which we can trust the network under a harsh space environment and also a dynamic environment because these nodes are moving around all the time.

We need to understand the limits and find out where it fails. Based on these findings, we can devise solutions.

This article originally appeared in the November 2021 issue of SpaceNews magazine.