Bitcoin has already spread rapidly across the globe, but now one of the currency's core developers wants to take it where no virtual currency has gone before - space.
Developer Jeff Garzik plans to launch several tiny satellites into space which will serve as a node on the bitcoin network.
Historically, it has cost tens or hundreds of millions to launch satellites into space, but a new generation of privately-funded, bootstrapped satellite services has changed all that.
Garzik's project involves building 'cubesats', which are standard, small-sized satellites, typically measuring 10cm on all sides. These satellites can be launched into space cheaply by piggybacking on other payloads.
Garzik estimates that it would cost just $2m to get one into orbit. Once in space, it would serve as an alternative way to distribute block chain data. "Information wants to be free," Garzik said in his post about the project.
But can't it be free on the ground? The Internet already does a pretty good job of letting around 5,000 bitcoin nodes distribute information. It was built to route itself around damage, and we rely heavily on it.
If the Internet ever failed, we'd presumably be too busy trading chickens to worry about whether we could confirm cryptocurrency transactions.
Beating Sybil attacks in space
Garzik explained that a bitcoin node depends on other nodes for its view of the network, he said:
"It is not an 'internet-melts-down' scenario, but a more limited 'thousands-of-nodes-attacked-at-once' scenario that happens on a daily basis on the Internet."
One such attack, named a Sybil attack, focuses on peer-to-peer networks like bitcoin. In an attack like this, malicious nodes surround a victim node and pass it false information.
"Bitcoin nodes are ultimately at the mercy of the data they receive from outsiders," Garzik says.
"All it takes is one honest source of block chain data to defeat a Sybil attack and similar attacks. Eventually, the honest block chain with the largest proof-of-work will win the day."
That honest source would be in orbit, and it's better to put it up there because satellites are great at one-to-many communications. It could beam blockchain information to any node that wanted to communicate with it.
The bandwidth required for this satellite wouldn't be huge, 1MB per minute should do it.
The cubesat would get its data from multiple groundstations, which would act as normal peer-to-peer nodes, but would verify that the block chain information was correct before transmitting it.
That data would initially be the latest bitcoin block, which the satellite would broadcast repeatedly. In the future, it would broadcast recent chains and transactions.
To boldly go
Garzik has two mission profiles for his satellites. One will involve between four and six of these devices, with which he believes he can get full earth coverage (or at least major continents).
The second would see a single satellite go up. He's hoping that the satellite(s) would help to serve bitcoin users in remote areas where traditional connectivity is patchy.
Even if the full network didn't deploy, bitcoin users would at least be able to access stellar block chain data for a small amount of time each day, and this would still carry significant value, he says.
"Any bitcoin participant on the ground can still have significant value from reading even 25% of the satellite broadcast," Garzik reasons.
"The point is to discover 'honest' blocks with valid proof of work. The network is self-correcting, even given a reduced trickle of valid blocks."
There are multiple phases to Garzik's project.
Phase one will see the creation of a team - which will flesh-out the cubesat specifications, price-out leased bandwidth, and workout specific data needs. Phase two will see the build and launch of the first satellite.
The money for the second phase isn't coming through the block chain just yet. Garzik posted about the project on 15th November, announcing a donation address and two sponsors: himself and Bitcoingrant.org. At the time of writing, the wallet address was yet to receive more donations.
Nevertheless, there is sufficient interest to get the project moving. Garzik says:
"Fundraising has not begun in earnest, though donations are solicited now, because BitcoinGrant.org and my funds should suffice to complete phase one."
He hopes to have a demonstration satellite in orbit by 2016-18. "Additional interest and funding will dictate how large the network may grow," he added.
He claims to have verbal commitments for full cubesat construction in phase two, and says that these commitments also cover around 25% of the launch's costs.
Earth in Space Image via Shutterstock