Pendulum’s Spacewalk receives a Web3 Foundation grant to bridge Stellar and Polkadot

Published in
4 min readJun 7, 2022


We are thrilled to announce that Pendulum has received a grant from the Web3 Foundation for developing Spacewalk, the first bridge between Stellar and Substrate-based parachains. Accepted as part of Wave 13 of the Web3 Foundation grants program, Pendulum has developed a bridge based on XCLAIM and interBTC.

Pendulum has delivered the first milestone for the Web3 Foundation grant to develop Spacewalk, a bridge between Substrate-based parachains and Stellar which enables asset transfers to and from Stellar.

Spacewalk is the first bridge between the Stellar network and the Polkadot/Kusama ecosystems. It is implemented as a Substrate pallet and allows any Substrate-based blockchain to implement a direct Stellar bridge.

“We can greatly benefit from the Web3 Foundation’s support and ongoing research about blockchain technologies as it allows us to step on the shoulders of giants and share knowledge with a great community of blockchain enthusiasts that lay the foundation for the Web3 future. We can also bring value to the Polkadot community by opening the gate for stable tokens and by collaborating on projects that bring new technology to the ecosystem.” — Dr. Torsten Stüber, CTO of Pendulum

Bridge design based on XCLAIM and interBTC

Pendulum will implement Spacewalk as a Substrate pallet, a component that can be plugged into any Substrate based blockchain.

Stellar is not smart contract capable — therefore the Spacewalk bridge design is based on XCLAIM. XCLAIM is a framework for achieving decentralized, trustless and efficient cross-chain transfers.

XCLAIM has been implemented and further improved by Interlay for the open source Bitcoin bridge interBTC. Spacewalk is based on the interBTC implementation. The term interBTC is used both for the bridge and for Bitcoin that is available on a Substrate-based chain.

The architecture of Spacewalk consists of the following components:

  • Vaults: this is a set of escrow accounts used to lock assets in Stellar. Their behavior is defined in XCLAIM and interBTC. Spacewalk will allow the bridging of arbitrary Stellar assets.
  • Bridge Pallet: this is the main component of the Spacewalk bridge that implements all logic on the side of the Substrate-based chain. Its behavior is based on interBTC.
  • Stellar Oracle: is a decentralized system that provides information about the state of the Stellar network to the bridge pallet. In interBTC this is implemented through a Bitcoin chain relay.

Why Web3 Foundation?

Web3 Foundation funds research and development teams building the technology stack of the decentralized web. It was established in Zug, Switzerland, by Ethereum co-founder and former CTO Gavin Wood. Polkadot is the Foundation’s flagship project. Web3 Foundation’s network of industry experts provides a great opportunity for Pendulum to learn from the best.

Pendulum aims to become a critical piece of Web3 infrastructure, therefore, Polkadot stands to benefit from more integrations and railroads connecting it with multiple traditional and blockchain ecosystems, like the Stellar <-> Pendulum Spacewalk bridge for example.

Spacewalk Roadmap

The Spacewalk roadmap is split into three milestones:

  • Milestone 1: Define the fundamental structure of the project and integrate multi-asset support
  • Milestone 2: Implement collateralization and liquidation of vaults when using arbitrary Stellar assets
  • Milestone 3: Implement the Stellar oracle

Work on the second milestone has just begun.

Spacewalk Team

The team is spearheaded by Dr Torsten Stüber (CTO) and Gonzalo Montiel (Lead Engineer). Dr Torsten’s Ph.D. in Theoretical Computer Science and 7+ years experience in theoretical computer science, natural language processing and cryptography, including the authoring of a WASM cryptographic library, are key behind the progress of Spacewalk. Equally, computer software engineer Gonzalo’s 10 years experience in the software industry means Spacewalk is in good hands. For full details of Spacewalk’s constantly growing team of blockchain experts click here.

What’s next for Pendulum?

Pendulum’s next goal is to win a Kusama parachain auction and launch a canary version of Pendulum. After running some intense testing on Kusama, Pendulum will be ready to compete for becoming a Polkadot parachain.

Pendulum is looking for collaboration with Polkadot parachain projects — reach out to us if you want to start a conversation, and sign up for the newsletter if you are interested in supporting Pendulum’s launch on Kusama via a crowd loan.

About Pendulum

Pendulum is an open-source blockchain built on the Substrate framework that aims to establish the missing link between the fiat and the DeFi ecosystems through a fiat-optimized smart contract blockchain.

About Web3 Foundation

Web3 Foundation funds research and development teams building the technology stack of the decentralized web. It was established in Zug, Switzerland by Ethereum co-founder and former CTO Gavin Wood. Polkadot is the Foundation’s flagship project. For more information, visit




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