RS1 Flight 1 Update



In our first attempt, we had a flawless day of operations until 75% propellant fill at T-30 minutes. At that time, a vendor valve in our Stage 1 fuel pressurization system failed. This led to a gradual, and then more rapid leak of helium into our fuel tank. We scrubbed the launch and safed the vehicle for the day.


We have worked with the vendor to characterize this problem, made replacements, and retired the issue.



In our second attempt, we had another smooth day of operations and entered terminal count. During ignition at T-1.8 seconds, we aborted on low pressure in half of our gas generators.


We determined that the incomplete ignition was due to insufficient LOx conditioning and chill-in –  we had reduced our chill volume since static fire to preserve LOx for flight. By reverting to a more generous LOx chill, we retired the issue.



In our third attempt, we had another great day of operations and once again entered terminal count. During ignition at T-1.75 seconds, we aborted on low pressure in our main chamber TEA-TEB system. We cleared the gas generator hurdle from F1A2 but aborted on the next criteria at main chamber ignition.


In this case, we had triggered the abort by just 1psi. This issue has been retired by updating our abort threshold to be marginally lower.


This one was close. If we had been just 0.3% less conservative, RS1 would have flown that day. A tantalizing end to the week for our team, but you have to strike a balance between false positive aborts (scrubs) and false negative aborts (damage). We were a bit too biased towards avoiding false negatives this time.



We are ready for our next attempt. The rocket is healthy and our operations have proven to be repeatable and smooth. Executing three full-day operations in a week demonstrates our team’s ability to launch at a high cadence going forward. We are very confident in system and operational readiness.


While we didn’t achieve our goal of flight during our first window, we are proud of our team’s execution. The vendor valve issue consumed half our window, and then two marginal propulsion system aborts were safely and quickly resolved. We’ve gained more confidence in our systems engineering, operations capabilities, and readiness – not just to launch RS1 once, but many times over the coming year.



Our next attempt is planned for the first day of our backup launch window, on December 7th. The primary watch item is weather, as December conditions in Kodiak can be challenging both for launch availability and commodity deliveries.


Weather permitting, we look forward to finishing the job.

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