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Anomaly Anomaly / Gilmour Space Technologies

Investigation identifies oxidiser-pump electrical and thermal failures behind Eris maiden-flight loss

The investigation established that two of Eris's four first-stage hybrid motors suffered thrust losses during the July 2025 flight. The first malfunction occurred approximately nine seconds after ignition and another appeared around 17 seconds. Both failures originated in the oxidiser pump subsystem, with electrical and thermal faults identified in motors and inverters. Gilmour said design, qualification and process improvements were being evaluated and implemented, and submitted its final report to Australian regulators.

Why it matters

The identification of specific failure modes provides a concrete engineering basis for corrective action. The upgraded Sirius engine firing in August 2026 subsequently provided an important validation milestone, although integrated flight performance remains unproven.

The numbers

First stage engines
4 engines

One of the four first-stage hybrid rocket motors experienced a loss of thrust.

Source
First failure
9 s

Approximately nine seconds after ignition, one of the four first-stage hybrid rocket motors experienced a loss of thrust.

Source
Second failure
17 s

A second motor exhibited similar behaviour at around 17 seconds.

Source

Coverage

1 report

  1. Gilmour Space ·

    Update on Eris TestFlight1 Investigation

    Gilmour Space published the findings of its investigation into the failed Eris TestFlight1 mission of 30 July 2025. One of the four first-stage hybrid engines lost thrust approximately nine seconds after ignition, followed by a similar problem in another engine around 17 seconds. Investigators identified two independent failure modes involving electrical and thermal faults in the oxidiser pump subsystem, including electric motors and associated inverters. A final report was submitted to the Australian Space Agency and Office of the Space Regulator.

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AI-assisted summary of 1 report; numbers link to their source. Spot an error? Tell us.

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The investigation established that two of Eris's four first-stage hybrid motors suffered thrust loss

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