# Eris by Gilmour Space Technologies

Canonical page: https://technooptimist.io/spaceflight/eris
Frontier: [Spaceflight](https://technooptimist.io/spaceflight.md) · Field: Small rockets · Company: [Gilmour Space Technologies](https://technooptimist.io/companies/gilmour-space.md)
Stage: Proto (2 of 5: Research → Proto → Pilot → Deploy → Scaling)
Updated: last update 2026-03-26, facts checked 2026-10-11
Goal: Give Australia its own way into orbit, launching small satellites from home soil instead of buying rides abroad, using cheaper, simpler hybrid rocket motors.
Status: First flight fell back after 14 s in July 2025; TestFlight 2 targeted end 2026 to early 2027.
Next milestone: TestFlight 2 orbital attempt, target Q1 2027 (slipped 12 months; originally Q1 2026)

## Milestones

| Status | Milestone | Date | Slip |
| --- | --- | --- | --- |
| Done | Bowen becomes Australia's first commercial orbital spaceport | 5 Mar 2024 |   |
| Done | Australian Space Agency grants the Eris launch permit | Nov 2024 |   |
| Done | Aviation regulator CASA approval | 19 Feb 2025 |   |
| Done | TestFlight 1 lifts off, falls back after 14 seconds | 30 Jul 2025 | +14 mo (originally May 2024) |
| Planned | Suborbital hypersonic test flight | 2026 |   |
| Current | TestFlight 2 orbital attempt | Q1 2027 | +12 mo (originally Q1 2026) |

## Upcoming events

- **2026**: Suborbital hypersonic test flight
- **Q1 2027**: TestFlight 2 orbital attempt (slipped 12 mo)

## Most important updates

- **26 Mar 2026**: Gilmour targets end of 2026 for Eris TestFlight 2, after a suborbital hypersonic test. Gilmour Space said it was looking at the end of 2026 for its second orbital attempt. ([our story](https://technooptimist.io/stories/gilmour-targets-end-of-2026-for-eris-testflight-2-after-a-suborbital-6da31eaf.md) · [original source](https://www.spaceconnectonline.com.au/launch/7019-gilmour-confirms-expectation-to-conduct-second-test-flight-in-late-2026))
- **30 Jul 2025**: Gilmour's Eris, the first Australian-built orbital rocket, falls back 14 seconds after liftoff. Eris lifted off from the Bowen Orbital Spaceport in North Queensland, arced away from the pad, drifted sideways and came down in an uncontrolled touchdown after 14 seconds. ([our story](https://technooptimist.io/stories/gilmour-s-eris-the-first-australian-built-orbital-rocket-falls-back-14-91dc947a.md) · [original source](https://www.astronomy.com/space-exploration/gilmour-testflight1-fails-with-sideways-hop/))

## Current obstacles

- **First flight failed early**: TestFlight 1 cleared the tower but drifted sideways and fell after 14 s; the investigation is complete but findings are not published.
- **Long delays**: First launch slipped about 14 months from May 2024 on technical problems, permits and winds; flight 2 has slipped from early 2026.

## Physics limits

- **Hybrids burn less efficiently**: Fuel only burns where it meets the oxidiser at the grain surface, so mixing is uneven and efficiency is lower than good liquid engines, costing payload.
- **Big hybrids are hard to scale**: The burning surface grows slowly, so large hybrids need long or multi-port grains to make enough thrust, which can leave unburnt fuel and shake the motor.

## How it works

### Hybrid: A solid fuel grain and a liquid oxidiser

Liquid oxidiser is sprayed down a hollow solid-fuel core and burns along its walls; cutting the oxidiser flow throttles or stops the motor.

### Safer to handle: Fuel and oxidiser kept apart

Fuel and oxidiser are stored apart and in different states, so hybrids are safer to handle than solid motors and simpler than liquid engines.

### Three stages: Hybrids below, liquid on top

Four Sirius hybrids lift the first stage, one powers the second, and the liquid Phoenix engine finishes the climb to orbit.

## Spec sheet

| Spec | Eris | Provenance |
| --- | --- | --- |
| Payload to low orbit | Up to 300 kg | reported |
| Stages | 3 | reported |
| First stage | 4 Sirius hybrid motors | reported |
| Third stage | Phoenix liquid engine | reported |
| Height | 23–25 m (reports differ) | reported |
| Mass at liftoff | About 30 t | reported |
| TestFlight 1 flight time | 14 s | reported |

Provenance: reported = stated by the company; estimated = our estimate; sample = a sample figure.

## About Gilmour Space Technologies

Queensland company building Eris, the first Australian-designed orbital rocket, and running Australia's first commercial orbital spaceport at Bowen. Founded by brothers Adam and James Gilmour.

- Eris made Australia's first orbital launch attempt in over 50 years on 30 July 2025; it fell after 14 seconds.
- Uses hybrid rocket motors (solid fuel, liquid oxidiser) on its first two stages.
- Next orbital attempt, TestFlight 2, targeted for end 2026 to early 2027.

- Headquarters: AU
- Status: private
- Website: https://gspace.com
- People: Adam Gilmour (CEO and co-founder); James Gilmour (Co-founder)
- Partners, customers, investors: Australian Space Agency (partner); Blackbird Ventures (investor); Main Sequence Ventures (investor)

Company page: https://technooptimist.io/companies/gilmour-space.md

## Related programs

Everything in Spaceflight: https://technooptimist.io/spaceflight.md

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