Wednesday, 19 May 2021

SBIRS GEO 5 Centaur fuel blowout imaged from Australia

click to enlarge

On 18 May 2021 at 17:37 UT, the United Launch Alliance (ULA) successfully launched SBIRS GEO 5 for the US Space Force from Cape Canaveral, using an Atlas V rocket. SBIRS GEO 5 is an Early Warning satellite that detects missile launches (SBIRS = Space-Based Infra-Red System). It was placed in a geosynchronous orbit. Two other small rideshare payloads were also launched on this launch.

Looking at the mission profile, I realized that the fuel blowout of the Centaur upper stage from the launch would be visible from Australia and Indonesia. So I alerted the Seesat-list and also sent a private alert to Paul Camilleri, an observer in Australia who in the past has made spectacular imagery of such Centaur fuel blowout events.

Paul grabbed his camera and went out. And returned with spectacular imagery, which I show here with his kind permission. According to Paul, the blow-out cloud reached magnitude +3.

Paul made his imagery with a Nikon D3200 with an F2.0/85 mm lens. They are 5-second exposures (fixed tripod) at ISO 6400.

In the first image shown, taken 18:55 UT just before start of the blowout sequence, you can see both the Centaur upper stage and the SBIRS GEO 5 payload, which had separated from the Centaur some 40 minutes earlier. In the second image shown, taken 5 minutes later, you can see a V-shaped fuel cloud and a circular ring of blown-out fuel. In the other images, you see further venting, creating a bright V-shaped cloud that slowly dissipated over the next tens of minutes. Paul imaged it untill 19:40 UT.


Click images to enlarge


Paul was not the only one imaging the fuel blowout. Australian astronomer Robert McNaught also captured the event on his all sky camera (image used with permission):



The fuel blowout happened at about 12000 km altitude. The Centaur upper stage was over the eastern Indian Ocean, just northwest of the West Australian coast at that moment (see map below).

click map to enlarge

Fuel blow-outs are done to get rid of left-over rocket fuels in the rocket stage. Venting them into space reduces the risk that vapours from the left-over fuel might ignite (e.g. because of static electricity buildup in the rocket stage) and cause a debris-generating explosion.


Animated image sequence by Grahame Kelaher from Australia:


Animated image sequence by Tel Lekatsas, also from Australia:

A movie from the all-sky camera of the Edward Pigot Seismic Observatory, courtesy of Michael Andre Phillips in Australia is here (look at the right of the image in the gap in the trees)

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