Additional countdown hold for Shuttle Discovery

by Chris Bergin

A NASA executive decision has officially added the option of an additional hold being called – with one minute remaining in the countdown – to avoid the bird strike risk observed just seconds into the launch of Shuttle Discovery on STS-114 last year.

Implemented into STS-121’s Terminal Countdown, the Launch Director at KSC now has the power to halt Discovery’s countdown at a new hold point of T-60 seconds, if there’s a threat of a bird strike.

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The ‘Closure of INEV-01 (Natural Environments) Integrated Hazard Report’ was initiated due to the bird strike on the External Tank during STS-114, just seconds into lift-off. Due to that event, managers have noted that the likelihood of similar event has increased from ‘remote to infrequent,’ as part of their IFA (In Flight Anomaly) report.

STS-114’s bird strike – now identified as a Vulture – was caught on video, which showed one bird of a small flock crashing into the top of the External Tank, before falling down the Shuttle to its unpleasant death. **VIDEO OF THE BIRD STRIKE**

‘STS-114 sustained a low-speed bird strike at lift-off. Before it had cleared the Pad 39B umbilical tower, the SSV (Space Shuttle Vehicle) struck what was later identified as a Vulture, which impacted the external tank ogive and fell on the -Z side of the ET,’ noted the document. ‘It was vaporized by the SRB plumes.

‘Two other large birds were seen flying over the SSV and are presumed to have also been vaporized. As a result of this bird strike, an In-Flight Anomaly (IFA), IFA-114-I-13 Bird Strike During Ascent, was initiated.’

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While the document claims the Launch Director will make the ‘decision to hold or continue countdown at T-1 min. based on bird activity near pad,’ sources note that this will be a new hold point in the countdown, as opposed to running to T-31 seconds and then holding, ahead of Auto Sequence Start.

The ability to hold at T-1 minute is very limited after the start of LOX drainback which occurs at T- 4:55. This hold time is typically three to four minutes long before a scrub has to be called.

The raising of the likelihood of a problem with bird activity interfering with the launch is – according to the document – ‘based on limited effectiveness of tools to detect birds near launch pad. Limited experience with detection tools.’

While a re-evaluation will take place prior to STS-115 with Atlantis, the ‘consequence remains CATASTROPHIC,’ yet also ‘remains (an) ACCEPTED RISK. Overall Hazard Report classification remains ACCEPTED RISK.’

Measures have already been put in place to mitigate the potential issue, with sound deterrents and vulture traps planned for STS-121, plus the recent Carrion removal program implemented at KSC. Bird radar and cameras are also planned to be used to monitor birds.

Other measures include ‘Terror Eyes’ scary balloons on the pad, visual monitoring, Vulture traps water hoses, predatory bird calls, loud noises and bird cannons.

‘The Launch Director makes a decision within the last minute of the countdown whether to continue the count based on an assessment of the bird activity near the vehicle to mitigate the risk of invasive fauna. This new procedure serves to reduce the risk of striking a bird during launch,’ noted an adjoined report from Boeing and the United Space Alliance.

‘Several mitigation techniques, including sound deterrents and vulture traps are planned for implementation for STS-121. Additionally, a carrion (road kill) removal program has been implemented to reduce the vulture population at KSC. The goal of this program is to remove any animal carcasses from the roads within one day.

‘U.S Fish and Wildlife Service at Merritt Island National Wildlife Refuge believes that such a reduction in the available food source will result in a reduction in the resident vulture population.’

STS-121 is due to launch next month in a window that may possibly be pushed back slightly to a NET (No Earlier Than) July 2 or 3 due to lighting constraints on ET debris imaging *article to follow based on a large outline document now published on L2*

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