On 30 October 2001, the University of Queensland Department of Mechanical Engineering (UQ), launched an experimental supersonic-combustion ram jet (scramjet) payload via a two-stage solid-fuel rocket that was provided by Astrotech Space Operations Inc (Astrotech). The rocket was launched from the Woomera Prohibited Area in northern South Australia, that was operated by the Department of Defence (DoD). The planned flight was to validate data obtained in the hypersonic wind tunnel at the UQ facilities.
The launch occurred at 1301 Australian Central Summer Time and according to observers and video evidence, the first stage booster appeared to operate successfully, although UQ personnel noted an anomaly in the received telemetry data. After the initial coast stage, during which time the first stage separated, the second stage ignited and observers reported seeing the rocket and the resultant exhaust trails appearing to curl in a 'cork screw' fashion. That continued with the stability of the rocket appearing to deteriorate until it was out of sight.
The first stage (Terrier) was recovered from the intended impact area shortly after the flight, while remnants of the first stage fixed fins were recovered north east of the flight path and between the first stage impact area and the launch pad approximately 12 weeks after the launch. The separate location of the fins indicated that the fins separated from the vehicle during the first stage flight.
The second stage (Orion) with fixed fins and payload was recovered about 16 weeks after the launch from an area about 28 km east of the Stuart Highway and about 100 km north west from the launch site rather than the 373 km nominal aiming point. The highway had not been closed to traffic, nor was it required to be.
After the flight, the UQ team reported that while examining their telemetry data they noted an anomaly in the accelerometer and magnetometer data at approximately 2.8 seconds after first stage ignition. UQ also noted that the vehicle had not achieved the spin rate (4-6Hz) that was intended. However, the UQ team suggested that the low spin rate was more likely the result of some other event, perhaps the loss of one or more fins, rather than contributing to the accident. Additionally, a number of personnel who viewed the post-flight video reported seeing what appeared to be objects falling from the vehicle during the first stage burn. However, the Optical Coordinator from the launch team and Australian Transport Safety Bureau (ATSB) investigators considered that the video images lacked sufficient resolution to determine what occurred at those times.
ATSB specialist examination of the first stage indicated that the fixed fin support structure had broken up during the flight. Examination of the fracture surfaces indicated overload through the fixed fin spindle (journal) sockets. Larger Nike fins had been fitted by Astrotech rather than the smaller standard Terrier fins. This was to achieve the required stability and ensure a stable platform during the scramjet experiment. No pre-existing defects were found within the physical structure of the fin support. Some of the fin journal sockets showed evidence of excessive angular bending forces, suggesting possible movement or rotation of the fins during flight. A considerable proportion of the first stage fixed fin skin and internal honeycomb material had not been recovered at the time the investigation was carried out. Of the material that was recovered, most of the damage and deformation suggested both aerodynamic and ground impact forces.
The Nike fixed fin angle of incidence was adjusted using trailing edge adjustment lugs. Marks and damage around the fixed fin adjustment lug mounting points indicated in-flight movement and possible insecurity of the fin adjustment lugs. Crushing damage of the fin rib sections beneath the lug mounting set-screws was possibly pre-flight damage which may have contributed to in-flight movement. It was also noted that the Nike fins were not designed for securing in the location used and contained no reinforcement or other strengthening features in this area. The Nike fins were designed to be secured on the leading side of the fin base, whereas the original Terrier fins were designed to be secured on the trailing side of the fin base.
ATSB specialist examination of the payload found no evidence to suggest that the payload or associated components had contributed to the flight anomaly, however the level of impact damage limited the examination.
During launch preparation, sandbags were placed around the base of the launcher. The Astrotech "Operation and Inspection Log for the Assembly of the Terrier-Orion Suborbital Launch vehicle system" called for grout to be placed at the base of the launcher. However, grout was not available, thus sandbags were used to protect the base of the launcher. UQ suggested that it was possible that a sandbag or a rock in a sandbag could have damaged a fin during the initial launch phase. That would have required a sandbag or rock to have been deflected off the infrastructure and impact a fin. Video footage and still images viewed by the ATSB Specialists and Astrotech, indicated that a number of the sandbags were ejected and/or disrupted during the ignition and launch. However, it was not possible to determine if a rock had impacted a fin during the launch sequence.
The examination could not conclusively determine what caused or allowed the first stage Nike fixed fins to move during the flight. However, based on the available evidence, it is likely that the first stage Nike fins either sustained damage from aerodynamic overload due to their movement during the flight or the fin support structure was unable to support the increased aerodynamic load of the larger Nike fins. It is also possible that the sandbags or rocks ejected during the launch damaged the first stage fixed fins. As a result, at separation, the second stage would have been in an unstable flight attitude and possibly not able to recover stabilised flight.
Because the Space Activities Act and Space Activities Regulations did not provide for a launch licensing instrument with a fee structure appropriate to the resources of educational/scientific organisations, UQ was granted an exemption certificate by the then Minister following a recommendation from the Australian regulator, the Space Licensing and Safety Office (SLASO). As part of UQ's application for an exemption certificate, it was required to furnish a risk hazard analysis of the project based on statutory methodology and informal guidance provided by SLASO.
The investigation determined that although the risk analysis conducted by UQ allowed for failure of the first stage and non ignition of the second stage, insufficient allowance was made for the rocket vehicle malfunctioning and going off course. During the investigation, UQ indicated that as part of its hazard identification during the risk hazard analysis process, it had not specifically considered the possibility of the rocket impacting near the Stuart Highway. The second stage and payload impacted about 28 kilometres east of the highway.
Although SLASO had expressed reservations in an internal document, prior to the launch, regarding the risk hazard analysis submitted by UQ, it assessed the analysis as part of the application and recommended that UQ be granted the exemption certificate. SLASO was satisfied that a risk hazard analysis has been performed and that the launch would comply with the Launch Safety Standards of the Flight Safety Code , provided there were adequate exclusion arrangements for the WIR and the area around the nominal aiming point. As part of that assessment, SLASO also relied, in part, on the granting of a licence to Astrotech by the United States regulator, the Federal Aviation Administration (FAA), the submission of a risk hazard analysis to the FAA by Astrotech as part of their launch licence application and an analysis conducted by the FAA. Although SLASO requested a copy of that analysis from the US regulator, it was not provided. After the Launch, SLASO commented that there was no evidence that the launch violated the risk acceptance criterion spelled out in the launch safety standards of the Flight Safety Code.
SLASO is seeking to acquire specialist risk analysis software, with appropriate user training, to assist with assessing risk hazard analysis models submitted by applicants. SLASO also indicated that it plans to provide additional guidance for applicants wishing to apply for a licence, permit or exemption certificate. Additionally, Government approval has been granted to amend the Space Activities Act to provide for educational/research activities with an appropriate fee structure. That will allow the requirements to be clearly spelt out in regulations made in respect of that certificate.
UQ has indicated that it intends to reassess its risk hazard analysis.
Astrotech indicated that it plans to review its pre-launch assembly procedures of the rocket vehicle.
DoD has indicated that it plans to review its internal procedures for the approval of Woomera Prohibited Area activities and that the MoU with SLASO may also be reviewed.
In addition to these safety actions, the Investigator issues the following recommendations.
1) That Astrotech review the:
a) suitability of the Nike fins for use on the Terrier vehicle;
b) suitability of the fin support attachment structure when other than Terrier fins are used;
c) suitability and effectiveness of the opposing set-screw arrangement for securing and setting the Nike fin incidence angle to the Terrier fin support structure; and
d) suitability of the use of sandbags at the base of the launcher pedestal, in lieu of the specified grouting.
2) That SLASO require all Australian launch operators to submit a comprehensive risk hazard analysis for independent verification prior to the issuing of a licence, permit or exemption certificate.
3) That SLASO consider requiring launch operators to submit their risk hazard analysis to stakeholders and participants, for review and discussion.
4) That launch infrastructure providers make available sufficient resources to enable the provision of appropriate recording equipment with suitably trained personnel to provide additional recorded evidence to aid any occurrence investigation that may be necessary.
5) That overseas organisations involved in an Australian launch provide any risk hazard analysis and/or assessment to SLASO to better enable SLASO to properly assess a launch application.
|Type:||Research and Analysis Report|
|Publication date:||18 June 2002|
|ISBN:||0642 7 2210 2|