EFT-1 Orion hitting construction milestones – first backshell tile manufactured
Engineers at the Michoud Assembly Facility (MAF) in New Orleans are making good progress with the construction of the Orion spacecraft tasked with the Exploration Flight Test in 2014 (EFT-1). Construction of the Back Bone panels for the Crew Module was completed around the same time as the first tile was manufactured for the vehicle’s backshell.
The uncrewed flight of Orion – otherwise known as the Multi-Purpose Crew Vehicle (MPCV) – will be NASA’s first real step towards transitioning back to Beyond Earth Orbit (BEO) exploration, allowing the spacecraft – that will carry NASA astronauts to destinations as far away as Mars – to stretch its legs for what is a critical test.
Although this mission will be years before a crew ingress Orion ahead of a flight into deep space, the test will provide valuable early data, which can be fed into Orion’s development, thus avoiding any “late” changes to the vehicle that could cause schedule impacts
Because Orion’s launch vehicle of choice – the Space Launch System (SLS) – won’t be available for the EFT-1 mission, a Delta IV-H has been purchased for the role of lofting Orion into space, with the EELV’s Upper Stage providing the second leg of sending the spacecraft into an orbital path that will mimic the vehicle’s return from a deep space mission.
The mission – involving two orbits to a high-apogee, with a high-energy re-entry through Earth’s atmosphere on what is a multi-hour test – will provide critical re-entry flight performance data and demonstrate early integration capabilities of the spacecraft.
“The entry part of the test will produce data needed to develop a spacecraft capable of surviving speeds greater than 20,000 mph and safely return astronauts from beyond Earth orbit,” noted Associate Administrator for Human Exploration and Operations Bill Gerstenmaier.
“This test is very important to the detailed design process in terms of the data we expect to receive.”
The Spring, 2014 launch date – which has slipped from 2013 – is still within the EFT-1 schedule milestones that will allow the data to be fed into Orion’s Critical Design Review (CDR), which is currently set for April, 2015.
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As noted by Mr Gerstenmaier, a lot of emphasis is being placed on the critical element of any spacecraft returning from space – the heatshield.
Unlike the Space Shuttle orbiters, the main business end of the heatshield – the blunt end of Orion – won’t be covered in tiles, instead it will use an ablative material, which was also used on the Apollo capsules.
NASA’s Orion Thermal Protection System Advanced Development Project considered eight different candidate materials, before downselecting to an Avcoat and Phenolic Impregnated Carbon Ablator – with a technical name of AVCO 5026-39 HCG (Filled Epoxy Novalac in Fiberglass-Phenolic Honeycomb).
The backshell, however, will have several hundred tiles, exotically named as TUFI coated AETB-8 tiles, bonded to 10 panels of composite laminate facesheets on a titanium honeycomb core.
As noted on L2’s EFT-1 Update Section, the first of these tiles has been manufactured, which source information claiming this historic milestone began with Tile 875-1 on Panel H of the backshell – as seen in this photo acquired by L2 in the EFT-1 Update Section.
Originally, the baseline for the backshell was a SLA-561V material with plasma sprayed aluminum coating for on-orbit thermal control. However, the AETB-8 tiles provide more mass-efficient MMOD (Micro-Meteoroid Orbital Debris) protection.
As such, panel tile thickness, substrate facesheet thickness, and core density are tailored for thermal and structural load, and MMOD requirements.
The tiles will be mechanically attached to the pressure vessel with thermal isolating brackets along their edges, a process which has already been practised on an entire C panel for the Orion Ground Test Article (GTA).
It is understood the backshell will also sport several tiles covered with a Catalytic Coating (CC), which has already enjoyed valuable entry data during shuttle Discovery” final missions, which included a Catalytic Coating applied to two tiles in the turbulent heating wedge on the belly of the orbiter, appearing as two green stripes across the tiles.
A version of the coating was first flown on STS-2, 3 and 5, as part of a laminar/catalytic flight test effort. However, the documentation wasn’t maintained, leading to the Orion request for help from the flagship orbiter.
Several Detailed Test Objectives (DTOs) into understanding the entry heating performance of a fully catalytic (CC-2) coated tile located downstream of an in-built protuberance – designed for Mach 18 Boundary Layer Transition – were achieved by Discovery during the last few years of her service.
Meanwhile, the frame of EFT-1 Orion is now taking shape, following the first welds – marking the start of construction efforts on the spacecraft – were completed in September of 2011, using an innovative new friction stir welding process, developed especially for Orion construction.
Another milestone was reached in November of last year, when a successful weld of the Hatch Door Panel to Longeron #6 was completed, followed by the weld of Cone Panel D to Longeron #4.
According to an Orion Status Update presentation, acquired by L2 (Link to Presentation), the fit checks, laser alignment and assembly of the Back Bone panels, brackets and fasteners for the EFT-1 Crew Module (CM) were completed at the start of February – as seen in this photo acquired by L2’s Orion Update Section – a milestone which was cited as on time in the construction timeline.
The vehicle will continue its construction – which is currently at the 75 percent mark from a structural standpoint – at the Michoud Assembly Facility for the remainder of this year, prior to heading to KSC for outfitting work.
(Images: Via L2 and NASA). L2’s Orion and Future Spacecraft specific L2 section includes, presentations, videos, graphics and internal updates on Orion and other future spacecraft.
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