NASA is to confirm next week that its Orion crew exploration vehicle's preliminary design review is to slip from November to mid-2009 after the agency delayed its internal planning date for the spacecraft's first flight by a year to September 2014.
Rescheduled once to this November, the PDR will now be replaced by a meeting that will identify key technical issues and start a third design analysis cycle, which had been planned for after the preliminary review.
In early 2006 Orion's PDR had been scheduled for April this year but that has now been delayed by up to 16-months, as the agency has not determined when during the second or third quarters of next year the PDR will take place.
Brian Muirhead, a Jet Propulsion Laboratory systems engineer employed by the Constellation programme for transportation architecture work, told Flight at the AIAA Space 2008 conference on Tuesday 9 September: "I can say definitively that PDR will not happen in November. We are going to go through one more design cycle."
One of the technology difficulties for Orion has been its crew module's heat shield. Originally baselined to be Phenolic Impregnated Carbon Ablator (PICA), that flight proven material is now facing competition from a new version of the Apollo programme's Avcoat thermal protection system (TPS). NASA's interest in Avcoat emerged in May 2007.
With a new formulation that removes certain chemicals, banned by the US government's Environmental Protection Agency since Apollo, Muirhead said ongoing testing at NASA Ames Research Center demonstrated good Avcoat performance and showed that the new version was lighter than the original material.
NASA's CEV Block II heat shield advanced development phase two project had planned the 15 January 2008 for the down select to one TPS material.
Problems with the heat shield began to emerge when the delivery of the manufacturing development unit was delayed by three months, from 2 November 2007 to the end of January this year. The TPS down select decision is now expected as part of the Orion technical discussions in November.