Orion EFT-1 Launch Scrubbed, May Try Again Tomorrow – UPDATE

Orion EFT-1 Launch Scrubbed, May Try Again Tomorrow – UPDATE

This article is updated throughout following a post-scrub press conference at Kennedy Space Center.

NASA’s attempt to launch the Orion Exploration Flight Test-1 (EFT-1) mission this morning (December 4) was scrubbed due to weather and technical issues. NASA, Lockheed Martin and the United Launch Alliance (ULA) plan to try again tomorrow, although they are still looking at weather and technical issues.  If the launch proceeds tomorrow, the launch window is the same (7:05 – 9:44 am EST).  The weather forecast has deteriorated and now is only 40 percent favorable.

Today’s 2 hour 37 minute launch window opened at 7:05 am EST.  Launch was initially delayed for a few minutes because a boat entered restricted waters off Cape Canaveral.  Then two launch attempts were scrubbed because automated sensors detected wind gusts exceeding the 21 knot limit for northerly winds and halted the countdown.  Then technical issues arose with the fill and drain valves for the Delta IV Heavy’s three core boosters (the three orange cylindrical tanks in the photo below).

United Launch Alliance (ULA) Delta IV Heavy launch vehicle for NASA’s Orion EFT-1 mission.   Photo credit:  ULA

Each of the three core boosters is fueled by liquid hydrogen (LH2) and liquid oxygen (LOX).  There are LH2 and LOX fill and drain valves for each booster – a total of six.   Although initial reports indicated that two of the LOX valves did not close and later that it was LH2 valves causing the problems, ULA’s Dan Collins said at the post-scrub press conference that all the LOX valves operated perfectly; only the LH2 valves were problematical.   Troubleshooting efforts did not solve the problem before the launch window closed, and ULA continues to assess the issue. 

Collins, who is ULA’s Chief Operating Officer, said he is confident the valves will be ready for tomorrow, however.  He said ULA encountered this in a previous Delta IV Heavy launch and believes it is related to the valves getting too cold during long countdowns.  LH2 is -423 degrees F (-253 degrees C). 

The launch is being conducted by Lockheed Martin and ULA, not NASA (which is buying the resulting data from Lockheed Martin).  While ULA was assessing weather and valves, Lockheed Martin was looking at how many times it could cycle the Orion spacecraft on and off and still conserve enough battery power for the rest of the mission. Orion uses external power until a certain point in the countdown (T-9 minutes) when it switches to internal power and begins drawing on its battery resources.  That happened this morning each time the countdown passed that mark.  Lockheed Martin Orion program manager Mike Hawes added that there are additional issues regarding how much data can be stored, so there are a finite number of times the countdown can be stopped and started from the Orion perspective.

As of the time of the post-scrub press conference at noon EST, the plan is to try again tomorrow, December 5.   However, Collins explained that the Delta IV can launch two of any three days in a row because of fueling constraints.  If they try again tomorrow and there is another scrub, they would not be able to try on Saturday.  Sunday would be the earliest date to reschedule.  Right now they only have permission to use the Eastern Test Range (of which Cape Canaveral Air Force Station is part) today, tomorrow and Saturday.  They will continue to assess the technical issues with the Delta IV, the Orion recycle issues, and the weather outlook before they fuel the vehicle in case they decide to wait until Saturday.  

The weather forecast for tomorrow has deteriorated to only 40 percent favorable (it had been 60 percent).  On Saturday it is 70 percent favorable.  The concern about wind speed and direction is because the wind can push the Delta IV — as massive as it is — once it lifts off and it could hit into surrounding structures near the launch pad.

When it does launch, the EFT-1 mission will last just 4.5 hours as Orion makes two orbits of the Earth and then reenters through the atmosphere at high speed to test its heat shield, splashing down in the Pacific off the coast of Baja California.

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