A thrust vector activator issue Tuesday scrubbed a Space Exploration Technologies Corp. (SpaceX) launch for the second time in just over six months.
The company was scheduled Tuesday to begin its fifth Cargo Resupply Services (CRS-5) mission for NASA, but canceled at the last minute. SpaceX said on its website that engineers observed drift on one of the two thrust vector actuators on the second stage of the Falcon 9 rocket during the terminal count. The company said this would have “likely” caused an automatic abort.
SpaceX founder and CEO Elon Musk said on Twitter the company needed to investigate the “upper stage Z” actuator as it was “behaving strangely.” A NASA statement on the civil space agency’s blog Tuesday said the issue will need to be resolved before Friday’s launch. SpaceX’s second attempt to deliver cargo and supplies to the International Space Station (ISS) is scheduled for Friday at 5:09 a.m. EST from Cape Canaveral Air Force Station, Fla.
The thrust vector control actuator on a Falcon 9 first stage scrubbed SpaceX’s Orbcomm [ORBC] OG2 mission last June. SpaceX President and COO Gwynne Shotwell said in June the company could have flown through it for the Orbcomm mission, but wanted to be “super careful” while checking the second stage actuator (Defense Daily, June 30).
SpaceX did not provide responses to questions in time for Wednesday’s edition. For June’s Orbcomm mission, it used actuators designed by JASC to control the thrust vector angle on Falcon 9 first- and second-stage engines. JASC said on its website its actuators are designed for high vibration and shock loads and has excellent frequency response characteristics. They were also designed for short-term immersion in salt water.
A number of companies make thrust vector actuators for use in rockets. In addition to JASC, Honeywell [HON], Woodward [WWD] and Moog [MOG] also make actuators. Moog spokeswoman Andrea Barone said Tuesday the company doesn’t supply thrust vector actuators to SpaceX. Moog supplies centaur electromechanical thrust vector control actuation systems to United Launch Alliance (ULA) for the company’s Atlas V 541-configuration second stage, according to a company statement.
Tuesday’s launch scrub was also significant as SpaceX was to attempt to land its Falcon 9 first stage on a surface other than water for its first time. The company designed an unanchored floating barge, repurposed from deep sea oil rigs, with a maximum of 51,000 square feet of surface. SpaceX, calling this barge an autonomous spaceport drone ship, said thrusters on the barge could hold position within three meters, even in a storm. The company said the legspan of the Falcon 9 first stage is about 21 meters, and for this first attempt, was aiming for a landing accuracy of within 10 meters.
To enable accuracy, SpaceX added four hypersonic grid fins placed in an “x-wing” configuration around the Falcon 9, stowed on ascent and deployed on reentry to control the first stage’s lift vector. Each fin moves independently for roll, pitch and yaw, and combined with the engine gimbaling, is to allow for precision landing. SpaceX previously “soft landed” the Falcon 9 first stage into the ocean after previous launches as part of its long-term goal of creating a reusable launch vehicle.
ULA is a joint venture of Lockheed Martin [LMT] and Boeing [BA].