SpaceX Dragon
April 16, 2014

SpaceX Launch Scheduled For April 18

redOrbit Staff & Wire Reports - Your Universe Online

UPDATE: April 16, 2014 (11:20AM CDT)

The International Space Station Program and SpaceX have selected Friday, April 18 for the next launch attempt for the Falcon 9 rocket to send the Dragon cargo craft on the company's third commercial resupply mission to the space station. Launch is scheduled for 3:25 p.m. EDT. NASA TV coverage will begin at 2:15 p.m.

A launch on Friday results in a rendezvous with the space station on Sunday, April 20 and a grapple at 7:14 a.m. NASA TV coverage will begin at 5:45 a.m. with berthing coverage beginning at 9:30 a.m.

The U.S. Air Force 45th Weather Squadron forecast predicts a 40 percent chance of favorable weather, with a chance of showers and thunderstorms that could result in violating the Thick Cloud, Lightning and Flight Through Precipitation rules.

SpaceX has settled on a backup launch date of Saturday, April 19 for the best pair of launch dates for the science payloads being delivered to the station. If needed, a Saturday launch would occur at 3:02 p.m. NASA TV coverage would begin at 2 p.m. This would be a three-day transit to the station instead of two days with grapple on Tuesday, April 22.

If SpaceX launches Friday, a contingency spacewalk to replace a failed multiplexer-demultiplexer will be conducted on Wednesday, April 23. If SpaceX scrubs Friday and attempts to launch Saturday, the contingency spacewalk moves earlier to Sunday, April 20.

UPDATE: April 14, 2014 (3:40PM CDT)

Monday's launch attempt of the SpaceX Dragon cargo craft, loaded with nearly 5,000 pounds of supplies for the International Space Station’s Expedition 39 crew, was scrubbed due to a helium leak on the Falcon 9 first stage. The next launch opportunity would be Friday, April 18 at 3:25 p.m. EDT if the issue can be resolved.

UPDATE: April 14, 2014 (3:45AM CDT)

Despite ongoing problems with a backup computer system on the International Space Station, Monday’s scheduled launch of the SpaceX Falcon 9 rocket and Dragon cargo vehicle will take place as originally planned.

NASA announced Sunday afternoon that the company’s third commercial resupply mission to the ISS would not be delayed due to the technical issues that have been impacting some robotic systems on the orbital laboratory since Friday. That proclamation came following a series of meetings earlier in the day involving flight controllers, engineers and managers, during which it was decided that moving forward with the mission would cause no issues.

“The engineering teams reported to mission managers that the station possesses enough redundancy to allow the SpaceX mission” to depart from Launch Complex 40 at the Cape Canaveral Air Force Station in Florida at 4:58pm EDT on Monday afternoon, the US space agency said.

“In advance of launch, the station’s Mobile Transporter will be moved to the proper position on the truss later today and after Dragon’s launch, the station’s solar arrays will be oriented Monday to the correct angles for the scheduled capture of the US cargo craft on Wednesday and its berthing to the Earth-facing port on the Harmony module,” NASA added. “These are steps that would properly configure the station for the mission even if the prime MDM experiences a problem.”

In addition, NASA personnel have begun preparations for a contingency spacewalk to fix the issue with the computer command relay box. Two members of the Expedition 39 crew will be participating in that extra-vehicular activity (EVA) no sooner than April 22, during which they will replace the failed component (known as a multiplexer demultiplexer or MDM) with a spare that is currently housed within the station.

“Mission managers approved a plan for the preparation of two of the U.S. spacesuits on the station and the replacement of a fan pump separator on one of the suits prior to the spacewalk,” NASA said. That work was set to commence immediately.

ORIGINAL: April 13, 2014 (4:50AM CDT)

NASA has announced that a backup computer system onboard the International Space Station will need to be replaced during a spacewalk, and the ongoing problems with the robotic systems could force a previously scheduled SpaceX cargo mission to be postponed, various media outlets reported Saturday.

According to the Associated Press (AP), the US space agency has not yet set a date for the extra-vehicular activity (EVA) required to fix the technical issues impacting some of the space station’s robotic systems. They confirmed that the primary computer is fine and the crew is not in any danger, but noted that Monday’s resupply mission could be delayed.

“Mission managers agreed on Saturday that a spacewalk was needed to replace the bad computer. But officials want one more day before deciding whether the situation is safe enough in orbit to proceed with Monday's SpaceX launch as planned,” the AP said. “NASA said it would decide on Sunday whether to delay the delivery mission.”

Officials at the US space agency said that preparations for the launch of the SpaceX Dragon cargo craft, currently scheduled for 4:58pm EDT on Monday, would continue – in spite of the Friday failure of the backup computer component affecting the Mobile Transporter rail car on the station’s truss.

In order to discuss the situation, NASA has rescheduled a Sunday morning prelaunch briefing. That briefing will now take place at noon EDT at the Kennedy Space Center in Florida.

The SpaceX cargo ship contains about 4,600 pounds of supplies and equipment, including the legs for Robonaut 2 and various scientific experiments, according to Alan Boyle of NBC News.

The component at the heart of the current problem is known as a multiplexer demultiplexer (MDM), and according to NASA, it is one of over a dozen located on the station’s truss which routes computer commands to several different systems on the ISS. The failure Friday was due to a box called EXT-2, which is a backup unit to a prime component on the S0 truss. It occurred during a routine check to make sure that the device was in good condition.

“A reboost of the station using the ISS Progress 53 thrusters was conducted Saturday as planned and placed the laboratory at the correct altitude for Soyuz crew landing and launch operations in May,” the space agency said in a statement. “Station program officials, flight controllers and teams of engineers are working to determine whether there is any risk to launching the SpaceX cargo craft Monday.”

If the launch is allowed to proceed, the Dragon capsule would arrive at the orbital laboratory on Wednesday, where it would be grappled and berthed to the Earth-facing port of the Harmony module. The Canadarm2 robotic arm, which would be used to capture and secure the vehicle, has not been impacted by the failure of the backup MDM.

“While a final decision on the SpaceX launch is being reviewed, another team of engineers is laying out a timeline for a contingency spacewalk that is required to replace the failed spare MDM,” NASA said. “No date for the spacewalk has been scheduled. Such a spacewalk is one of the so-called ‘Big 12’ spacewalks that station crews train to execute for the loss of a critical component on the complex.”