NASA Postpones SpaceX Dragon Cargo Launch to NET May 3 to Fix Station Power Glitch

The International Space Station photographed by Expedition 56 crew members from a Soyuz spacecraft after undocking on Oct. 4, 2018. Credit: NASA/Roscosmos

Ken Kremer -- SpaceUpClose.com & RocketSTEM – 30 April 2019

TITUSVILLE, FL  –  NASA officials today postponed the planned May 1 launch of a SpaceX Dragon cargomission to the International Space Station (ISS) by at least 48 hours after discovering an electrical power problem caused by a failed power distribution component on the orbiting lab complex yesterday April 29 that must be fixed first to ensure the commercial craft can be berthed successfully. Note: Story updated with further details

NASA asked SpaceX to stand down from Wednesday’s planned overnight liftoff of their Falcon 9 rocket carrying the robotic Dragon CRS-17 spacecraft while engineers work to troubleshoot and resolve the power distribution issue that has impacted the station’s Main Bus Switching Units (MBSU) ability to distribute power to two of the eight power channels on the station after the MBSU 3 unit failed. 

The two channels impacted with lost power from the failed MBSU 3 component were channels 3A and 3B. 

“NASA has requested SpaceX move off from May 1 for the launch of the company’s 17th commercial resupply mission to the International Space Station,” NASA officials announced in a statement released at midday today, April 30.

“The earliest possible launch opportunity is no earlier than Friday, May 3.” 

SpaceX and NASA now targeting 3:11 a.m. EDT (0711 GMT) Friday, May 3 as the earliest possible date for the Falcon 9 rocket launch of the unpiloted Dragon CRS-17 cargo ship from Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida.


NASA emphasized that there was no danger to the station or the six person crew of astronauts and cosmonauts on board at this time. 

“There are no immediate concerns for the crew or the station.”

Multiple sources told Space UpClose yesterday that the launch was very likely to be delayed by at least two days after the power glitch was discovered Monday morning April 29.

Up Close view of prior Dragon CRS-16 cargo ship bolted atop SpaceX Falcon 9 rocket poised for liftoff on mission to the ISS from Space Launch Complex-40 on Cape Canaveral Air Force Station, FL, on Dec. 5, 2018 at 1:16 pm EST. The CRS-17 cargo ship is now slated for liftoff NET May 3, 2019.  Credit: Ken Kremer/kenkremer.com/spaceupclose.com

Engineers on the Flight Investigation Team (FIT) at NASA's Johnson Space Center, Houston, Tx are working diligently to come up with a viable plan to successfully resolve the stations power distribution problem. 

The Main Bus Switching Units (MBSU) purpose is to feed electric power generated by the solar arrays to all stations systems via the eight power channels. 

The MBSUs have failed previously aboard the station and been replaced using the robotic arm - via an operation dubbed Remove and Replace (R & R).

MBSU2 was replaced robotically by ground team operators back in May 2017 for example.

However the robotic arm must have two functioning redundant power sources per station operating rules in case one channel fails during use - such as to grapple the Dragon cargo ship. Hence the launch delay.

“On April 29, the space station team identified an issue with one of the station’s Main Bus Switching Units that distributes power to two of the eight power channels on the station.” 

Thus 2 days is the minimum delay, and no one should be surprised if further delays are necessary as the repair plan is developed as quickly and safely as possible and implemented with a hopefully successful outcome.

Weather forecasters predict 60% chance of acceptable weather at the 3:11 a.m. ET launch time on May 3, down from 80% GO for May 1.

NASA hopes to repair the failed power unit component and restore full power by using the stations Canadian-built Canadarm2 robotic arm rather than sending a team of space walking astronauts outside for the job. 

“Teams are working on a plan to robotically replace the failed unit and restore full power to the station system,” NASA elaborated today.

The Aurora and the night sky above Earth’s atmosphere are pictured from the space station. A portion of the station’s solar arrays and a pair of nitrogen/oxygen recharge system tanks are pictured in the foreground.  Credit: NASA 

NASA initially announced Monday that teams had found a power issue and were troubleshooting to determine root cause as well as determining of the then planned May 1 SpaceX launch would be impacted. 

“Monday morning, teams identified an issue with the International Space Station’s electrical power system and are working to identify the root cause and restore full power to the system,” NASA stated in a blog post Monday, April 29.

“There are no immediate concerns for the crew or the station. An issue is being worked with a Main Bus Switching Unit (MBSU) that distributes electrical power to two of the eight power channels on the station. Flight controllers have been working to route power through the remaining six power channels. Electrical power generated by the station’s solar arrays is fed to all station systems through these power channels. Discussions are underway to determine any impacts to SpaceX’s CRS-17 cargo resupply mission targeted for launch May 1.”

The Dragon CRS-17 cargo freighter will carry over 2.7 tons of science experiments, research gear, crew supplies and hardware to the orbiting laboratory to support the Expedition 59 and 60 crews for the 17th mission under NASA’s Commercial Resupply Services (CRS) contract.

“The Expedition 59 crew will welcome Dragon when it arrives  …. carrying nearly 5,500 pounds of cargo.”


Canadian Astronaut David Saint-Jacques “will be at the controls of the robotics workstation …  commanding the Canadarm2 to capture Dragon” whenever it does arrive.

A launch Friday translates to a Sunday May 5 arrival. 

NASA TV will broadcast the launch and capture activities live.

SpaceX conducts successful daytime static fire test of new Falcon 9 first stage engines at 10 a.m. EDT on April 27 with exhaust wafting overhead at Space Launch Complex-40 on Cape Canaveral Air Force Station for CRS-17 resupply mission to the ISS targeted for launch May 3, 2019 - NASA KSC picturesque Vehicle Assembly Building (VAB) seen nearby at left.  Credit: Ken Kremer/kenkremer.com/spaceupclose.com

The path to the prior May 1 launch was cleared after SpaceX completed a critical and successful static hot fire test of their Falcon 9 rocket first stage engines at 10 a.m. EDT Saturday morning, April 27 for the NASA contracted resupply mission to the International Space Station (ISS).

Check out my exclusive Space UpClose eyewitness photos captured about 13 miles away this morning in Titusville, Fl – with NASAs iconic and picturesque Vehicle Assembly Building (VAB) seen nearby in the scene. 

The mission is also very exciting because it will also feature the 1^st ever droneship landing that should be easily visible occurring just a few miles offshore of the Florida Space Coast beaches – following an emergency approval granted last week by the Federal Communications Commission (FCC). 

This Dragon is refurbished and recycled and previously flew on a prior CRS mission to the station. 

The 20-foot high, 12-foot-diameter Dragon CRS-16 vessel is jam packed with more than 5500 pounds (2500 kilograms) of science experiments, research hardware, space parts, food water, clothing and more supplies for the six person Expedition 59 and 60 crews.

The science payload alone amounts to 1601 pounds, 726 kg  - including the two unpressurized cargo payload carried up in the truck and to be mounted externally:  namely NASA’s Orbiting Carbon Observatory-3 (OCO-3) which will measure levels of carbon dioxide in the atmosphere during its planned 3 year mission and the Space Test Program-Houston 6 (STP-H6).

SpaceX Dragon CRS-17 mission truck carrying two payloads including NASA’s Orbiting Carbon Observatory-3 (OCO-3) and the U.S. military’s Space Test Program-Houston 6 (STP-H6) payloads. Credit: NASA

Watch for Ken’s continuing onsite coverage of NASA, SpaceX, ULA, Boeing, Lockheed Martin, Northrop Grumman and more space and mission reports direct from the Kennedy Space Center, Cape Canaveral Air Force Station, Florida and Wallops Flight Facility, Virginia.

Stay tuned here for Ken's continuing Earth and Planetary science and human spaceflight news: www.kenkremer.com –www.spaceupclose.com – twitter @ken_kremer – email: ken at kenkremer.com

Dr. Kremer is a research scientist and journalist based in the KSC area, active in outreach and interviewed regularly on TV and radio about space topics.
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SpaceX conducts successful daytime static fire test of new Falcon 9 first stage engines at 10 a.m. EDT on April 27 with exhaust wafting overhead at Space Launch Complex-40 on Cape Canaveral Air Force Station for CRS-17 resupply mission to the ISS targeted for launch May 3, 2019 - NASA KSC picturesque Vehicle Assembly Building (VAB) seen nearby at left.  Credit: Ken Kremer/kenkremer.com/spaceupclose.com