Says Poor Oversight, Execution Doomed Orbital Rendezvous Project

A NASA report released Monday summarizing what led to the failure of last year's Demonstration of Autonomous Rendezvous Technology project (DART) lists a series of problems, ranging from design and technical glitches, to outright failure by the agency to provide adequate oversight of the project.

Investigators state the project -- which was meant to show that a computer-controlled spacecraft could meet a target in orbit and operate in close proximity to it -- was doomed by a variety of issues, that boil down to mistakes made by contractor Orbital Sciences, that designed and built the unmanned spacecraft, and lax oversight by NASA team leaders.

"In effect, it was like, not a smoking gun, but the parts that made up the gun," lead investigator Scott Croomes said, quoted in Florida Today, "any one of which, had it not been there -- had the trigger not been there, had the hammer or the bullet not been there -- the gun could not have fired."

As was reported by Aero-News, during DART's proximity operations near the target -- an out-of-service communications satellite -- the spacecraft began using more propellant than expected. Approximately 11 hours into the mission, the craft detected its propellant supply was depleted and began a series of maneuvers for departure and retirement.

NASA also revealed in the summary that DART also made contact the rendezvous satellite, and boosted its orbit 1.2 nautical miles higher. The rendezvous satellite was not damaged in the encounter.

The report -- which, as per an earlier NASA statement, does not disclose any sensitive information that would be subject to export controls -- says failure of the spacecraft's GPS system to give accurate navigational readings snowballed into larger errors that repeatedly caused the spacecraft's software to reset. In an attempt to compensate for the errors, NASA stated the spacecraft fired its thrusters at such a rate that ate up the spacecraft's fuel supply.

The spacecraft also failed to switch to an onboard guidance program that would have prevented the collision, according to the NASA report.

Those glitches, NASA maintains, were caused by a series of problems during the spacecraft's design and construction phase, including:

• An inexperienced design team at Orbital Sciences, who NASA says turned down expert advice and failed to conduct proper design reviews and testing
• NASA did not provide adequate oversight of the project, and its mission requirements were too broad
• Inadequate documentation of software development, and systems engineering not up to the tasks set by NASA
• Scheduling pressures that contributed to mission problems

An additional factor in the project's failure, according to Croomes, is that the $110 mission began as a low-priority test of orbital rendezvous systems. Such low-priority projects, said Croomes, "get a low classification that does not require as much rigor, does not require as much investment in terms of oversight and efforts to try to be absolutely sure it will work."

However, as NASA's goals shifted in light of a renewed focus on exploration missions, DART became a higher priority -- but did not have the resources to back it up.

Both satellites are now in low-Earth orbits that will not be a hazard to other spacecraft. They will eventually burn up upon re-entry into the Earth's atmosphere.

FMI: Read The NASA Investigation Summary (pdf)