Says Poor Oversight, Execution Doomed Orbital Rendezvous
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
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
The spacecraft also failed to switch to an onboard guidance
program that would have prevented the collision, according to the
Those glitches, NASA maintains, were caused by a series of
problems during the spacecraft's design and construction phase,
- 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.