The International Space Station is currently home to six intrepid astronauts, one Robonaut, and four 14,000-pound payload-holders called ExPRESS Logistics Carriers. Experiments from Earth like the laser-communicator OPALS fly up to Station and Lego-attach to these carriers, which provide them with a place to stay and, just as importantly, the electrical power and data links they need to do their jobs. But since 2013, scientists sending up payloads have had trouble with the on-orbit utility grid.

Right now, experiments need special power converters if they want to hook up with the carriers. And that’s because NASA made a mistake: Inside the carriers, some capacitors were installed incorrectly. These capacitors, Tic-Tac-sized components that store electrical charge, need to have their positive ends in a specific spot and their negative ends in a different specific spot. And in the part of the carriers that powers payloads, engineers installed some capacitors backward. This is a no-no students learn in Electrical Engineering 101.

NASA is staffed by humans, and humans make mistakes sometimes. But the agency has a way of keeping track of those mistakes, in a system called Lessons Learned, so no one has to make the same slip-up twice. In the case of the reversed capacitors, though, “this error keeps reoccurring and is a ‘lesson not learned,’” according to a NASA report.

The Lesson Learned entry on capacitors came from way back in the year 2000, when Britney Spears released her second album, conveniently titled Oops…I Did It Again.

Preventable oopses like the reversing of capacitors waste time, energy, and taxpayer dollars. If the agency can keep a Mars rover rolling around the red planet for 12 years and counting, it can surely stick a few metal leads in the correct holes. Right?

In for a Shock

Engineers saw the first clues of the capacitor mistake in October 2012, when they were doing on-ground tests at NASA’s Kennedy Space Center. The spare carrier that lives on Earth started acting fishy, and power cut out intermittently. Investigators soon dug up the cause: A capacitor was leaking current, sending abnormal voltage out and upsetting the payload power supply, which then couldn’t energize an instrument. Two capacitors, it turns out, faced the wrong direction.

Uh oh, the scientists thought. Because they knew that spacefaring clones of this carrier were already on orbit. The same backward problem could be bothering them. That’s when Goddard Space Flight Center’s Electrical Engineering Division, which had designed and developed the equipment, called the NASA Engineering and Safety Center.

The safety officers soon found the root of the problem. And it had, in fact, branched into space. In designing the carrier, engineers had first planned to use capacitors that they could hook in any which way. But then they had changed the design, swapping in one-way capacitors. In between, no one had updated the blueprints. And so the circuit makers had made the circuits exactly as instructed, not paying attention to which way the capacitors faced. All four on-orbit carriers and the in-space spare turned out to have the same problem.

The backward capacitors, tests showed, fail fast when they consistently endure temperatures above 77 degrees Fahrenheit. That kind of heat is much more likely to happen in an on-ground test environment than in space. At lower space-y temperatures, the capacitors can live long and happy lives before they begin to leak current and kill power. So far, none of them have failed in space.

But NASA hopes to forestall future problems and prolong their lives. So to keep the experiments attached to the ISS from experiencing power outages, the agency has been monitoring temperatures and trying to make sure that none of the capacitors gets too hot.

One big source of heat is switching incoming power from 120 volts to 28 volts, which happens inside the carriers. So the agency has tried to limit the use of 28-volt power, hooking experiments into the higher-voltage source instead. But the problem here is that many payload parts were supposed to run on 28 volts. And that means some payload-makers have had to change their plans and add new equipment to their list of to-dos.

Houston, We Have a Power Problem

If you’ve ever traveled from one country to another, you know how your electric nose-hair clipper won’t work without an adapter. And that’s what the payloads now need. If teams had already started working on their experiments when NASA discovered its mistake, the agency gifted them converters. But for payloads not yet built, the cost came down on the experiment-makers themselves—other project teams in other wings of NASA—who have to amend their hardware designs to account for the problem.

That happened to the “Neutron-star Interior Composition Explorer/Station Explorer for X-ray Timing and Navigation Technology” team, whose instrument will launch in March 2017. In a NASA press release about the instrument last year, the agency mentions the Capacitor Issue without actually mentioning the Capacitor Issue, and then frames it as a space-age triumph of teamwork. “In just 11 months, the team developed a device that could convert the ISS-supplied 120 volts to 28 volts—in time to be included in the mission’s integration schedule,” it reads. “‘We’ve turned that into a success story,’ [principal investigator Keith] Gendreau said. ‘Again, it’s because we have a small, nimble team.’”

But downcoverting their power isn’t really their job, or at least not the job they signed up for, regardless of how nimble they are.

Also launching soon and accountable for others' mistakes are the Total and Spectral Solar Irradiance Sensor, which will help scientists understand how the sun’s radiation interacts with Earth; SAGE III, which measures aerosols and gases in the atmosphere; and CLARREO Pathfinder, which digs up the data necessary to test climate prediction models.

Capacity for Change

More fixes are in the works. In 2017, for instance, NASA will fly up a corrected unit and send a broken one back to the ground. There, they will fix it and make it available in case the capacitors do fail in space, although the experiments hooked into any failed unit would have to wait, possibly months, for their power-supply replacement.

The agency claims, basically, the whole thing is NBD, because they’ve adjusted, avoiding high temperatures and building in back-ups. “Exceedance of the temperature threshold on the other carriers for future payloads is not foreseen based on thermal predictions,” says NASA, practicing its passive voice.

When asked about extra costs associated with the mistake, NASA stated that they had already planned to build another spare and that “the ISS budget commonly takes into account repairs and refurbishments of system/facility hardware.”

Which is true and good. Things break! They need updates! But in this case, NASA just made lemons and then lemonade. Meanwhile, they could have used the money, time, and mental energy spent applying Band-Aids and back-up plans for new developments and unavoidable and unforeseeable problems, rather than the ones that a diagram double-check could have forestalled.