"UK schoolboy corrects Nasa data error" - what precisely was the "error"?

Question

From the BBC:

A British schoolboy has discovered that a piece of Nasa's top space research is flawed.

Miles Soloman, a student at Tapton School in Sheffield, was taking part in a project run by the Institute for Research in Schools. He told the World At One how he discovered that equipment used by the International Space Station was recording false data. (emphasis added)

A further BBC article and interview can be found here. From that article:

During UK astronaut Tim Peake's stay on the station, detectors began recording the radiation levels on the ISS.

"I went straight to the bottom of the list and I went for the lowest bits of energy there were," Miles explained. Miles's teacher and head of physics, James O'Neill, said: "We were all discussing the data but he just suddenly perked up in one of the sessions and went 'why does it say there's -1 energy here?'"

What Miles had noticed was that when nothing hit the detector, a negative reading was being recorded. But you cannot get negative energy. So Miles and Mr O'Neill contacted Nasa. "It's pretty cool", Miles said. "You can tell your friends, I just emailed Nasa and they're looking at the graphs that I've made."

It turned out that Miles had noticed something no-one else had - including the Nasa experts. Nasa said it was aware of the error, but believed it was only happening once or twice a year. Miles had found it was actually happening multiple times a day.

Prof Larry Pinksy, from the University of Houston, told Radio 4: "My colleagues at Nasa thought they had cleaned that up.

Precisely what NASA top space research "is flawed" because it is recording "false data"? What data stream are we talking about, and is the problem catastrophic, or just LSB noise (least significant bit).

Answer 1

The source of the data is the Radiation Environment Monitor. Lawrence S. Pinsky is listed as co-investigator.

This Radiation Environment Monitor demonstration will provide information that is required to enable the design of an operational active personal space radiation dosimeter.

The objectives of the experiment are to demonstrate the viability of this technology in the space radiation environment and the ability to assess crew exposure in near real time (via ground software).

In order to effectively manage radiation risks to crewmembers during long-duration space exploration beyond low Earth orbit, there is a strong need to monitor personal radiation exposure in near real time. The current technology uses passive dosimetry techniques and associated logistics that require down-mass and ground analysis which provides radiation dose information several months after return. The REM is a low mass, low volume and low power dosimeter that may meet the near real time exposure monitoring of crew members.

The REM devices are USB sticks.

The error was a misunderstanding of the root cause of the negative values:

NASA had apparently already known about this issue, but they thought it was only occurring once or twice a year due to a problem with an algorithm. But Soloman found it was occurring multiple times a day.

Why the REM records negative values remains to be seen.
But it is not unusual to use 'impossible values' to convey information, where -1 could mean 'measurement out of range'. There's a name for this phenomenon, but that escapes me at the moment.

If you misread the -1 as a literal value, its impact depends on the rest of the data. If the data has a range of 0-10000, the impact of having a few instances of -1 that should be 0 is small. If the values are in the range of 0-10, its impact is much larger.