NASA paid $5 million for a probe into drug use at SpaceX after Elon Musk was filmed smoking weed. It still won't say what it found.

• Elon Musk appeared to smoke pot while taping an episode of Joe Rogan's podcast in 2018.
• One week later, NASA launched a probe into drug use at SpaceX.

The National Aeronautics and Space Administration probably knows quite a bit about Elon Musk's drug use, but it won't say what.

The agency spent three months reviewing SpaceX's commitment to a drug-free workplace, among other safety measures, after Musk was filmed smoking a spliff in 2018. Business Insider obtained the results of that investigation under the Freedom of Information Act, but NASA redacted the document so heavily it's impossible to determine what the agency found.

BI went looking for the results of NASA's drug use probe, which it calls an "organizational safety assessment," after the Wall Street Journal reported this summer that Musk "microdoses ketamine," spurring new questions about the drug use of the world's richest person.

The space agency initially responded to BI's request by claiming it didn't have any records of the assessment's results. Public records request logs, and emails provided by NASA, show that the agency told a Wall Street Journal reporter the same thing in 2022.

But after Business Insider reminded the agency that it had paid SpaceX $5 million in taxpayer dollars to conduct the investigation, NASA coughed up the letter initiating the probe, a scope of work, and the final report.

The documents show that NASA told SpaceX that it would be investigating the company's corporate culture less than a week after Musk was filmed putting a giant spliff to his lips on Joe Rogan's podcast on September 6, 2018. (Musk later said he never actually smoked, adding that he has "no idea" how to do so.)

NASA's Associate Administrator William Gerstenmaier wrote to SpaceX president and COO Gwynne Shotwell expressing "NASA's concerns regarding SpaceX's safety and health practices" on September 12, 2018, and asked the company to "participate in an organizational safety assessment."

"It is essential for the integrity of the United States space program to ensure that the development and production of the space systems that will transport astronauts is conducted in a manner that prioritizes safety," Gerstenmaier wrote. "The Safety and Health provision in the contract requires SpaceX to comply with standard industry practices, applicable laws, and other relevant provisions of the contract, such as the requirement to maintain a drug-free workplace."

SpaceX did not respond to a request for comment.

The probe spanned SpaceX facilities in California, Texas and Florida, the records show. Investigators interviewed 296 SpaceX employees "at all levels of personnel," half of whom worked on the commercial crew program that shuttles astronauts to the International Space Station.

Despite the assessment's hefty price tag and NASA's insistence that it was "essential to the United States space program," the agency covered the results of the probe in black ink, citing a public records exemption that allows it to withhold documents if they "could harm the competitive posture or business interests of a company."

A NASA spokesperson said that the "results of the assessment are company proprietary, and NASA does not intend to release the results publicly."

Gerstenmaier, the NASA administrator who requested the review, left the agency several months after the conclusion of the probe. Less than a year later, he got a job at SpaceX, where he's now the vice president of build and flight reliability.

Do you know anything about NASA's safety assessment at SpaceX? Contact reporter Katherine Long on the encrypted messaging app Signal at +1-206-375-9280. Use a non-work device.