(CNN) -
SpaceX Chief Executive Elon Musk said on social media last night that he conducted four covid-19 tests in one day, two of which were positive and two negative.
It's not yet clear whether Musk has the virus, but the news immediately raised concerns about whether a diagnosis will affect SpaceX's plans to send astronauts on a mission to the International Space Station this weekend.
Musk issued a short series of tweets during the night, stating that he had "mild colds," "cough," and "mild fever" for the past few days.
He added that he hopes to get the results of a PCR test, which is known to be more accurate than the type of rapid test Musk said he took, within 24 hours.
Meanwhile, Musk's tweets echoed across the country to the Kennedy Space Center in Florida, where four astronauts prepare to travel into space aboard a SpaceX Crew Dragon capsule on Sunday.
LOOK: What you need to know about Crew-1 the first mission of SpaceX and NASA
NASA chief Jim Bridenstine, who was scheduled to hold a routine press conference Friday morning, told reporters who inquired about Musk's tweets that under NASA policy, Musk should be in quarantine and SpaceX would try to determine who might have been in contact with Musk.
On Friday night, during another routine press conference, NASA and SpaceX officials at the Kennedy Space Center said contact tracing was largely complete and determined that no one is essential to the mission to this end. week was at risk of exposure to covid-19.
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Astronauts are almost certainly not at risk, according to NASA's deputy director of flight operations Norm Knight.
The space agency has regularly tested anyone who has been close to the crew.
Even before the pandemic, NASA astronauts have adhered to pre-flight quarantine rules to ensure they don't carry a disease into space, where viruses and bacteria could spread rapidly between crew members in a space. spaceship.
NASA also implemented stricter measures in response to COVID-19.
For two weeks prior to launch, the astronauts have been in "hard quarantine," meaning they are "totally isolated" and cannot be near anyone outside the launch team, not even their families, Knight said.
MORE: Step by step: this will be the launch and docking of Crew-1
And Musk, he added, will not be able to enter the NASA facility on launch day.
"It is restricted access," he said.
“It doesn't matter if you are Elon Musk or Jim Bridenstine… if any [of NASA's covid-19 protocols] have been compromised, then we won't let you get anywhere near the crew.
And again, it is to protect the mission in general.
It is unclear whether Musk had planned to attend the Florida launch, although he is frequently seen at SpaceX launch control at the Kennedy Space Center during major SpaceX missions.
SpaceX's manned spaceflight program chief Benji Reed said SpaceX's mission control center in Hawthorne, California, meets strict health and safety regulations.
Employees playing critical roles in the launch process have been tested, temperature controlled and quarantined to ensure their health ahead of this weekend's mission.
Reed also urged members of the public not to ignore Covid-19 if they choose to watch the launch from the ground in Florida this weekend.
"We know that everyone is very excited about the launch and very excited about recovery and manned space flight in general," said Reed.
“We certainly ask everyone involved, if you come to see the launch… please wear your masks and follow the social distancing guidelines.
Do the right thing there to keep everyone safe.
The mission is scheduled to take off on Sunday at 7:27 pm Miami time.
The original launch date was Saturday night, but officials delayed it due to unfavorable weather conditions, NASA and SpaceX officials said.
Why Musk's Tests May Have Been Incorrect
Musk said on Twitter that the four tests he performed Thursday were rapid tests, or "antigen tests," performed by the same nurse at the same facility.
He alleged in his late-night tweets that something "extremely false" was happening, echoing months of previous tweets in which Musk has expressed doubts about the COVID-19 threat.
He also previously shared a YouTube video that was later removed for containing misinformation about the virus.
In a recent interview with journalist Kara Swisher, Musk doubled down on his skepticism, said he would not take a COVID-19 vaccine when it becomes available, and insisted that confinement orders designed to reduce the spread of the virus did more harm than good.
Elon Musk says he will not be vaccinated against covid-19 1:16
In fact, medical professionals are well aware that rapid antigen tests can be inaccurate and lead to false negatives or, more bizarrely, false positives.
PCR tests, on the other hand, can take a day or more to return results, but they are much more accurate.
This is because PCR tests look for signs of the genetic material of the covid-19 virus, while antigen tests look for one of the viral proteins or a small trace of the presence of the virus.
And although both types of tests are based on a nasal swab, PCR tests require complicated specialized laboratories and trained technicians to perform.
That's why in the early days of the pandemic, PCR tests were long overdue, sometimes taking more than a week to return results.
Antigen tests were expected to provide a faster, if less accurate, picture of how the new coronavirus was spreading across the United States.
Musk also called the company that made the antigen tests he conducted Thursday, New Jersey-based medical technology company BD.
MORE: SpaceX rockets are designed to be reusable.
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Jessica Offerjost, BD's communications manager, responded in an emailed statement to CNN Business, saying the company "is aware of the tweet and is trying to get information more consistent with our quality management process."
"While the scientific community agrees that no diagnostic test is perfect, we stand behind the quality, utility and science of our system," the statement read.
“There are many factors that could lead to a discordant result… As we clearly state in our instructions for use, negative results should be considered in the context of a specific patient situation and confirmed with a molecular PCR assay if necessary for management of the patient '.
According to Musk's tweets, he expects to receive the results of his PCR test on Friday night.
She also noted that she was currently experiencing no symptoms, although she "took NyQuil."
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