Two Saudi astronauts have entered mandatory quarantine in Florida before they head into space this month.
Rayyanah Barnawi, set to become the first Saudi woman to go to space, and Ali Al Qarni will blast off on a 10-day trip to the International Space Station (ISS) as part of a private mission by Axiom Space.
A SpaceX Falcon 9 rocket is scheduled for lift-off at 1.37am GST (May 21, 5.37pm ET) from the Kennedy Space Centre in Cape Canaveral.
"In preparation for launching to the International Space Station this May, astronauts Rayyanah and Ali have arrived in Florida for their quarantine period before they launch on their scientific mission," the Saudi Space Commission tweeted on Tuesday.
"We wish success to our heroic pioneers on this historic journey."
Astronauts are required to quarantine at least two weeks before a spaceflight to avoid exposing their spacecraft and other crew members on the ISS to germs.
Two Americans will join the Saudis on their trip — former Nasa astronaut Peggy Whitson and pilot John Shoffner.
"After a long journey in which our training continued in preparation for launching into the mission, your support motivated us during that period," Mr Al Qarni tweeted.
"Today, we have successfully completed our training for the mission, and we start the quarantine period before launching into space, to ensure our health and the launch of the mission on time soon, God willing.
"We are ready to embark on our mission and put a new footprint for the Kingdom in the promising space sector."
Once their Dragon spacecraft docks at the ISS on May 23, they will join UAE astronaut Sultan Al Neyadi, who is there on a six-month mission.
The trip comes nearly 40 years after Saudi Arabia sent its first citizen, Prince Sultan bin Salman, into orbit on Nasa's Space Shuttle for a week-long stay.
Ms Barnawi will become the first Arab woman on the ISS. Egyptian engineer Sara Sabry became the first Arab woman in space when she travelled on a Blue Origin tourism flight in August.
The two Saudi astronauts will be carrying out several scientific experiments on this month's trip, assigned to them by Saudi universities.
One of the experiments involves testing cloud-seeding techniques in a reaction chamber.
Another entails studying the inflammatory response of human immune cells in microgravity.
They will investigate changes in the mRNA — a genetic material that tells the body how to make proteins.
