WASHINGTON — Singer Sarah Brightman abruptly canceled her plans May 13 to travel to the International Space Station later this year as a space tourist on a Soyuz flight.

Brightman, who had been training for several months at Russia’s Gagarin Cosmonaut Training Center outside Moscow, said in a statement that “personal family reasons” led her to postpone her flight to the ISS, but did not elaborate.

“We’ve seen firsthand her dedication to every aspect of her spaceflight training and, to date, has passed all of her training and medical tests,” Eric Anderson, chairman of Space Adventures, the company that arranged her flight, said in a statement. “We applaud her determination and we’ll continue to support her as she pursues a future spaceflight opportunity.”

When Brightman might have a future opportunity isn’t clear. Brightman took advantage of rare open seats on a Soyuz created by the “one-year” mission on the ISS by NASA astronaut Scott Kelly and Roscosmos cosmonaut Mikhail Kornienko. Because Soyuz spacecraft are rated to spend only about six months in space, a new Soyuz is flying in September to replace the one that launched Kelly and Kornienko in March.

NASA officials have discussed performing additional one-year missions, but the agency has yet to schedule any with the other ISS partners. The introduction of commercial crew vehicles under development by Boeing and SpaceX, each able to carry up to seven people, could also provide opportunities for space tourists, but those vehicles will not be available until 2017 at the earliest.

Also uncertain is what will happen to the seat on the Soyuz TMA-18M flight that Brightman has given up. In January, Space Adventures announced that Japanese advertising executive Satoshi Takamatsu would train as Brightman’s backup. However, the Space Adventures announcement of Brightman’s plans made no mention of Takamatsu, and the company did not respond to an inquiry about its plans.

Brightman’s flight to the ISS was scheduled to launch Sept. 1. On May 12, though, NASA announced the date of the mission before it, TMA-17M, had been rescheduled from May 29 to late July because of the ongoing investigation into the Progress failure. Dates of future missions, including TMA-18M, were “under review” as a result of that delay.

Prior to the May 13 announcement, there had been rumors in the Russian media that Takamatsu might replace Brightman because he was deemed to be better trained for the mission. Russian officials, though, denied those reports.

“Everything is all right and goes according to the schedule,” Yury Lonchakov, head of Russia’s mission control center, told the Russian news service TASS April 28 when asked about those reports.