US astronaut, Christina Koch breaks record for longest spaceflight by a woman

SAN FRANCISCO -- A U.S. astronaut has set a record for the longest single spaceflight by a woman.

NASA officials say Christina Koch on Saturday broke the 288-day record set by former space station commander Peggy Whitson.

The 40-year-old electrical engineer from Montana has been in space since March 15.

She is expected to spend about 11 months on board the International Space Station, falling short of astronaut Scott Kelly's 340-day U.S. record.

A Russian cosmonaut holds the world record at 15 months on a single mission aboard the former Mir space station in the mid-1990s.

NASA tweeted "It's a new day. It's a new dawn," and shared space photos on twitter.

The International Space Station wished Koch congratulations on the new record in this tweet:

ABC7 News contributed to this report.