Cape Canaveral, Fla. ? The stars may have finally aligned for the world’s only space sibling team.

Astronaut Scott Kelly is circling the planet, fresh into a 5 1/2-month space station mission. His identical twin, Mark, will join him next year, if NASA’s shuttle schedule holds up.

Together, they will become the first blood relatives to meet up in space.

“It’s something we hoped would happen,” Mark said. “It wasn’t done by design. But we’re fortunate. I think it will be fun for us.”

Scott is the International Space Station’s next commander. He took off aboard a Russian Soyuz rocket early Friday — texting and joking with his brother right until launch — and arrived at the orbiting complex Saturday night.

Mark is space shuttle Endeavour’s next commander. He’s due to take off at the end of February and knock on the space station door March 1. It’s currently slated to be NASA’s last shuttle flight.

Mark couldn’t resist a little twin humor in a congratulatory call to his brother at the space station.

“Hey Mark, this is Scott,” Mark radioed from Mission Control outside Moscow. “You know, six months is a long time in space. So thanks for switching spots with me. Just hope I can remember how to fly that space shuttle.”

Don’t expect any handshakes when the Kellys unite more than 200 miles up. The 46-year-old brothers — Navy captains and former fighter pilots — have never shaken each other’s hands and don’t plan to start just because the space station cameras are rolling.

Rather, count on embraces and even arm-wrestling when the hatches pop open between the space station and Endeavour, and the world does a double take.

For now, anyway, there’s a little difference — Scott is clean-shaven and Mark has a mustache.

The Kellys promise no gags or matching outfits in space. They insist they’ve never done any of that.

So how will they mark the historic occasion?

The Associated Press posed the question in a recent interview.

“We’re going to arm-wrestle,” replied Mark.

“I was going to say the same exact thing,” said Scott.