What is the next best thing to going into space? Being next in line for a trip.

Esther Dyson, philanthropist, investor in aerospace, information technology, and one successful start-up venture after another, has signed up with Space Adventures to start training for a flight to the International Space Station.

Space Adventures president and CEO Eric Anderson said that “as many of our investors are also space enthusiasts, we are delighted that as a back-up crew member, Esther will experience first-hand how our clients train for spaceflight.”

After successful completion of the training program, Dyson will be certified as a fully trained cosmonaut and will be named to an official space mission crew. She will be training with the next Space Adventures client to make the journey, Dr. Charles Simonyi.

Dyson said, “I am thrilled to be training as a cosmonaut and learning about space travel firsthand—especially with Charles, whom I have know since the ‘80s when he was writing software for Microsoft. I fully expect to follow him all the way up to space sometime in the future. My father helped design a rocket ship when I was a kid, and I have always assumed I will go into space myself.”

One special note: unless another woman beats her to it, Ms. Dyson will be the second female Space Adventures client after Anousheh Ansari, entrepreneur and financier of the Ansari X-Prize, captured in 2004 by Burt Rutan’s SpaceShipOne.

Being second may not be the same as being first, but as Anderson said, “This is a distinction that less than 1,000 people have ever had. We look forward to the day when she launches into space herself.”

She will blog about her training on her web site.