Using this concept, some aerospace analysts believe the way to lower launch costs is the exact opposite of SSTO.

Dr Jeff Foust is an aerospace analyst, journalist and publisher.

"Yes, external factors have played a role," said Byron Callan, an aerospace analyst at Merrill Lynch.

"It's a move of big strategic significance," said George Shapiro, the aerospace analyst for Solomon Brothers.

An aerospace analyst, Fujio Nakano, said the decision to shift focus to the H-2A was a good idea.

But some aerospace analysts said the move to team up suggests that the plane is not a realistic business project.

"Everyone sees the numbers, but they're not quite sure where it's going to go," said Byron Callan, an aerospace analyst for Merrill Lynch.

"They took all the risk," said Christopher Demisch, an aerospace analyst at the First Boston Corporation.

"This is a watershed event," said Howard Rubel, an aerospace analyst with Jeffries & Company.

Andrew Brookes is an English aerospace analyst, author of aviation books and aviation journalist.