LOS ANGELES, California - Leaders of two private space ventures that suffered failures vowed today to try, try again.

Louis Friedman, Executive Director of The Planetary Society based in Pasadena, California, said that they are proceeding with a privately-backed Cosmos 2 solar sail effort.

The earlier Cosmos 1 sail was launched skyward on June 21 of last year atop a Russian sub-launched Volna rocket. But the submarine-launched booster's first stage shut off, with the mission failing some 83 seconds into flight, Friedman told attendees of the International Space Development Conference (ISDC) that began today.

"It never made it to orbit," Friedman explained, noting that the Volna rocket suffered a first stage turbopump failure. "We'll try it again," he said.

Friedman said that some money has been raised for the Cosmos 2 sail project, but they are looking for a new sponsor for the mission.

While calling use of the Volna rocket "a worthy attempt," Friedman said the next solar sail would ride upon a Soyuz-Fregat or Cosmos 3M launcher as a piggyback payload.

Falcon re-flight

Also addressing the opening day of the ISDC meeting at a "Space Venturing Forum" was private rocketeer, Elon Musk, chairman and chief executive officer of El Segundo, California-based Space Exploration Technologies (SpaceX).

The SpaceX Falcon 1 rocket failed March 24 of this year, shortly after liftoff from a launch pad on Omelek Island. The private rocket's maiden flight suffered a fuel leak, leading to a main engine shutoff, Musk recounted.

"The rocket business is a tough business," Musk said.

Musk said that an on-the-pad processing error by a couple of technicians the day before launch doomed the vehicle. SpaceX engineers are now putting in place improvements in several areas, particularly in processing the rocket booster for launch--incorporating "fool proof" design changes, as well as improving a health-monitoring software check system used on the rocket, he added.

"We've had hundreds of engine tests ... and not once did the problem that occurred on launch day show up," Musk stated. "When we make it ... it sure won't be luck."

The problem cropped up, ironically, in the part of the booster that ground personnel check for leaks in the engine, Musk explained.

Next flight of the Falcon--a demonstration flight--is slated for September, Musk advised.

Musk said that SpaceX has some 11 launches that have now been sold.

Asked about his company's interest in building a crew capsule, Musk said that if SpaceX wins soon-to-be-announced NASA crew and cargo transport work, the entrepreneurial firm will accelerate building of the hardware.

Given the NASA win, the crew capsule would be available roughly three years from now, Musk said. Without the contract work, a scaled-down version would be available in 2011, he said.