A few weeks after managers rejected a similar plan during the last shuttle flight, NASA officials hope extra lead time and better planning will permit a three-man Russian Soyuz capsule to undock from the space station and collect never-before-seen imagery of the shuttle Endeavour and orbiting lab linked together.

Animation of the space shuttle and space station docked together. Credit: NASA

Derek Hassmann, the lead International Space Station flight director for Endeavour's upcoming mission, told reporters Thursday NASA is again seeking Russian approval for the unique photo opportunity.

Nicknamed a "fly-about," the proposal was quashed during Discovery's mission earlier this month because the Soyuz that would be called upon for the maneuver was the first in a new series of capsules with upgraded digital electronics and navigation equipment.

Russian officials didn't want to alter their flight plan for the first-of-a-kind Soyuz vehicle. NASA and Russia also didn't start discussing the fly-about proposal until shortly before Discovery's launch in February.

Both Soyuz capsules expected to be at the space station during Endeavour's mission are among the last of the older version of the venerable craft. Hassman said the scenario now under consideration involves undocking the Soyuz TMA-21 spacecraft from the space station's Poisk docking module on the space-facing side of the lab's Russian segment.

"My hope is that we'll have a decision before the mission," Hassmann said. "If you look at the (STS-133) situation, they didn't start talking about it until about two weeks before launch. We have the benefit of the work they did."

If the unique flyaround is approved, the Soyuz TMA-21 spacecraft would undock from Poisk with NASA astronaut Ron Garan and Russian cosmonauts Alexander Samokutyaev and Andrey Borisenko inside. Armed with still photo and video cameras, the crew would back the Soyuz away from the outpost, do a partial flyaround of the complex and return to the space station less than an hour later.

"It's a significant operation that we need to look at closely to make sure we understand how to do it safely," Hassmann said. "There's nothing unsafe about the trajectory. the flyaround techniques are well understand the crew will be well-trained to go do it."

Photo of the shuttle Atlantis undocking from the Russian Mir space station in 1995. Credit: Roscosmos/NASA

Russia mounted a similar maneuver in 1995 when the shuttle Atlantis undocked from the Mir space station, snapping pictures of the spaceship and Mir separating in orbit.

Endeavour is scheduled to blast off April 19 with the $2 billion Alpha Magnetic Spectrometer international particle physics experiment and a platform of spare parts and science gear. The two-week mission would be extended a day to make time for the Soyuz fly-about, if approved.

Part of the motivation for the fly-about during Discovery's mission was the presence of all the space station's servicing vehicles at once, including the space shuttle, Europe's Automated Transfer Vehicle, Japan's H-2 Transfer Vehicle and Russian Soyuz and Progress craft.

The Japanese HTV is scheduled to depart the space station Monday, despite the earthquake and tsunami that rattled the country March 11. Although a family portrait of all the program's visiting spacecraft won't be possible during Endeavour's flight, officials say the photo opportunity is still appealing.

Engineers are also eager to get high-resolution video and imagery of the space station from fresh angles unseen during flyarounds by departing space shuttles, which stay along the outpost's velocity vector, or direction of travel, without providing any side views.