WASHINGTON — The $400 million for NASA exploration efforts contained in the $787 billion economic stimulus package could pay for an additional test flight of the space shuttle’s planned successor or hasten other work on the system that had been delayed by budget constraints, a NASA official said here Feb. 25.

The exploration money is part of a $1 billion windfall for NASA in the stimulus bill, which was signed into law Feb. 17 by U.S. President BarackObama. Also included is $400 million for Earth science and climate monitoring activities; $150 million for aeronautics; and $50 million to repair NASA facilities damaged by Hurricane Ike and Hurricane Gustav last summer.

In approving the bill, Congress gave no direction to NASA on how to spend the exploration money. NASA, which still does not have an administrator, has until mid-April to come up with a detailed plan.

Doug Cooke, associate administrator of NASA’s Exploration Systems Mission Directorate, said the agency is looking at how to best put the money toward the space shuttle’s successor — a crew-carrying capsule dubbed Orion that would launch on a shuttle-derived rocket called Ares 1. The system is slated to debut in 2015, or five years after the space shuttle’s planned retirement. During the interim, NASA plans to rely on Russian Soyuz vehicles to transport astronauts to and from the international space station.

An additional test flight of an Ares 1 prototype “is certainly within the realm of possibilities,” Cooke said. NASA is planning to launch the Ares 1-X prototype in July and a second prototype called Ares 1-Y in 2013. Inserting a test flight between the two has been discussed previously but there has not been enough money to pay for it.

Cooke said the stimulus money also could go toward Ares and Orion work in 2009 and 2010 that had been delayed by budget constraints.

“We’re putting together plans right now on how to best take advantage of that in terms of reducing risks in our program,” Cooke said Feb. 25 at a Lunar Surface Systems Concepts workshop here. “This actually helps bring some work back in that will help us develop in a more serial fashion than we’ve been able to do.”

Scott Horowitz, former associate administrator of NASA’s Exploration Systems Mission Directorate, estimates that each additional $100 million spent on Ares and Orion could accelerate those vehicles by about one month.

Horowitz, one of the key architects of NASA’s space shuttle replacement plan, said the stimulus money could buy hardware to speed up production of the Ares 1’s J2-X upper-stage engine, or be put toward accelerating or adding tests of Orion and its launch abort system. NASA also could pour more resources into launch pad and other infrastructure modifications at NASA’s Cape Canaveral, , to keep workers there employed as the shuttle program winds down, he said.

“Any work on the production line on Orion and on infrastructure is helpful in damping the transition pain down at the,” Horowitz said.

Meanwhile, Space Exploration Technologies (SpaceX), one of two companies developing space station logistics services under NASA’s Commercial Orbital Transportation Services (COTS) program, has a different idea for how the stimulus money should be spent — one that the company says would substantially reduce the looming gap in U.S. human spaceflight capabilities.

Gwynne Shotwell, president of Hawthorne, Calif.-based SpaceX, said for $300 million the company could develop within two years a crew-carrying version of its planned Dragon logistics capsule.Shotwell said SpaceX would charge between $10 million and $15 million per crew member for flights to the space station aboard the vehicle.

NASA announced in December that it would pay $141 million to launch three crew members to the space station in fall 2011. The fixed-price contract calls for dividing the three crew members between two Soyuz flights.

“If you look at the grand scheme of things, $300 million is not a lot of money to develop this kind of capability,” Shotwell said. “And then you have it domestically rather than having to send astronauts up on Russian capability.”

Shotwell said the Dragon capsule was designed from the start to be upgraded to carry astronaut crews.

“We’ve designed the structure to accommodate a concept for a launch escape system – we just need to design, build and qualify it,” she said.

Horowitz is skeptical.

“You can’t do anything in aerospace in less than three and a half years,” said Horowitz. “I think we should support [SpaceX], I think we should give them some money, but to say they can do that in 24 months is ludicrous.”

Because the broad intent of the economic stimulus package is to stem rising unemployment through programs that can quickly create and retain jobs, Congress likely will let NASA’s leadership decide how to spend the money without much debate, said Paul Carliner, a former senior staffer on the Senate Appropriations subcommittee that oversees NASA’s budget.

“You want to avoid a fight over something like this because it is a stimulus, and you want to get it out quickly,” Carliner said. “No one wants to be seen as holding up a stimulus bill; that doesn’t help anybody.”

Congress anticipates Obama will appoint a new NASA administrator soon enough to direct the agency’s spending of the stimulus money, Carliner said.

The change in administrations has rekindled debate over the space shuttle’s retirement schedule, NASA’s choice of replacement vehicles and options for mitigating the human spaceflight gap. Congress likely will be asking about these issues during the confirmation of the president’s nominee for NASA administrator and during debate over the agency’s 2010 budget request, Carliner said.