The two new programs provided in the budget request include space platforms as the first elements of the Mission to Planet Earth, an ambitious plan to study Earth and its threatened environment from orbit, and the "human exploration initiative."

Administration officials said Mr. Bush would again propose an increase in NASA's budget for 2006 to support the exploration initiative.

I recently celebrated my 27th year with NASA, having worked throughout my career on some of the nation's most important and exciting science and exploration initiatives.

Under the Bush plan, money for the exploration initiative would come from ending space shuttle operations by 2010 and ending use of the International Space Station in 2016.

In the past, it has cooperated with the British Geological Survey on geological mapping and geochemical exploration initiatives, but due to economic issues and a loss of funding, it has been unable to continue mapping.

The people who constructed the drone call themselves the Dokaalan, and the device itself was not launched from their homeworld as part of an exploration initiative.

Mr. O'Keefe helped in formulating a new space policy, which President Bush announced last January as a pay-as-you-go exploration initiative to send humans to the Moon and, later, to Mars.

The exploration initiative is seen as a pay-as-you-go program, he said, because it stays within current budgets and calls for finishing one step, like building a new human spacecraft, before going on to another.

"We're also looking at how you manage an effort as large and long as the human exploration initiative," said James C. Harrington, chairman of the panel.

"NASA should not step away from this pre-eminence in science through an overly narrow interpretation of the exploration initiative," the astronomers wrote.