Washington ? NASA is allowing a highly successful satellite to fall out of Earth’s orbit by refusing to fund it for as little as $28 million, dismaying the scientists and forecasters who use its unique abilities to study climate change and track hurricanes.

NASA officials said engineers did not order a planned firing of its rockets in early July to hold the Tropical Rainfall Measuring Mission satellite in orbit 241 miles above Earth. Without assists from its thrusters, atmospheric drag will send the satellite’s remains to a watery grave in six to nine months.

Engineers said the satellite, a joint venture with the Japanese Aerospace Exploration Agency, was working perfectly and could still be saved, but NASA officials said neither the Japanese nor other U.S. agencies were willing to contribute to the estimated $28 million to $36 million needed to keep the mission operating for as long as two more years.

The satellite is a unique space platform whose instruments have proved invaluable not only to researchers studying global change, but also to meteorologists who use its one-of-a-kind “rain radar” to probe deep into cloud cover to determine whether the makings of a cyclone lurk there.

In 2002 a NASA study determined the potential lifesaving value of the satellite was great enough to justify keeping it aloft until it ran out of fuel and tumbled unguided back to Earth, possibly killing or injuring someone.

The decision instead to use a “controlled deorbit” for the satellite, known by its initials TRMM, was announced quietly July 13 in an internal NASA memo, and came at a time when NASA’s Earth observation budget is shrinking as the agency begins to focus on President Bush’s plan for human exploration of the moon and Mars.

NASA officials said the agency decided to deorbit TRMM because the money saved could be put to better use on a next-generation satellite scheduled for launch in 2011.