Two crucial tools for a successful Mars landing -- the spacecraft's radar and UHF radio -- were briefly powered up and operated according to specifications, NASA said.

The ultra-high-frequency radio won't be turned on again until landing day, May 25, when it will relay communications from Phoenix to orbiters already in service around Mars.

Since its Aug. 4 launch, and until it reaches Mars, Phoenix is communicating with NASA's Jet Propulsion Laboratory in Pasadena, Calif., via even higher frequency X-band radio using a transmitter that will be jettisoned shortly before Phoenix enters the Martian atmosphere.

The radar will monitor the final three minutes of the spacecraft's descent to the surface of Mars, triggering necessary events during the most challenging moments of the mission, NASA said.

Four additional science instruments are scheduled for checkouts before the spacecraft's next trajectory correction maneuver, planned for Oct. 16.

As of Sept. 1, Phoenix had covered 50 million miles of its 422-million-mile flight to Mars, traveling at 76,000 mph.