NASA's Mars Reconnaissance Orbiter successfully received information from the Phoenix Mars Lander Tuesday evening and relayed the information to Earth. The relayed transmission included images and other data collected by Phoenix during the mission's second day after landing on Mars.

The UHF radio system used by the orbiter to communicate with the lander had gone into a standby mode earlier Tuesday for a still undetermined cause. This prevented sending Phoenix any new commands from Earth on Tuesday. Instead, the lander carried out a backup set of activity commands that had been sent Monday.

A helical UHF antenna mounted on the lander deck sends and receives all communications. The helical antenna and a monopole UHF antenna, also mounted on the deck, will be used for relay telecommunications during the months of operation after landing. The lander can send data at rates of 8,000 bits per second, 32,000 bits per second or 128,000 bits per second. The lower two speeds are the choices for receiving commands relayed to Phoenix from an orbiter.

Mission scientists are eager to move Phoenix's robotic arm, for that arm will deliver samples of icy terrain to their instruments made to study this unexplored Martian environment.

The first samples fed into the lander’s analyzers will come from the surface. Decisions about how much deeper to go before analyzing another sample will depend on results from the surface material and on what the robotic arm camera and stereo imager see in the soil. The Thermal and Evolved-Gas Analyzer can check for organics and other volatiles in up to eight samples. Researchers must be choosier with samples for the wet chemistry laboratory of the Microscopy, Electrochemistry and Conductivity Analyzer, which can examine four different samples.

The Phoenix weather station, provided by the Canadian Space Agency, was activated within the first hour after landing on Mars, and measurements are now being recorded continuously.

The Meteorological Station will track daily weather and seasonal changes using temperature and pressure sensors plus a laser-reflection instrument. The information collected by this first high-latitude weather station on Mars will aid understanding of how water is cycled seasonally between ice on the ground and vapor in the atmosphere.

The laser tool, called a lidar for “light detection and ranging,” uses powerful laser pulses in a way comparable to radio pulses emitted by a radar instrument. The laser beam is emitted vertically into the atmosphere. Atmospheric dust and ice particles in the beam’s path reflect the light, sending it in all directions, including straight downward. A telescope integrated into the instrument detects the downward-reflected light. Analysis of the strength and time-delay of the reflections reveals information about the sizes and altitudes of the particles. Tracking changes in these atmospheric particles’ abundances and locations over time will help researchers study how clouds and dust plumes form and move.

The weather station includes a 1.2-meter (4-foot) mast bearing sensors at three heights to monitor how temperature varies with height near the surface. The temperature sensors are thin-wire thermocouples; they measure temperature by its effect on the flow of an electrical current through a closed circuit of two metals with different thermal properties. The thermocouples use the metals chromel (a nickel and chromium alloy) and constantan (a copper and nickel alloy).

Also, hanging from the top of the mast is a wind telltale. This is a small tube that will be deflected by the wind. The science payload’s stereo camera will record images of the telltale that will be used to determine wind direction and speed. The top of the meteorology mast, at 1.14 meters (3.75 feet) above the deck, is the highest point on the lander.

NASA's Mars Odyssey orbiter is scheduled for relaying commands to the lander on Wednesday morning.