January 25 

25 January 1994

Clementine spacecraft undergoes final checks. Credit: U.S. Naval Research Laboratory

Clementine spacecraft, a lunar orbiter and planned asteroid probe, was launched on January 25, 1994, at 16:34:00 UTC from Space Launch Complex 4 West at Vandenberg Air Force Base, California, using a Titan II launch vehicle. Clementine was the first U.S. lunar spacecraft since 1973.  

   The mission was designed to test sensors and spacecraft components during extended exposure to space for the DOD’s Brilliant Pebbles program for the Strategic Defense Initiative, and to study the Moon and the near-Earth asteroid (1620) Geographos. Clementine entered lunar orbit on February 19, 1994 and remained there until May 4, 1994. The spacecraft created the first global topographic map of the Moon and found evidence of ice in the bottom of a permanently shadowed crater at the Moon's south pole. The mission succeeded in its lunar objectives, but a malfunction on May 7, 1994, forced the planned asteroid flyby to be cancelled. The mission ended in June 1994.

Lift-off of a Titan II 23G launch vehicle with Clementine. Credit: U.S. Department of Defense

Full Description from NASA Space Science Data Coordinated Archive:

Clementine was a joint project between the Ballistic Missile Defense Organization (BMDO, nee the Strategic Defense Initiative Organization, or SDIO) and NASA. The objective of the mission was to test sensors and spacecraft components under extended exposure to the space environment and to make scientific observations of the Moon and the near-Earth asteroid 1620 Geographos. The Geographos observations were not made due to a malfunction in the spacecraft. The lunar observations made included imaging at various wavelengths in the visible as well as in ultraviolet and infrared, laser ranging altimetry, gravimetry, and charged particle measurements. These observations were for the purposes of obtaining multi-spectral imaging the entire lunar surface, assessing the surface mineralogy of the Moon and obtaining altimetry from 60N to 60S latitude and gravity data for the near side. There were also plans to image and determine the size, shape, rotational characteristics, surface properties, and cratering statistics of Geographos. Clementine carried seven distinct experiments on-board: a UV/Visible Camera, a Near Infrared Camera, a Long Wavelength Infrared Camera, a High Resolution Camera, two Star Tracker Cameras, a Laser Altimeter, and a Charged Particle Telescope. The S-band transmitter was used for communications, tracking, and the gravimetry experiment.

Clementine topographic map of the Moon. Credit: Lunar and Planetary Institute

Spacecraft and Subsystems

   The spacecraft was an octagonal prism 1.88 m high and 1.14 m across with two solar panels protruding on opposite sides parallel to the axis of the prism. A high-gain fixed dish antenna was at one end of the prism, and the 489 N thruster at the other end. The sensor openings were all located together on one of the eight panels, 90 degrees from the solar panels, and protected in flight by a single sensor cover. The spacecraft propulsion system consisted of a nonpropellant hydrazine system for attitude control and a bipropellant nitrogen tetraoxide and monomethyl hydrazine system for the maneuvers in space. The bipropellant system had a total capability of about 1900 m/s with about 550 m/s required for lunar insertion and 540 m/s for lunar departure. Attitude control was achieved with 12 small attitude control jets, two star tracker cameras, and two inertial measurement units. The spacecraft was three-axis stabilized in lunar orbit via reaction wheels with a precision of 0.05 Deg. in control and 0.03 Deg. in knowledge. Power was provided by gimbaled, single axis, GaAs/Ge solar panels which charged a 15 amp-hour, 47 W-hr/kg Nihau (Ni-H) common pressure vessel battery. Spacecraft data processing was performed using a MIL-STD-1750A computer (1.7 million instructions per second) for savemode, attitude control, and housekeeping operations, a RISC 32-bit processor (18 million ips) for image processing and autonomous operations, and an image compression system provided by the French Space Agency CNES. A data handling unit sequenced the cameras, operated the image compression system, and directed the data flow. Data was stored in a 2 Gbit dynamic solid state data recorder.

Mission Profile

   The mission had two phases. After two Earth flybys, lunar insertion was achieved approximately one month after launch. Lunar mapping took place over approximately two months, in two parts. The first part consisted of a five hour elliptical polar orbit with a periapsis of about 400 km at 30 degrees south latitude and an apoapsis of 8300 km. Each orbit consisted of an 80 minute lunar mapping phase near periapsis and 139 minutes of downlink at apoapsis. After one month of mapping the orbit was rotated to a periapsis at 30 degrees north latitude, where it remained for one more month. This allowed global imaging and altimetry coverage from 60 degrees south to 60 degrees north, over a total of 300 orbits. After a lunar/Earth transfer and two more Earth flybys, the spacecraft was to head for Geographos, arriving three months later for a flyby, with a nominal approach closer than 100 km. Unfortunately, on 07 May 1994, after the first Earth transfer orbit, a malfunction aboard the craft caused one of the attitude control thrusters to fire for 11 minutes, using up its fuel supply and causing Clementine to spin at 80 rpm. Under these conditions, the asteroid flyby could not yield useful results, so the spacecraft was put into a geocentric orbit passing through the Van Allen radiation belts to test the various components on board. The mission ended in June 1994 when the power level onboard dropped to a point where the telemetry from the spacecraft was no longer intelligible.

Image of a farside moon crater Plaskett from Clementine. Credit: U.S. Geological Survey

Navigation camera image of the Moon, the solar corona on the lunar horizon, and the planet Venus. Credit: NASA/U.S. Geological Survey

© 2026, Andrew Mirecki

25 January 2004

Artist's conception of Mars Exploration Rover on the surface of Mars. Credit: NASA/JPL/Cornell University/Maas Digital LLC

On January 25, 2004, the Mars Exploration Rover – B (Opportunity) landed in Meridiani Planum on the surface of Mars, embarking on a more than 14-year mission. The total distance driven by the rover was 45.16 km and the last communication with it was on June 10, 2018.

   Opportunity was launched on a heavy Delta II 7925H on July 8, 2003. The cruise phase to Mars ended on December 11, 2003, 45 days before Mars entry. The approach phase lasted from this date until martian atmospheric entry on January 25, 2004. On entry the lander and components had a mass of 827 kg and were travelling at 19,300 km/h. The aeroshell decelerated the lander in the upper martian atmosphere for about four minutes to a velocity of 1600 km/h, followed by deployment of a parachute. The parachute slowed the spacecraft to about 300 km/h. A series of tones transmitted by the spacecraft during entry and after landing indicated the successful completion of each phase. Just prior to impact, at an altitude of about 100 m, retrorockets slowed the descent and airbags inflated to cushion the impact. The craft hit at roughly 50 km/h and bounced and rolled along the surface, stopping in a small crater. The airbags deflated and retracted, the petals opened, and the rover deployed its solar arrays. 

   The landing took place at 04:54:22.7 UT (05:05:26.6 UT Earth received time) or approximately 1:15 p.m. local time, about two and a half hours before Earth set at Terra Meridiani. On Mars it was the latter half of southern summer. The spacecraft came to rest in a 20 meters in diameter crater, known as Eagle, at 1.9483° S and 354.47417° E. This area now became known as the Challenger Memorial Station, in tribute to the Space Shuttle crew lost in 1986. Terra Meridiani is also known as the "Hematite Site" because it displays evidence of coarse-grained hematite, an iron-rich mineral which typically forms in water. It also appears to be one of the smoothest and therefore safest areas for a landing.

The interior of a crater, known as Eagle, surrounding the Mars Exploration Rover Opportunity at Meridiani Planum on Mars can be seen in this color image from the rover's panoramic camera. This is the darkest landing site ever visited by a spacecraft on Mars. The rim of the crater is approximately 10 meters from the rover. The crater is estimated to be 20 meters in diameter. Scientists were intrigued by the abundance of rock outcrops dispersed throughout the crater, as well as the crater's soil, which appears to be a mixture of coarse gray grains and fine reddish grains.  Data taken from the camera's near-infrared, green and blue filters were combined to create this approximate true color picture, taken on the first day of Opportunity's journey. The view is to the west-southwest of the rover. Credit: NASA/JPL/Cornell

   An egress phase took place over the first 4 days, involving deployment of the Pancam mast and high gain antenna, rover stand up, imaging and calibration, selection of proper egress path, and finally driving of the rover off the lander deck onto the martian surface. After extensive studies within Eagle, on March 22, 2004, Opportunity climbed up the edge of the crater and rolled out and headed for a new phase of its mission in Endurance Crater, about 750 meters away. After exiting Eagle, the rover took some spectacular shots of the abandoned area where the lander, backshell, and parachute were still visible.

This image taken by the panoramic camera aboard the Mars Exploration Rover Opportunity shows the rover's empty lander platform, the Challenger Memorial Station, at Meridiani Planum. The image was acquired on the rover's 24 sol, or Martian day Time. Credit: NASA/JPL-Caltech/Cornell University

   In 2005, the rover got stuck after driving into an area where several of its wheels were buried in sand. Controllers at NASA's Jet Propulsion Laboratory in Pasadena, California, were able to maneuver the vehicle a few inches at a time and to free Opportunity in June 2005 after six weeks. Through the remainder of 2005 and into 2006, the rover headed slowly south toward Victoria crater, first arriving at Erebus, a highly eroded impact crater about 300 meters in diameter. After a 21-month trip, Opportunity finally arrived at Victoria, a crater that stretches 800 meters in diameter, in September 2006 and sent back striking pictures of its rim. On Sept. 11, 2007, the rover entered Victoria Crater, staying inside for almost a year and sending back a wealth of information on its soil. Opportunity’s next target was the enormous Endeavour Crater, about 22 kilometers in diameter. After a journey of nearly three years and about 21 kilometers, Opportunity arrived at Endeavour crater on August 9, 2011. Since then, Opportunity has continued to explore the western rim of the Endeavour Crater.

   Opportunity explored Meridiani Terra, returning images and data from its scientific instruments, for over 14 years. The final communication from the rover was received on June 10, 2018, when a severe Mars-wide dust storm blanketed its location, reducing the light to just 0.002 percent of its usual level. As Opportunity relied on solar power to survive, these conditions were unbearable. Despite trying to hibernate through the storm by entering safe mode, when the storm finally abated in late 2018 the rover failed to wake up again. On February 13, 2019, NASA said it would cease attempts to contact the rover. The total distance driven by the rover was 45.16 km.

This self-portrait of NASA's Mars Exploration Rover Opportunity comes courtesy of the Sun and the rover's front hazard-avoidance camera. The dramatic snapshot of Opportunity's shadow was taken as the rover continues to move farther into "Endurance Crater." The image was taken on sol 180 (July 26, 2004). Credit: NASA/JPL

© 2026, Andrew Mirecki