The Jet Propulsion Laboratory made adjustments to the orbits of its two active satellites around Mars, Mars Reconnaissance Orbiter and Mars Odyssey, and the European Space Agency similarly adjusted the orbit of its Mars Express spacecraft to be in the right place on May 25, 2008 to observe Phoenix as it entered the atmosphere and then landed on the surface.
This information helps designers to improve future landers.
The projected landing area was an ellipse 100 km by 20 km covering terrain which has been informally named "Green Valley" and contains the largest concentration of water ice outside the poles.

Phoenix entered the Martian atmosphere at nearly 21,000 km (13,000 mi) per hour, and within 7 minutes had decreased its speed to 8 kilometers per hour (5.0 mph) before touching down on the surface.
Confirmation of atmospheric entry was received at 4:46 p.m. PDT (23:46 UTC).
Radio signals received at 4:53:44 p.m. PDT confirmed that Phoenix had survived its difficult descent and landed 15 minutes earlier, thus completing a 680 million km (422 million miles) flight from Earth.

For unknown reasons, the parachute was deployed about 7 seconds later than expected, leading to a landing position some 25–28 km east, near the edge of the predicted 99% landing ellipse.

Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE) camera photographed Phoenix suspended from its parachute during its descent through the Martian atmosphere.
This marked the first time ever one spacecraft photographed another in the act of landing on a planet (the Moon not being a planet, but a satellite).
The same camera also imaged Phoenix on the surface with enough resolution to distinguish the lander and its two solar cell arrays.
Ground controllers used Doppler tracking data from Odyssey and Mars Reconnaissance Orbiter to determine the lander's precise location as 68.218830°N 234.250778°E.
Phoenix landed in the Green Valley of Vastitas Borealis on May 25, 2008, in the late Martian northern hemisphere spring (Lₛ=76.73), where the Sun shone on its solar panels the whole Martian day.
By the Martian northern Summer solstice (June 25, 2008), the Sun appeared at its maximum elevation of 47.0 degrees.
Phoenix experienced its first sunset at the start of September 2008.

The landing was made on a flat surface, with the lander reporting only 0.3 degrees of tilt.
Just before landing, the craft used its thrusters to orient its solar panels along an east-west axis to maximize power generation.
The lander waited 15 minutes before opening its solar panels, to allow dust to settle.
The first images from the lander became available around 7:00 p.m. PDT (2008-05-26 02:00 UTC).
The images show a surface strewn with pebbles and incised with small troughs into polygons about 5 m across and 10 cm high, with the expected absence of large rocks and hills.

Like the 1970s era Viking spacecraft, Phoenix used retrorockets for its final descent.
Experiments conducted by Nilton Renno, mission co-investigator from the University of Michigan, and his students have investigated how much surface dust would be kicked up on landing.
Researchers at Tufts University, led by co-investigator Sam Kounaves, conducted additional in-depth experiments to identify the extent of the ammonia contamination from the hydrazine propellant and its possible effects on the chemistry experiments.
In 2007, a report to the American Astronomical Society by Washington State University professor Dirk Schulze-Makuch, suggested that Mars might harbor peroxide-based life forms which the Viking landers failed to detect because of the unexpected chemistry.
The hypothesis was proposed long after any modifications to Phoenix could be made.
One of the Phoenix mission investigators, NASA astrobiologist Chris McKay, stated that the report "piqued his interest" and that ways to test the hypothesis with Phoenix's instruments would be sought.
The Jet Propulsion Laboratory made adjustments to the orbits of its two active satellites around Mars, Mars Reconnaissance Orbiter and Mars Odyssey, and the European Space Agency similarly adjusted the orbit of its Mars Express spacecraft to be in the right place on May 25, 2008 to observe Phoenix as it entered the atmosphere and then landed on the surface. This information helps designers to improve future landers. The projected landing area was an ellipse 100 km by 20 km covering terrain which has been informally named "Green Valley" and contains the largest concentration of water ice outside the poles.
Phoenix entered the Martian atmosphere at nearly 21,000 km (13,000 mi) per hour, and within 7 minutes had decreased its speed to 8 kilometers per hour (5.0 mph) before touching down on the surface. Confirmation of atmospheric entry was received at 4:46 p.m. PDT (23:46 UTC). Radio signals received at 4:53:44 p.m. PDT confirmed that Phoenix had survived its difficult descent and landed 15 minutes earlier, thus completing a 680 million km (422 million miles) flight from Earth.
For unknown reasons, the parachute was deployed about 7 seconds later than expected, leading to a landing position some 25–28 km east, near the edge of the predicted 99% landing ellipse.
Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE) camera photographed Phoenix suspended from its parachute during its descent through the Martian atmosphere. This marked the first time ever one spacecraft photographed another in the act of landing on a planet (the Moon not being a planet, but a satellite). The same camera also imaged Phoenix on the surface with enough resolution to distinguish the lander and its two solar cell arrays. Ground controllers used Doppler tracking data from Odyssey and Mars Reconnaissance Orbiter to determine the lander's precise location as 68.218830°N 234.250778°E.
Phoenix landed in the Green Valley of Vastitas Borealis on May 25, 2008, in the late Martian northern hemisphere spring (Lₛ=76.73), where the Sun shone on its solar panels the whole Martian day. By the Martian northern Summer solstice (June 25, 2008), the Sun appeared at its maximum elevation of 47.0 degrees. Phoenix experienced its first sunset at the start of September 2008.
The landing was made on a flat surface, with the lander reporting only 0.3 degrees of tilt. Just before landing, the craft used its thrusters to orient its solar panels along an east-west axis to maximize power generation. The lander waited 15 minutes before opening its solar panels, to allow dust to settle. The first images from the lander became available around 7:00 p.m. PDT (2008-05-26 02:00 UTC). The images show a surface strewn with pebbles and incised with small troughs into polygons about 5 m across and 10 cm high, with the expected absence of large rocks and hills.
Like the 1970s era Viking spacecraft, Phoenix used retrorockets for its final descent. Experiments conducted by Nilton Renno, mission co-investigator from the University of Michigan, and his students have investigated how much surface dust would be kicked up on landing. Researchers at Tufts University, led by co-investigator Sam Kounaves, conducted additional in-depth experiments to identify the extent of the ammonia contamination from the hydrazine propellant and its possible effects on the chemistry experiments. In 2007, a report to the American Astronomical Society by Washington State University professor Dirk Schulze-Makuch, suggested that Mars might harbor peroxide-based life forms which the Viking landers failed to detect because of the unexpected chemistry. The hypothesis was proposed long after any modifications to Phoenix could be made. One of the Phoenix mission investigators, NASA astrobiologist Chris McKay, stated that the report "piqued his interest" and that ways to test the hypothesis with Phoenix's instruments would be sought.
Phoenix (spacecraft)