Launch, Cruise/Approach, Entry, Landing, and Descent, Surface Operations

Pre-launch Activities 

Preparation for the mission, including pre-project planning, science definition and instrument selection, landing site selection, assembly and testing, and delivery to the launch site.

Engineers in white suits stand over a machine to assemble robotic equipment
Engineers for NASA's Mars Exploration Rover Mission are completing assembly and testing for the twin robotic geologists at JPL.
NASA/JPL/Caltech

Launch

Liftoff from Earth.

NASA's Perseverance Rover began its long journey to Mars on July 30, 2020 by successfully launching from Cape Canaveral Air Force Station on a ULA Atlas V rocket. It began its seven-month journey to the Red Planet, landing there on Feb. 18, 2021. Credits: NASA/JPL-Caltech

Cruise: The Trip to Mars

The interplanetary cruise phase is the period of travel from Earth to Mars and lasts about 200 days. The phase begins after the spacecraft separates from the rocket, soon after launch. Engineers on Earth keep close tabs on the mission during cruise. Major activities include:

  • Checking spacecraft health and maintenance
  • Monitoring and calibrating the spacecraft and its onboard subsystems and instruments
  • Performing attitude correction turns (slight spins to keep the antenna pointed toward Earth for communications, and to keep the solar panels pointed toward the Sun for power)
  • Conducting navigation activities, such as trajectory correction maneuvers, to determine and correct the flight path and train navigators before orbit insertion or atmospheric entry. The last three correction maneuvers are scheduled during approach.
  • Preparing for entry, descent, and landing (EDL) and surface operations, a process which includes tests of communications, including the communications to be used during EDL.

The mission is timed for launch when Earth and Mars are in good positions relative to each other for landing on Mars. That is, it takes less power to travel to Mars at this time, compared to other times when Earth and Mars are in different positions in their orbits. As Earth and Mars orbit the Sun at different speeds and distances, about once every 26 months they are aligned in a way that allows the most energy-efficient trip to Mars.

Animation of the Mars Perseverance rover’s cruise phase post separation for the rocket. Credits: NASA/JPL-Caltech

Orbiter’s Journey

Approach

The approach phase begins two months prior to Mars orbit insertion.

Illustration of the Mars Reconnaissance Orbiter’s approach phase to Mars orbit insertion.
Illustration of the Mars Reconnaissance Orbiter’s approach phase to Mars orbit insertion.
NASA/JPL-Caltech

Mars Orbit Insertion

Mars Orbit insertion is the point in the mission when a spacecraft arrives just short of Mars, firing onboard rockets to slow its speed relative to the planet, and it is captured into a long, looping orbit.

Artist's concept of Mars Odyssey’s orbit insertion at Mars.
Artist's concept of Mars Odyssey’s orbit insertion at Mars.
NASA/JPL-Caltech

Aerobreaking

Aerobraking is a spaceflight technique wherein an orbiting spacecraft brushes against the top of a planetary atmosphere. The friction of the atmosphere against the surface of the spacecraft slows down and lowers the craft's orbital altitude. The solar panels are used to provide the maximum drag in a symmetrical position that allows some control as the spacecraft passes through the atmosphere. 

Instead of using onboard jets and propellant to adjust a spacecraft's orbit, aerobraking uses the atmosphere as both a brake and a steering wheel. The technique, however, shares more elements with sailing than with driving: successful aerobraking depends upon precise navigation, knowledge of weather, and a solid understanding of the forces the craft can withstand.

NASA's Mars Reconnaissance Orbiter dips into the thin Martian atmosphere to adjust its orbit in this artist's concept illustration.
Mars Reconnaissance Orbiter, aerobraking: NASA's Mars Reconnaissance Orbiter dips into the thin Martian atmosphere to adjust its orbit in this artist's concept illustration.
NASA/JPL-Caltech

Science Operations

Orbiters begin their primary science phase when they enter science orbit and their instruments and other systems are calibrated and ready to collect science data.

A crater in the ground on Mars
Crisp Crater in Sirenum Fossae: This impact crater appears relatively recent as it has a sharp rim and well-preserved ejecta, the material thrown out of the crater when a meteorite hit Mars. The steep inner slopes are carved by gullies and include possible recurring slope lineae (known as RSL) on the equator-facing slopes. RSL could be a sign that water, its freezing point lowered by a high concentration of salt, could be seeping down these steep slopes. MRO has seen RSL appear in warmer seasons and disappear in cooler seasons in a few locations on Mars, indicating a planet with plenty of active processes.
NASA/JPL-Caltech/University of Arizona

Communications Relay

At the end of their primary missions, orbiters support the Mars Exploration Program by providing communications support to future Mars missions during approach, navigation, and relay. The relay orbit is similar to that of the primary science orbit. In general, this orbit allows for relay access to any point on Mars. Most locations on Mars will have contact opportunities once or twice per day.

Relay activities and other activities in support of newly arrived missions have highest priority during the relay phase. Electra, the navigation and telecommunications relay payload, can provide UHF coverage to Mars landers and rovers on the surface using its nadir-pointed (pointed straight down at the surface) antenna.

Artists concept of communications relay supporting other Mars missions.
Artists concept of communications relay supporting other Mars missions.
NASA/JPL-Caltech

Rover/Lander’s Journey

Approach

To ensure a successful entry, descent, and landing, engineers began intensive preparations during the approach phase, about 45 days before the spacecraft entered the Martian atmosphere. It lasted until the spacecraft entered the Martian atmosphere, which extends 2,113 miles (3,522.2 kilometers) as measured from the center of the Red Planet.

This illustration shows NASA’s Mars 2020 spacecraft carrying the Perseverance rover as it approaches Mars.
Perseverance Rover Approaching Mars: This illustration shows NASA’s Mars 2020 spacecraft carrying the Perseverance rover as it approaches Mars. Hundreds of critical events must execute perfectly and exactly on time for the rover to land on Mars safely.
NASA/JPL-Caltech

Entry, Descent, and Landing

Entry, Descent, and Landing – often referred to as "EDL" – is the shortest and most intense phase of a rover mission. It begins when the spacecraft reaches the top of the Martian atmosphere, traveling at high speeds. It ends about seven minutes later, with the rover stationary on the Martian surface. To safely go from those speeds down to zero in that short amount of time, while hitting a narrow target on the surface, requires “slamming on the brakes” in a very careful, creative, and challenging way.

NASA's Mars 2020 Perseverance mission captured thrilling footage of its rover landing in Mars' Jezero Crater on Feb. 18, 2021.  The real footage in this video was captured by several cameras that are part of the rover's entry, descent, and landing suite. The views include a camera looking down from the spacecraft's descent stage (a kind of rocket-powered jet pack that helps fly the rover to its landing site), a camera on the rover looking up at the descent stage, a camera on the top of the aeroshell (a capsule protecting the rover) looking up at that parachute, and a camera on the bottom of the rover looking down at the Martian surface. Credits: NASA/JPL-Caltech

Instrument Checks and First Drive  

After landing, when engineers first conduct tests to ensure the rover is in a "safe state."

Overhead view of the Perseverance Rover on the surface of Mars
Perseverance Is Roving on Mars: This image was taken during the first drive of NASA’s Perseverance rover on Mars on March 4, 2021. Perseverance landed on Feb. 18, 2021, and the team spent the weeks since then checking out the rover to prepare for surface operations. This image was taken by the rover’s Navigation Cameras.​
NASA/JPL-Caltech

Surface Operations

For spacecraft that land on the surface of Mars, the surface operations phase is the time when spacecraft learn about Mars through day-to-day scientific activities of the rover.

This video illustration depicts Mars InSight lander’s surface operations. Credit: NASA/JPL-Caltech