Mars atmospheric entry is the

entry Entry may refer to: *Entry, West Virginia, an unincorporated community in the United States *Entry (cards), a term used in trick-taking card-games *Entry (economics), a term in connection with markets *Entry (film), ''Entry'' (film), a 2013 Indian ...

into the

atmosphere of Mars The atmosphere of Mars is the layer of gases surrounding Mars. It is primarily composed of carbon dioxide (95%), molecular nitrogen (2.85%), and argon (2%). It also contains trace levels of water vapor, oxygen, carbon monoxide, hydrogen, and nob ...

. High velocity entry into Martian air creates a CO₂-N₂ plasma, as opposed to O₂-N₂ for Earth air.J. Louriero, et al. - "Atmospheric Entry Research at the Plasma Physics Centre"
Mars entry is affected by the radiative effects of hot CO₂ gas and Martian dust suspended in the air. Flight regimes for entry, descent, and landing systems include aerocapture, hypersonic, supersonic, and subsonic.

Overview

Thermal protection systems and atmospheric friction have been used historically to reduce most of the

kinetic energy In physics, the kinetic energy of an object is the form of energy that it possesses due to its motion. In classical mechanics, the kinetic energy of a non-rotating object of mass ''m'' traveling at a speed ''v'' is \fracmv^2.Resnick, Rober ...

that needs to be lost prior to landing, with

parachute A parachute is a device designed to slow an object's descent through an atmosphere by creating Drag (physics), drag or aerodynamic Lift (force), lift. It is primarily used to safely support people exiting aircraft at height, but also serves va ...

s and, sometimes, a final bit of retropropulsion used in the final landing. High-altitude high-velocity retropropulsion is being researched for future transport flights landing heavier cargos. For example,

Mars Pathfinder ''Mars Pathfinder'' was an American robotic spacecraft that landed a base station with a rover (space exploration), roving probe on Mars in 1997. It consisted of a Lander (spacecraft), lander, renamed the Carl Sagan Memorial Station, and a ligh ...

entered in 1997.Mars Pathfinder Atmospheric Entry Strategy - NASA
/ref> About 30 minutes prior to entry, the cruise stage and entry capsule separated. When the capsule hit the atmosphere it decelerated from about 7.3 km/s to 0.4 km/s (16,330 mph to 900 mph) over three minutes. As it descended the parachute opened to slow it down further, and soon after the heat shield was released. During entry a signal was relayed back to Earth, including

semaphore Semaphore (; ) is the use of an apparatus to create a visual signal transmitted over distance. A semaphore can be performed with devices including: fire, lights, flags, sunlight, and moving arms. Semaphores can be used for telegraphy when arra ...

signals for important events. File:Mars-Science-Laboratory-Mars-Entry-Trajectory.png, Comparison of altitude (y-axis) and velocity (x-axis) of various Mars landers File:Phoenix Lander seen from MRO during EDL2.jpg, Parachute of Phoenix lander open as it descends in the Martian atmosphere. This picture was taken by the

Mars Reconnaissance Orbiter The ''Mars Reconnaissance Orbiter'' (''MRO'') is a spacecraft designed to search for the existence of water on Mars and provide support for missions to Mars, as part of NASA's Mars Exploration Program. It was launched from Cape Canaveral on Au ...

with

HiRISE High Resolution Imaging Science Experiment is a camera on board the '' Mars Reconnaissance Orbiter'' which has been orbiting and studying Mars since 2006. The 65 kg (143 lb), US$40 million instrument was built under the direction ...

File:MSL HeatShield.jpg, MSL heat shield File:Opportunity heat shield Sol335B P2364 L456-B339R1.jpg, MER-B's discarded heat shield on the surface of Mars.

List of spacecraft

* Mars 2 (1971) – entered atmosphere but crashed *

Mars 3 Mars 3 was a robotic space probe of the Soviet Mars program, launched May 28, 1971, nine days after its twin spacecraft Mars 2. The probes were identical robotic spacecraft launched by Proton-K rockets with a Blok D upper stage, each consisti ...

(1971) – entered atmosphere, soft landed, lost after 20 seconds of data transmission from the surface *

Mars 6 Mars 6 (), also known as 3MP No.50P was a Soviet Union, Soviet spacecraft launched to explore Mars. A 3MP bus spacecraft launched as part of the Mars program, it consisted of a lander, and a coast stage with instruments to study Mars as it flew p ...

(1973) – entered atmosphere but crashed * Viking 1 (1976) – successfully landed * Viking 2 (1976) – successfully landed *

(1997) – successfully landed * Beagle 2 – lost, confirmed landed but derelict in 2015 *

MER-A ''Spirit'', also known as MER-A (Mars Exploration Rover – A) or MER-2, is a Mars robotic rover, active from 2004 to 2010. ''Spirit'' was operational on Mars for sols or 3.3 Martian years ( days; '). It was one of two rovers of NASA's Mar ...

"Spirit" – successfully landed * MER-B "Opportunity" – successfully landed *

Mars Polar Lander The Mars Polar Lander, also known as the Mars Surveyor '98 Lander, was a 290-kilogram uncrewed spacecraft lander launched by NASA on January 3, 1999, to study the soil and climate of Planum Australe, a region near the south pole on Mars. It fo ...

(lost) * Deep Space 2 (lost) * Phoenix lander – successfully landed *

Mars Science Laboratory Mars Science Laboratory (MSL) is a robotic spacecraft, robotic space probe mission to Mars launched by NASA on November 26, 2011, which successfully landed ''Curiosity (rover), Curiosity'', a Mars rover, in Gale (crater), Gale Crater on Augus ...

(''

Curiosity Curiosity (from Latin , from "careful, diligent, curious", akin to "care") is a quality related to inquisitive thinking, such as exploration, investigation, and learning, evident in humans and other animals. Curiosity helps Developmental psyc ...

'' rover) – successfully landed * Schiaparelli EDM lander (lost) *

InSight Insight is the understanding of a specific causality, cause and effect within a particular context. The term insight can have several related meanings: *a piece of information *the act or result of understanding the inner nature of things or of se ...

lander (2018) – successfully landed *

Mars 2020 Mars 2020 is a NASA mission that includes the rover ''Perseverance (rover), Perseverance'', the now-retired small robotic helicopter ''Ingenuity (helicopter), Ingenuity'', and associated delivery systems, as part of the Mars Exploration Progra ...

('' Perseverance'' rover and ''Ingenuity'' helicopter) – successfully landed *

Tianwen-1 -1 ( zh , s = 天问一号) (also referred to as TW-1) is an interplanetary mission by the China National Space Administration (CNSA) which sent a robotic spacecraft to Mars, consisting of 6 spacecraft: an orbiter, two deployable cameras, lan ...

lander and remote camera and Zhurong rover – successfully landed

Technologies

A deployable decelerator like a parachute can slow down a spacecraft after a heat shield.B. P. Smith, et al. - A Historical Review of Inflatable Aerodynamic Decelerator Technology Development
Typically a Disk-Gap-Band parachute has been used, but another possibility are trailing or attached inflatable entry devices. Inflatable types include ''sphere w/ fence'', ''teardrop w/ fence'', ''isotensoid'', ''torus'', or ''tension cone'' and attached types include ''isotensoid'', ''tension cone'', and ''stacked toroid blunted cone''. Viking Program era researchers were the true pioneers of this technology, and development had to be restarted after decades of neglect. Those latest studies have shown that ''tension cone'', ''isotensoid'', and ''stacked torus'' may be the best types to pursue.

Finland Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...

's MetNet probe may use an expandable entry shield if it is sent. Martian air can also be used for aerobraking to orbital velocity (

aerocapture Aerocapture is an Orbital maneuver, orbital transfer maneuver in which a spacecraft uses aerodynamic drag force from a single pass through a planetary atmosphere to decelerate and achieve orbit insertion. Aerocapture uses a planet's or moon's at ...

), rather than descent and landing. Supersonic retro-propulsion is another concept to shed velocity. NASA is carrying out research on retropropulsive deceleration technologies to develop new approaches to Mars atmospheric entry. A key problem with propulsive techniques is handling the fluid flow problems and attitude control of the descent vehicle during the supersonic retropropulsion phase of the entry and deceleration. More specifically, NASA is carrying out

thermal imaging Infrared thermography (IRT), thermal video or thermal imaging, is a process where a thermal camera captures and creates an image of an object by using infrared radiation emitted from the object in a process, which are examples of infrared im ...

infrared sensor data-gathering studies of the

SpaceX Space Exploration Technologies Corp., commonly referred to as SpaceX, is an America, American space technology company headquartered at the SpaceX Starbase, Starbase development site in Starbase, Texas. Since its founding in 2002, the compa ...

booster controlled-descent tests that are currently, , underway. The research team is particularly interested in the altitude range of the SpaceX "reentry burn" on the Falcon 9 Earth-entry tests as this is the "powered flight through the Mars-relevant retropulsion regime" that models Mars entry and descent conditions, although SpaceX is of course interested also in the final engine burn and lower velocity retropropulsive landing as well since that is a critical technology for their reusable booster development program which they hope to use for Mars landings in the 2020s.

Examples

Mars Science Laboratory

The following data were compiled for the

(''Curiosity'' rover) by the Entry, Descent and Landing team at the NASA's Jet Propulsion Laboratory. It provides a timeline of critical mission events that occurred on the evening of August 5 PDT (early on August 6 EDT). 675608main edl20120809-full

Curiosity's EDL team releases a timeline for mission milestones (depicted in this artist's concept) surrounding the landing of the Mars rover.

Landing site identification

Concept art of a Mars lander as it approaches the surface, illustrating how identifying a safe landing spot is a concern. S91 25383marslanding

Overview

List of spacecraft

Technologies

Examples

Mars Science Laboratory

Landing site identification

See also

References

Further reading