Mars atmospheric entry is the entry into the atmosphere of Mars. High velocity entry into Martian air creates a CO2-N2 plasma, as opposed to O2-N2 for Earth air. [1] Mars entry is affected by the radiative effects of hot CO2 gas and Martian dust suspended in the air. [2] Flight regimes for entry, descent, and landing systems include aerocapture, hypersonic, supersonic, and subsonic. [3]
Thermal protection systems and atmospheric friction have been used historically to reduce most of the kinetic energy that needs to be lost prior to landing, with parachutes 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 entered in 1997. [4] About 30 minutes prior to entry, the cruise stage and entry capsule separated. [4] 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. [4] As it descended the parachute opened to slow it down further, and soon after the heat shield was released. [4] During entry a signal was relayed back to Earth, including semaphore signals for important events. [4]
A deployable decelerator like a parachute can slow down a spacecraft after a heat shield. [5] Typically a Disk-Gap-Band parachute has been used, but another possibility are trailing or attached inflatable entry devices. [5] 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. [5] Viking Program era researchers were the true pioneers of this technology, and development had to be restarted after decades of neglect. [5] Those latest studies have shown that tension cone, isotensoid, and stacked torus may be the best types to pursue. [5]
Finland's MetNet probe may use an expandable entry shield if it is sent. [6] Martian air can also be used for aerobraking to orbital velocity (aerocapture), rather than descent and landing. [1] Supersonic retro-propulsion is another concept to shed velocity. [7]
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 sensor data-gathering studies of the SpaceX booster controlled-descent tests that are currently, as of 2014 [update] , underway. [8] The research team is particularly interested in the 70–40-kilometer (43–25 mi) 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, [9] 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. [10] [11]
The following data were compiled for the Mars Science Laboratory (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). [12]
| Event | Time of Event Occurrence at Mars (PDT) | Time Event Occurrence Received on Earth (PDT) |
|---|---|---|
| Atmospheric entry | 10:10:45.7 PM | 10:24:33.8 PM |
| Parachute deployment | 10:15:04.9 PM | 10:28:53.0 PM |
| Heat shield separation | 10:15:24.6 PM | 10:29:12.7 PM |
| Rover lowered by the sky crane | 10:17:38.6 PM | 10:31:26.7 PM |
| Touchdown | 10:17:57.3 PM | 10:31:45.4 PM |
Curiosity's EDL team releases a timeline for mission milestones (depicted in this artist's concept) surrounding the landing of the Mars rover.
Concept art of a Mars lander as it approaches the surface, illustrating how identifying a safe landing spot is a concern. [13]
Atmospheric entry is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet, or natural satellite. There are two main types of atmospheric entry: uncontrolled entry, such as the entry of astronomical objects, space debris, or bolides; and controlled entry of a spacecraft capable of being navigated or following a predetermined course. Technologies and procedures allowing the controlled atmospheric entry, descent, and landing of spacecraft are collectively termed as EDL.
The Mars 2 was an uncrewed space probe of the Mars program, a series of uncrewed Mars landers and orbiters launched by the Soviet Union beginning 19 May 1971. The Mars 2 and Mars 3 missions consisted of identical spacecraft, each with an orbiter and an attached lander. The orbiter is identical to the Venera 9 bus. The type of bus/orbiter is the 4MV. They were launched by a Proton-K heavy launch vehicle with a Blok D upper stage. The lander of Mars 2 became the first human-made object to reach the surface of Mars, although the landing system failed and the lander was lost.
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 consisting of an orbiter and an attached lander. After the Mars 2 lander crashed on the Martian surface, the Mars 3 lander became the first spacecraft to attain a soft landing on Mars, on December 2, 1971. It failed 110 seconds after landing, having transmitted only a gray image with no details. The Mars 2 orbiter and Mars 3 orbiter continued to circle Mars and transmit images back to Earth for another eight months.
Mars Pathfinder is an American robotic spacecraft that landed a base station with a roving probe on Mars in 1997. It consisted of a lander, renamed the Carl Sagan Memorial Station, and a lightweight, 10.6 kg (23 lb) wheeled robotic Mars rover named Sojourner, the first rover to operate outside the Earth–Moon system.
A lander is a spacecraft that descends towards, then comes to rest on the surface of an astronomical body other than Earth. In contrast to an impact probe, which makes a hard landing that damages or destroys the probe upon reaching the surface, a lander makes a soft landing after which the probe remains functional.
The Beagle 2 is an inoperative British Mars lander that was transported by the European Space Agency's 2003 Mars Express mission. It was intended to conduct an astrobiology mission that would have looked for evidence of past life on Mars.
NASA's Mars Exploration Rover (MER) mission was a robotic space mission involving two Mars rovers, Spirit and Opportunity, exploring the planet Mars. It began in 2003 with the launch of the two rovers to explore the Martian surface and geology; both landed on Mars at separate locations in January 2004. Both rovers far outlived their planned missions of 90 Martian solar days: MER-A Spirit was active until March 22, 2010, while MER-B Opportunity was active until June 10, 2018.
The Mars Polar Lander, also known as the Mars Surveyor '98 Lander, was a 290-kilogram robotic 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 formed part of the Mars Surveyor '98 mission. On December 3, 1999, however, after the descent phase was expected to be complete, the lander failed to reestablish communication with Earth. A post-mortem analysis determined the most likely cause of the mishap was premature termination of the engine firing prior to the lander touching the surface, causing it to strike the planet at a high velocity.
Mars Science Laboratory (MSL) is a robotic space probe mission to Mars launched by NASA on November 26, 2011, which successfully landed Curiosity, a Mars rover, in Gale Crater on August 6, 2012. The overall objectives include investigating Mars' habitability, studying its climate and geology, and collecting data for a human mission to Mars. The rover carries a variety of scientific instruments designed by an international team.
The ballute is a parachute-like braking device optimized for use at high altitudes and supersonic velocities.
An aeroshell is a rigid heat-shielded shell that helps decelerate and protects a spacecraft vehicle from pressure, heat, and possible debris created by drag during atmospheric entry. Its main components consist of a heat shield and a back shell. The heat shield absorbs heat caused by air compression in front of the spacecraft during its atmospheric entry. The back shell carries the load being delivered, along with important components such as a parachute, rocket engines, and monitoring electronics like an inertial measurement unit that monitors the orientation of the shell during parachute-slowed descent.
A Mars landing is a landing of a spacecraft on the surface of Mars. Of multiple attempted Mars landings by robotic, uncrewed spacecraft, ten have had successful soft landings. There have also been studies for a possible human mission to Mars including a landing, but none have been attempted. Soviet Union’s Mars 3, which landed in 1971, was the first successful Mars landing. As of 2023, the Soviet Union, United States and China have conducted Mars landings successfully.
A hypercone is a mechanism for atmospheric reentry deceleration proposed for use by future Mars landing missions. It is an inflatable structure combining characteristics of both heat shields and parachutes.
The SpaceX Red Dragon was a 2011–2017 concept for using an uncrewed modified SpaceX Dragon 2 for low-cost Mars lander missions to be launched using Falcon Heavy rockets.
Curiosity is a car-sized Mars rover exploring Gale crater and Mount Sharp on Mars as part of NASA's Mars Science Laboratory (MSL) mission. Curiosity was launched from Cape Canaveral (CCAFS) on November 26, 2011, at 15:02:00 UTC and landed on Aeolis Palus inside Gale crater on Mars on August 6, 2012, 05:17:57 UTC. The Bradbury Landing site was less than 2.4 km (1.5 mi) from the center of the rover's touchdown target after a 560 million km (350 million mi) journey.
Mars 2020 is a NASA mission that includes the rover Perseverance, the now-retired small robotic helicopter Ingenuity, and associated delivery systems, as part of the Mars Exploration Program. Mars 2020 was launched on an Atlas V rocket at 11:50:01 UTC on 30 July 2020, and landed in the Martian crater Jezero on 18 February 2021 with confirmation received at 20:55 UTC. On 5 March 2021, NASA named the landing site Octavia E. Butler Landing. As of 10 February 2024, Perseverance has been on Mars for 1058 sols. Ingenuity operated on Mars for 1042 sols before sustaining serious damage to its rotor blades, possibly all four, causing NASA to retire the craft on 25 January 2024.
Austere Human Missions to Mars is a concept for a human mission to Mars by the United States space agency, NASA. Released in 2009, it proposed a modified and even less costly version of Design Reference Architecture (DRA) 5.0, itself a combination of nearly 20 years of Mars planning design work. The mission profile was for a conjunction class with a long surface stay, pre-deployed cargo, aerocapture and propulsive capture, and some in-situ resource production. As of 2015, the concept had not yet been adapted to the Space Launch System that replaced NASA's Constellation program in 2011.
Schiaparelli EDM was a failed Entry, Descent, and Landing Demonstrator Module (EDM) of the ExoMars programme—a joint mission of the European Space Agency (ESA) and the Russian Space Agency Roscosmos. It was built in Italy and was intended to test technology for future soft landings on the surface of Mars. It also had a limited but focused science payload that would have measured atmospheric electricity on Mars and local meteorological conditions.
Sky crane is a soft landing system used in the last part of the entry, descent and landing (EDL) sequence developed by NASA Jet Propulsion Laboratory for its two largest Mars rovers, Curiosity and Perseverance. While previous rovers used airbags for landing, both Curiosity and Perseverance were too heavy to be landed this way. Instead, a landing system that combines parachutes and sky crane was developed. Sky crane is a platform with eight engines that lowers the rover on three nylon tethers until the soft landing.
the requirements for returning a first stage here on the Earth propulsively, and then ... the requirements for landing heavy payloads on Mars, there's a region where the two overlap—are right on top of each other ... If you start with a launch vehicle, and you want to bring it down in a controlled manner, you're going to end up operating that propulsion system in the supersonic regime at the right altitudes to give you Mars-relevant conditions.
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