Mars atmospheric entry
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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. Mars entry is effected 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.
For example Mars Pathfinder entered in 1997. About 30 minutes prior to entry, the cruise stage and entry capsule separated. When the capsule hit the atmosphere it de-accelerated from about 7.3 km/s to 0.4 km/s (16330 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 signals for important events.
- Mars 2
- Mars 3
- Mars 6
- Viking 1
- Viking 2
- Mars Pathfinder
- Phoenix lander
- Mars Science Laboratory
A deployable decelerator like a parachute can slow down a spacecraft after a heat shield. 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 show that tension cone, isotensoid, and stacked torus may be the best types to pursue.
Finland'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), rather than descent and landing. Supersonic retro-propulsion is another concept to shed velocity.
The following data were compiled by Mars Science Laboratory's Entry, Descent and Landing team at 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).
|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.
- J. Louriero, et al. - Atmospheric Entry Research at the Plasma Physics Centre
- R. M. Haberle, et al. - A boundary-layer model for Mars - Journal of the Atmospheric Sciences
- Development of Supersonic Retro-Propulsion for Future Mars Entry, Descent, and Landing Systems (.pdf)]
- Mars Pathfinder Atmospheric Entry Strategy - NASA
- B. P. Smith, et al. - A Historical Review of Inflatable Aerodynamic Decelerator Technology Development
- MetNet EDLS
- Hoppy Price - Austere Human Missions to Mars (2009) - JPL
- NASA - Timeline Mission Milestones During Curiosity's Landing