Difference between revisions of "Mars mission duration"

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Manned missions to Mars split in two different types. They are named after astronomical names of the moments of departure of the ships from Mars: [[conjunction]] and opposition. Opposition type mission have less total time but more time spent travel in weightless conditions, conjunction mission have much more time spent in Mars surface.
 
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[[File:Conjunction_and_opposition_trajectory.jpg|thumb|center|1000x400px|alt=Conjunction and opposition mission trajectory.|Conjunction and opposition mission trajectory.]]
 
[[File:Conjunction_and_opposition_trajectory.jpg|thumb|center|1000x400px|alt=Conjunction and opposition mission trajectory.|Conjunction and opposition mission trajectory.]]
  
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Comparison conjunction and opposite mission type:
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Manned missions to Mars split in two different types. They are named after astronomical names of the moments of departure of the ships from Mars: [[conjunction]] and opposition. Opposition type mission have less total time but more time spent travel in weightless conditions, conjunction mission have much more time spent in Mars surface. Сonjunction and opposite mission type examples:
  
 
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[[File:Mars_oppositions.jpg|thumb|center|1000x770px|alt=Mars Oppositions from 1995 to 2007 year|Mars Oppositions from 1995 to 2007 year]]
 
[[File:Mars_oppositions.jpg|thumb|center|1000x770px|alt=Mars Oppositions from 1995 to 2007 year|Mars Oppositions from 1995 to 2007 year]]
  
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<big>Examples of the near future missions opportunities</big>
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The required parameters change at intervals of 15-17 years<ref name=Interplanetary_Mission> L.E. George, L.D. Kos - ''Interplanetary Mission Design Handbook: Earth-to-Mars Mission Opportunities and Mars-to-Earth Return Opportunities 2009-2024'' in NASA Center for AeroSpace Information July 1998; Linthicum, Maryland</ref>.
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[[File:Mars_oppositions_2012-2061.png|thumb|center|740x400px|alt=Mars oppositions from 2012 to 2061 year.|Mars oppositions from 2012 to 2061 year.]]
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<big>Examples of the near-future missions opportunities:</big>
  
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Mars short-stay (opposition) mission:
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Mars short-stay (opposition) mission
  
 
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Mars long-stay (conjunction) mission:
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Mars long-stay (conjunction) mission
  
 
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| 14-Oct-2024 || 2.62 || 0.87 years || 12.1/3.76 || 0.82 || 0.73/5.5 || 0.58/11.5
 
| 14-Oct-2024 || 2.62 || 0.87 years || 12.1/3.76 || 0.82 || 0.73/5.5 || 0.58/11.5
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For reducing crew time exposure to weightless, interplanetary radiation and the risk of being hit by solar flare it is possible to use increasing delta-V. For some of these variants it is possible to use the option of free-return trajectory - trajectory with ability return back to Earth with small amount of delta-V spending safe if the main spacecraft engine will fail to start. Options for free-return trajectories<ref name=The_Cafe_for_Mars> Robert Zubrin - ''The Case for Mars: The Plan to Settle the Red Planet and Why We Must'' in Touchstone, 1996, New York.</ref>:
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! Departure Velocity, km/s !! Orbit Period, years !! Time to Earth Return, years !! Transit to Mars, days !! Mars Aeroentry possibility
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| 3.34 || 1.5 || 3.0 || 250 || Easy
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| 5.08 || 2.0 || 2.0 || 180 || Acceptable
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| 6.93 || 3.0 || 3.0 || 140 || Dangerous
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| 7.93 || 4.0 || 4.0 || 130 || Impossible
 
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Revision as of 05:49, 1 May 2018

Conjunction and opposition mission trajectory.
Conjunction and opposition mission trajectory.

Manned missions to Mars split in two different types. They are named after astronomical names of the moments of departure of the ships from Mars: conjunction and opposition. Opposition type mission have less total time but more time spent travel in weightless conditions, conjunction mission have much more time spent in Mars surface. Сonjunction and opposite mission type examples:

Mission type [1] Total mission duration, days Earth-Mars trip, days Time spent at destination Mars-Earth trip, days Total ∆V, km/s Trans-Mars Injection, km/s Mars Orbital Insertion, km/s Trans-Earth Injection, km/s
Conjuction 1005 198 558 197 2.81 0.50 1.25 1.06
Opposition 560 177 40 342 5.69 0.61 1.75 3.33
Conjunction and opposition Mars mission duration.
Conjunction and opposition Mars mission duration comparison.

Mars have very elliptical orbit relatively to Earth. The eccentricity of the orbit of Mars is 0.0935 – second among the planets after Mercury. Launch windows to Mars opened approximately every 2.14 years (26 months) but because of Mars orbit eccentricity and differences in his orbital speed this time changes a little bit from time. The same way changes a distance between Earth and Mars in moment of oppositions, time travel to Mars and necessary for this delva-V.

Mars Oppositions from 1995 to 2007 year
Mars Oppositions from 1995 to 2007 year

The required parameters change at intervals of 15-17 years[2].

Mars oppositions from 2012 to 2061 year.
Mars oppositions from 2012 to 2061 year.

Examples of the near-future missions opportunities:

Mars short-stay (opposition) mission

Departure Date [3] Mission Duration (years) Time spent at destination Injection (C3/∆v), km/s Post-escape ∆v, km/s Destination Aerocapture (∆V/Inertial), km/s Earth Aerocapture (∆V/Inertial), km/s
19-Jul-2020 1.50 1 month 14.5/3.87 2.80 1.41/6.2 0.86/11.8
22-Oct-2021 1.39 1 month 14.4/3.86 2.80 3.48/8.2 0.47/11.4
14-Sep-2023 1.64 1 month 25.7/4.34 0.99 3.29/8.0 0.48/11.4

Mars long-stay (conjunction) mission

Departure Date [3] Mission Duration (years) Time spent at destination Injection (C3/∆v), km/s Post-escape ∆v, km/s Destination Aerocapture (∆V/Inertial), km/s Earth Aerocapture (∆V/Inertial), km/s
4-Aug-2020 2.53 1.40 years 15.7/3.92 1.45 0.70/5.5 0.80/11.7
15-Sep-2022 2.63 0.85 years 14.4/3.86 0.94 0.88/5.6 0.50/11.4
14-Oct-2024 2.62 0.87 years 12.1/3.76 0.82 0.73/5.5 0.58/11.5

For reducing crew time exposure to weightless, interplanetary radiation and the risk of being hit by solar flare it is possible to use increasing delta-V. For some of these variants it is possible to use the option of free-return trajectory - trajectory with ability return back to Earth with small amount of delta-V spending safe if the main spacecraft engine will fail to start. Options for free-return trajectories[4]:

Departure Velocity, km/s Orbit Period, years Time to Earth Return, years Transit to Mars, days Mars Aeroentry possibility
3.34 1.5 3.0 250 Easy
5.08 2.0 2.0 180 Acceptable
6.93 3.0 3.0 140 Dangerous
7.93 4.0 4.0 130 Impossible

References

  1. ↑ Bryan Mattfeld, Chel Stromgren - Trades Between Opposition and Conjunction Class Trajectories for Early Human Mission to Mars in AIAA Space 2014; 4-7 Aug. 2014; San Diego, California
  2. ↑ L.E. George, L.D. Kos - Interplanetary Mission Design Handbook: Earth-to-Mars Mission Opportunities and Mars-to-Earth Return Opportunities 2009-2024 in NASA Center for AeroSpace Information July 1998; Linthicum, Maryland
  3. ↑ 3.0 3.1 Cyrus Foster, Matthew Daniels - Mission Opportunities for Human Exploration of Nearby Planetary Bodies in AIAA SPACE 2010 Conference & Exposition, 30 August - 2 September 2010, Anaheim, California ISBN AIAA 2010-8609
  4. ↑ Robert Zubrin - The Case for Mars: The Plan to Settle the Red Planet and Why We Must in Touchstone, 1996, New York.
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