Miscellaneous Rocket Data to Mars

This article is one of 5 posted this date,  dealing with the abilities and the cost-effectiveness of 7 launch vehicles for delivering payloads to the surface of Mars.  4 of these articles provide the details for where the numbers came from,  1 provides the comparison among the all 7 launchers considered.  

This article is a data sources and details article.

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For the Delta-IV Heavy,  I found "8000 kg to TMI" per wikipedia as of 8-31-2018. This matches with the 8 metric tons for Mars missions shown for "existing launch vehicles" in the NASA Mission Planner's Guide for SLS (Reference 1).  The largest payloads among existing vehicles are carried by Delta-IV Heavy,  if one excludes Falcon-9 and Falcon-Heavy.  I also had a launch price for Delta-IV Heavy of $400M,  in reference 2. Here "TMI" means "trans-Mars injection",  presumably a min-energy Hohmann transfer orbit from Earth to Mars.

I found online a Popular Science magazine article.  I found it 8-31-2018.  It says "max 11,000 pounds to Mars for Atlas V",  without specifying the Atlas V configuration.  That 11,000 pound figure converts to 4.99 metric tons. The Atlas V user's Manual 2010 (available on-line) gave no guidance for missions outside Earth orbit. However,  that figure of just under 5 tons is fairly realistic for an Atlas V 500-series configuration,  so I used it here as "in the ballpark".  I had a launch price of $153M in reference 2 for an Atlas V 551 configuration.  I used this with the payload figure as an "in the ballpark" realistic estimate for a Mars launch with a 551 configuration.

Both vehicles fly their payloads within a shroud.  Per the methods used in reference 1,  I used the same 10% deduction from thrown mass for the payload adapter,  and the same 50% payload/ignition fraction for the direct-entry lander.  This presumes a direct entry from the interplanetary trajectory,  with a craft of fairly large ballistic coefficient,  so that chutes are infeasible because the altitudes are too low and timelines too short.  Under these circumstances,  retro-propulsion from the end of hypersonics (about 0.7 km/s) is required for a safe touchdown.  That retro-propulsion technology is flying operationally,  while extendible or inflatable heat shields that reduce ballistic coefficient are not yet flying,  except very experimentally.

Results follow:



vehicle................thrown mass...$M/launch..net payload..useful..$M/u.ton
............................to TMI m.ton.....................entry m.ton..m.ton... 
Delta-IV Heavy...8.000..............400.............7.20..............3.60.....111
Atlas-V 551.........4.99................153.............4.491............2.245...68



Note that m.ton means metric ton,  net payload is the mass at entry and at ignition for the lander,  and 50% of that lander mass is the useful payload delivered to the surface of Mars. Note also that these numbers are inherently imprecise,  but not by factors of 2 or more.

References:

1. 2014 Mission Planner's Guide released by NASA,  available on-line as file SLS_Mission_Planners_Guide_Ver1_Aug2014.pdf

2. Article dated Feb 9, 2018 titled "Launch Costs Comparison 2018" posted here at http://exrocketman.blogspot.com