Thursday, November 5, 2009

Ares vs the Sidemount and the Augustine Commission

by Marcel F. Williams

During Space Shuttle manager John Shannon's presentation of the Side-mount Shuttle (SD-HLV) concept to the Augustine Committee, he showed the committee figures that indicated that a SD-HLV with an EDS (Earth Departure Stage) could place approximately 39 tonnes of net payload into lunar orbit per launch. However, just a week later, a subsequent, more thoroughly analyzed NASA study, indicated that up to 47.8 tonnes of net payload could be placed into lunar orbit per SD-HLV launch with an EDS.

Unfortunately, in the Augustine commission's final report, a SD-HLV architecture that could only deliver 39 tonnes to lunar orbit was presented to the President. And this lower mass estimate led to the following conclusion by the committee:

"Among the other notable differences between the Ares V family and the more-directly Shuttle-derived launcher family is the mission-launch reliability. Since the latter requires three launches for each planned Constellation lunar mission,there would be a somewhat lower reliability in any given time window than would be provided by the Ares V, which only would require two launches in the same time window."

  • Single launch plus EDS stage
  • Net payload to lunar orbit:
  • 47.8 tonnes
  • Net payload to LEO:
  • 100.8 tonnes
  • Maximum Altair lunar lander mass:
  • 47.8 tonnes
  • Maximum Orion mass plus EDS payload to lunar orbit:
  • 22 tonne Orion plus 25.8 tonnes of EDS net payload
Credit NASA

This is clearly an erroneous conclusion by the Augustine Committee since a single SD-HLV/EDS launch can deliver a full sized Altair vehicle (45 tonnes plus) to lunar orbit, while a second SD-HLV/EDS launch could deliver an Orion vehicle plus at least an equal mass of additional payload to lunar orbit. So if anything, a two launch SD-HLV scenario (47.8 tonnes plus 47.8 tonnes) would exceed the two launch Ares I/V scenario (22 tonnes plus 49 tonnes) in total mass delivered to lunar orbit. In fact, a single SD-HLV/EDS launch could, in theory, deliver a 22 tonne Orion vehicle into lunar orbit plus a 25 tonne lunar landing vehicle (more than 50% more massive than the 16 tonne lunar module of the Apollo era).

  • Ares I/V dual launch configuration to lunar orbit
  • 22 tonne Orion plus up to 49 tonne Altair lunar landing mass
  • Ares I
  • 25 tonnes to LEO
  • Ares V:
  • 188 tonnes to LEO

Credit NASA

NASA also concluded that an SD-HLV plus EDS stage could be developed in just 66 months at an estimated cost of $9.4B which is dramatically lower than NASA's estimated cost for the development of the Ares I/V which they conclude would cost over $30 billion. (Neither of these figures include the developmental cost of the Orion and Altair vehicles.)

The committee also made an obvious conclusion about the SD-HLV concept vs. the inline shuttle derived concept (DIRECT):

"While the Committee did not examine the technical trade between the side-mount and inline variants in detail, it observes that the side-mount variant is considered an in-herently less safe arrangement if crew are to be carried, and is more limited in its growth potential. "

However, they also noted the following:

"Historically, vehicles with heritage derived from prior demonstrated systems have shown greater reliability in early usage than newly developed systems. The process of converting an established cargo launcher into a human-rated launcher results in improved reliability, as was demonstrated in the early U.S. human spaceflight programs where modified ICBMs were employed as launch systems. History has shown that the early flight period is of much higher risk than would be expected later in flight history."

The Augustine Commission declared the current Space Shuttle as the most reliable U.S. heavy-lift vehicle ever built, judging the Titan HLV and Delta IV heavy as less reliable heavy lift vehicles. Since the DIRECT concept's Jupiter rocket would be a brand new booster, this would make the DIRECT Jupiter rocket a less reliable launch vehicle than the SD-HLV-- at least in its early stages. The DIRECT concept also requires 18 new technological developmental starts while the SD-HLV requires only 8; Ares I/V requires 35 total developmental starts.

If the Obama administration wisely decides to terminate the development of the Ares I/V configuration in favor of the SD-HLV-- while also adding $3 billion additional dollars to the NASA annual budget, NASA should have enough money to continue Space Shuttle flights until the Orion CEV and SD-HLV are ready for flight. NASA is currently spending more than $3.5 billion on Constellation development programs; that should be plenty for the Orion and related program integration and operations development. And the additional $3 billion a year should be plenty of money to develop the SD-HLV ($6.9 billion), EDS ($2.5 billion), and Altair ($4.2 billion) over the next 6 years. Plus any delays and additional cost in developing this space architecture could be easily met by the annual $6.5 billion NASA budget solely dedicate towards developing the SD-HLV, EDS, Orion, and Altair. That's up to $32.5 billion in additional funds if it takes NASA all the way to 2020 to finish the new space architecture. Once the new launch architecture is completed and the Space Shuttle program finally retired and we're back on the Moon setting up permanent modular settlements, NASA is going to have several billion dollars a year in surplus funding on its hands-- perhaps to utilize in developing the next space architecture to get us to Mars!

Links and References

1. NASA Sidemount Shuttle Report June 25, 2009,0,7079469.htmlpage

2. NASA Sidemount Shuttle Report June 17, 2009

3. Augustine Commission Final Report

4. Daily Kos Poll (Which nation will be first to establish a permanent base on the Moon?)


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Marcel F. Williams said...

Thank you!

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Anonymous said...


Its interesting that the Commission tallied safety by counting things that could go wrong. For example, an SDLV upper stage with 6 RL-10 engines was judged less safe for Loss of Mission and Loss of Crew than the same upper stage with a single JX-2 because there were six engines that could fail instead of one. It seems to me that having a single RL-10 engine fail (and get shut down by the flight software) is much less of a problem than if the single J2-X engine failed.

Similar logic lead to the conclusion that Ares I is safer because it has a single first stage engine than the SD-HLV with three engines, although it is known that the Shuttle can abort to orbit with one of its three engines failing in flight.

Just some of the puzzlements in the Final Report. More at



Marcel F. Williams said...

I absolutely agree with you Dave.

A booster with multiple engines is inherently safer than a booster with a single engine since the other engines can usually compensate for the lack of thrust if one of the engines should fail.

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Ares Download 2012 said...

This is beautifull to see! Nasa practices always amazed me to some kind of degree. I love how technology keeps expanding. I bet those people had a blast watching it from a close range. Keep on doing the good work guys!

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