In Part 1, we looked at the pieces strewn about our living room floor. Let’s take a closer look at the Erector Set left behind by the Augustine Commission. The pieces parts are contained in Chapters 3-6.
Chapter 3.0 Goals and Future Destinations for Exploration
Most discussions concerning the Final Report have noted the importance of the having a Goal established in order to define both destinations and architectures to achieve them. Lets start with this extended quote from the Final Report:
3.1 Goals for Exploration
We explore to reach goals, not destinations. It is in the definition of our goals that decision-making for human spaceflight should begin. With goals established, questions about destinations, exploration strategies and transportation architectures can follow in a logical order. While there are certainly some aspects of the transportation system that are common to all exploration missions (e.g. crew access and heavy lift to low-Earth orbit), there is a danger of choosing destinations and architectures first. This runs the risk of getting stuck at a destination without a clear understanding of why it was chosen, which in turn can lead to uncertainty about when it is time to move on.
One can certainly agree with the rationale for starting with Goals. However, the final phrase leads one to pause. Does the expression “when it is time to move on” mean that we abandon destinations along the path toward our Goals? Rather, does it mean that we add what’s next to our collection of destinations when we have gained the required competence and experience from work on the most recent addition to our expanding list of destinations? We shall keep these questions in mind as we work through Chapter 3.
The Commission set “charting a path for human expansion into the solar system” as the Goal. The Commission sees the development of competitive commercial industries and important national capabilities as one reason for setting the Goal they did. It also cited the resulting scientific, technological, engineering and mathematical skills as another reason for choosing this Goal. Finally, the moment when we “first learn to live on another planet” will be a milestone in human history.
3.2 Overview of Destinations and Approach
Destinations can be classified by duration of the mission: the Moon is days away, the Lagrange points weeks, the near-Earth objects months, a Mars fly-by a year, and a Mars landing is the longest—about 900 days for a round trip using the most likely approach. The result of two cycles of analyses collapsed the destinations and associated missions into three candidates:
- Mars First. It is widely accepted that Mars represents the most likely candidate for a permanent expansion of human civilization beyond the Earth. Mars is unquestionably the most complex environment for exploration, and fits Dr. Steve Squyres criteria for deploying human investigators.
- Moon First. Missions to the Moon would enable the development of the operational skills and technology for landing on, launching from and working on a planetary surface.
- Flexible Path. The Commission notes that the Flexible Path option means “we must learn to operate in free space for hundreds of days, beyond the protective radiation belts of the Earth, before we can confidently commit to exploring Mars”.
The Final Report then examines each of these options.
3.3 Mars First
The possible scenarios for Mars First are two, described by the Commission this way:
Two scenarios have been developed to examine the human exploration of Mars. In the first, the surface of Mars would be the initial and only destination, and all resources would be focused on reaching it as soon as possible. In the second, systems would be designed for Mars missions, but would be first verified on several test flights to the Moon. The latter would require some hardware modification, but would test the systems at a planetary body near the Earth before committing to a multi-year mission to Mars. In the end, the Committee decided to use the variant with a brief test flight program of equipment and procedures on the Moon as the reference Mars First option.
The first scenario was analyzed based on the existing 2007 NASA Human Exploration of Mars Design Reference Architecture 5.0 (NASA-SP-2009-566 and NASA-SP-2009-566-ADD). This architecture is shown in Figure 3.3.2-1 (p. 36). Figure 3.3.2-2 shows the architecture of first conducting several missions to the Moon.
The Commission concluded that the technological problems were many, and that a decade of research was required before design work could commence. Further, the costs were significantly higher than for either of the other two options.
Clearly, either of the possible scenarios leaves little or no infrastructure in place, and fails the Goals criteria.
3.4 Moon First
The Commission next examined the Moon First. Here, the possibility of resource utilization for supplying propellant to the space around the Earth-Moon system, as well as the scientific value of exploration based on our incomplete understanding of the Moon drive two possible scenarios. The first is a Lunar Base, where a permanent station is established, most likely at the South Pole where solar energy would be available at all times. The emphasis would be on local exploration and resource utilization for propellant manufacture.
The alternate scenario was Lunar Global, where missions of from 14 to 180 days would be flown to a variety of sites, adjusting the program as discoveries were made.
Either of these programs would be supported by one of three architectures considered by the Committee:
- Constellation “1.5 launch” architecture – one Ares I with Orion, plus one Ares V with the Altair lander. This combination is Integrated Option 3 in Chapter 6.
- Ares V Lite “dual” architecture – two Ares V Lites, one with the Orion, and one with the Altair lander. This combination is Integrated Option 4A in Chapter 6.
- A more directly Shuttle-derived launcher, which requires three launches for a crew mission plus one commercial launch of crew to low-Earth orbit. This combination is Integrated Option 4B in Chapter 6.
One is immediately struck by two contradictions within these architectures. First is the requirement for three launches for the more directly Shuttle-derived launcher, when two launches of the Jupiter 246 exceed the Constellation Program requirements. See this data sheet for the Jupiter 130 Crew and Cargo (60 mt to low earth orbit) and data sheet for the Jupiter 246 Crew and Cargo launcher (96 mt to LEO and 79 mt through TLI).
The second more serious contradiction is allowing Ares V Lite to launch crew, but requiring the Shuttle-derived vehicle to only carry cargo. The problem we face is that Ares V Lite has:
- New Engines
- New External Tank (10 meters)
- New Solid Rocket Boosters (5 segment)
Each of these requires independent rating for human flight. On the other hand, both the side-mount Shuttle-derived launch vehicle and the in-line Shuttle-derived vehicle have:
- Existing SSME (Space Shuttle Main Engines)
- Existing External Tank (8.4 meters)
- Existing 4 segment Solid Rocket Boosters (SRB)
The SSMEs and the 4 segment SRBs are already human flight qualified. The modifications to the ET would require flight testing for qualification of the in-line vehicle, but are minor compare to designing and building a brand new 10 meter tank. While the side-mount Shuttle-derived launch vehicle has disadvantages for launching crew, the in-line Shuttle-derived vehicle has no such drawbacks.
These contradictions place unwarranted obstacles on the Shuttle-derived vehicles, especially the in-line version.
3.5 The Flexible Path to Mars
The Commission states:
“The goal is to take steps toward Mars, learning to live and work in free space and near planets, under the conditions humans will meet on
the way to Mars. We must learn to operate in free space for hundreds of days, beyond the protective radiation belts of the Earth, before we can confidently commit to exploring Mars.
The primary attraction of this option is that we can build increasing confidence, infrastructure and expertise as we move from one destination to the next.
There are multiple destinations. Each one offers the opportunity to build different skills. Especially valuable would be for international partners to take on the challenge of Lunar Surface Exploration while NASA continues the research and development required for the Flexible Path missions. Both commercial enterprises and International Partners could handle the propellant delivery to the depots in LEO, EML-2, and eventually Phobos. All of this is aimed at the eventual establishment of permanent human presence on Mars.
From the perspective of the Goals given by the Commission, the Flexible Path option is the strongest.
3.6 Summary of Strategies for Exploration Beyond Low-Earth Orbit
The Committee concludes as follows:
Mars is the ultimate destination for human exploration of the inner solar system; but it is not the best first destination. Both visiting the Moon First and following the Flexible Path are viable exploration strategies. The two are not necessarily mutually exclusive; before traveling to Mars, we might be well served to both extend our presence in free space and gain experience working on the lunar surface.
In the next post, we will look at the existing human space flight programs discussed in Chapter 4.0.