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Rocketdoc Notes – Week of November 29, 2020 What should we do with NASA’s Space Launch System (SLS)

This week I thought I would cover the history and probable future of NASA’s Space Launch System (SLS) often referred to as the Senate Launch System since the overall program and design was dictated by the Alabama contingent of the U.S. Senate. The SLS is a super heavy-lift expendable launch vehicle which has been under development by NASA ever since it replaced the Ares V launch vehicle in 2011. The goal of both the SLS and the Ares V was to launch future Lunar and Mars human exploration hardware. The Ares V vehicle was part of NASA’s Constellation Program started during the Bush Administration. I worked on several Constellation NASA exploration contracts from 2005 thru 2010, but when Obama became President in 2009 NASA got refocused on Earth Sciences and Global Warming and the Constellation Program was cancelled.

In order to save jobs, both at NASA, and at key contractors, the NASA Authorization Act of 2010 was passed to enable the building of single launch vehicle usable for both crew and cargo as a replacement for the retiring Space Shuttle. That was well and good, but instead of embracing all the new technologies developed during the 1990s and 2000s the Senate went with an old Shuttle-Derived launch vehicle design from the 1980s. Figure 1 below is artwork from Boeing’s 1987 Advanced Launch System (ALS) proposal to the USAF and NASA to better understand this statement.

Figure 1 – Technology Advancement Proposed for ALS in 1987

In Figure 1 we are comparing a 1980s business-as-usual Shuttle-Derived Vehicle (SDV) on the left to our proposed ALS configuration on the right which offered an order of magnitude improvement in safety, reliability, and launch cost. As you can see, the SDV on the left is virtually identical to the current SLS. Unfortunately, the Soviet Union fell about the time the ALS program was getting started so the program was cancelled before any hardware was built. A few of the technologies planned for ALS have made it into the SLS, so reliability has improved, but there are still the safety concerns with solid rocket motors and there are no reusable components on SLS so launch costs are through the roof. How did we end up with a 1980s launch vehicle design in 2010? I wish I knew, but I suspect the Senators from Alabama grabbed an old presentation they had in a drawer and said, “here use this, it will keep all your current contractors alive”. A newer ALS-type design would have excluded the SRMs provider, ATK, a major shuttle contractor.

I support the idea of keeping NASA JSC alive with a new human crew vehicle and NASA MSFC alive with a new launch system, but why couldn’t they have moved the bar up a bit with a lifting body human crew vehicle and a partially reusable launch vehicle. In a few years both Orion and SLS will have priced themselves out of existence, and this is after we will have spent some $50 B on the two by 2024. See reference 1. Unfortunately, both Orion and SLS are designed with old dated technologies and will not be competitive with the newer systems offered by Space-X and Blue Origin. As for the Artemis Program winners, Dynetics is only working on a lunar lander where they should be competitive, but they are not a player in launch systems or crew vehicles.

If the SLS isn’t ready to fly until late 2021 and the Space-X Starship and the Blue Origin New Glenn fly before SLS there is a chance that the SLS might never fly but be cancelled. NASA doesn’t like to be embarrassed (that’s the reason the X-33 and X-34 Reusable Launch Vehicles never flew). Remember the Starship can fly for about $12 M per flight and has one and a half times the SLS’s payload capability to LEO so it’s very hard to justify SLS’s almost $2B cost per flight.

Either way we are going to finally get back to the moon, but it would be nice to make the process cost effective.

Thanks for reading.

Dana Andrews

References –


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