NASA To Evaluate Non-recoverable First Stage for Ares I Launch Vehicle

By Keith Cowing
December 4, 2006
Filed under
NASA To Evaluate Non-recoverable First Stage for Ares I Launch Vehicle

Some of the people working on the design of NASA’s new Ares I launch vehicle want to delete the requirement to recover and reuse the rocket’s first stage. The reason: the weight of hardware required to make recovery possible – and practical.

One of the main attributes of the current Ares I design is the use of a Solid Rocket Booster (SRB) – one that has a common heritage with proven hardware from the Space Shuttle program. This commonality and reliability is regularly touted as one of the Ares I’s current advantages over other possible launch systems.

Moreover, the 5 segment SRB that will comprise the first stage of the Ares I (the Shuttle uses a 4 segment SRB) is slated to be used – in tandem – as part of the larger Ares V launch vehicle. That dual use in both of these new launch vehicles is also cited as one of its inherent benefits.

Of course, one of the attributes cited (at least initially) in the design of the Space Shuttle is the reusability of the SRBs. This is also cited in the costs associated with Ares I and Ares V.

However, NASA sources report that a formal, internal process to change some requirements has been initiated during the on-going requirements definition process for the Ares I. If implemented by NASA this requirements change would delete the recovery and reusability of the Ares I first stage altogether.

In making this recommendation, this requirements change request cites the fact that somewhere between 20,000 and 25,000 pounds of weight could be saved in the design of the first stage by removing the systems needed to allow it to be recovered after it has been used.

Cutting this weight would offer a substantial increase in the payload that the Ares I is capable of lofting – as well as what the Ares V is capable of delivering to orbit as well.

Wind tunnel analysis has shown that the flight path that the first stage of the Ares I would fly is higher and more energetic than the one flown by the current 4 segment Space Shuttle SRBs. Some modifications (i.e. additional weight) have already had to be made in existing SRB systems to accommodate this somewhat more extreme flight profile.

Of course, there is nothing inherently wrong with an expendable launch system at all. Rather, the implications of this suggestion have to do with the economics and operations of a disposable first stage – implications that have not been factored into the Ares I program. Instead of reusing segments, new ones would have to be purchased and shipped for every Ares I flight, driving up costs.

And if the design of the Ares I first stage is still to have commonality with the future Ares V launch vehicle, then this non-recovery/non-reuse will factor into the Ares V system design as well.

While NASA has publicly and internally denied reports that the Ares I has any problem with regard to its ability to loft the Crew Exploration Vehicle (as noted in this article), many people familiar with the ongoing design process are not nearly as confident. Indeed, some are clearly worried.

This proposal to change requirements is only an observation – and a suggestion – and the Ares I program does not have to accept it. However, the fact that people working on the Ares I program see the need to cut the vehicle’s weight – and offer such a radical departure from the current design – suggests that its performance is still a concern.

Update: when I asked ESMD Associate Administrator Scott Horowitz about this issue today he replied that the Ares I first stage will be recoverable.

Reader note: In your article, NASA To Evaluate Non-recoverable First Stage for Ares I Launch Vehicle”, you forgot to mention a that recovery was one of the primary reasons that the SRM/SRB in the Ares I was “suppose” to be safer. Section 6.8.9 “Additional RSRB Safety Considerations” of the ESAS lists all the “reasons”. This was one of the primary pillars that the use of the SRB for CLV was based on. If the SRB is not recovered, then the whole debate for its use in the CLV should be revisited. Side note. The company that made the casings is out of business and the capability/infrastucture to make single billet casing is loss and would need to be redone.

SpaceRef co-founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.