The Ares 1-X test flight: crunch time for Constellation
by Taylor Dinerman
|The Ares 1-X test, now scheduled for sometime in August, will show that some of the elements of the new launch system work in the real world.|
In the world of aviation moving from one model of an existing aircraft to an improved or highly modified type can be expensive and frustrating. Lockheed Martin found this out when they went from the C-130H version of the famous Hercules transport to the C-130J. After years of delays and cost overruns the new “J” model is a big success and will probably keep the “Herc” in production for at least another decade: not bad for a plane that first flew in the mid-1950s. If the shuttle-derived hardware for the Ares works, it may stay in production for perhaps another thirty years. That’s a good reason to get make sure everything is as reliable and as cost effective as US industry can make it.
The Ares 1-X test, now scheduled for sometime in August, will show that some of the elements of the new launch system work in the real world. Even if everything goes as planned, though, this test will not provide definitive proof that this booster is the right answer to NASA’s needs. It will, however, be a big step in that direction and should not be discounted just because not all of the elements of the future operational vehicle have been tested.
Missing will be the all-up new booster with its new 12-vane interior configuration. This is the most critical change from the well-understood SRB to the new five-segment version. The need to go from 11 vanes to 12 is driven by the need to keep the burn time the same and the new requirement for more thrust. The extra vanes provide more burning surface and thus more combustion. To cope with this the Ares 1 will have a new nozzle throat.
Since NASA and its contractors do not yet have a full up five-segment system to test they are putting a fifth segment simulator on top of the four operating segments. This simulates the size and weight of the future topmost segment and houses most of the avionics and one of the external cameras.
The elements of the SRB that are not going to change and which will be tested on the upcoming test flight are the segment casing and the connecting joints. This is obviously important since that was what caused the 1986 Challenger disaster. The igniter and the propellant are, according to the contractor, virtually identical to the system used on the shuttle.
The new parts that will be tested include a forward skirt, a forward skirt extension, and the frustum, which together make up the forward assembly that attaches the five-segment booster to the Ares 1 upper stage. This is the critical element that will, hopefully, transition from the solid-fueled booster to the liquid-fueled upper stage powered by the J-2X engine that is most emphatically not being tested on this flight. Instead, an inert upper stage simulator will ride on top of the rocket stack with an Orion vehicle simulator on top of that.
Of the six primary objectives laid out by the contractor, three would seem to be of primary importance. First to “Demonstrate control of a vehicle dynamically similar to the Ares 1/Orion vehicle using Ares 1-relevant flight control algorithms.” Secondly, to “Perform an in-flight separation/staging event between an Ares 1-similar first stage and a representative upper stage.” And thirdly, to “Characterize [the] magnitude of integrated vehicle roll torque throughout first stage flight.” The other goals all fit into the category “nice to know” or “good practice.”
|If the Ares 1-X test flight fails, then the whole exploration architecture will almost certainly be sent back to the drawing board. If it succeeds it will only be one more step on a long, hard road that NASA and the contractors have to follow.|
If all goes well the Ares 1 program will not be out of the woods, as too many people have raised too many objections for one admittedly incomplete test to get them to change their minds. It will be hard to make the case that the program should go forward just on the basis of this one launch. The real case for Ares 1 was made during the 2005 Exploration Systems Architecture Study (ESAS). NASA made the decision to go for a pair of shuttle-derived launchers, Ares 1 and Ares 5. This responded to the Columbia Accident Investigation Board’s strong recommendation that crew and cargo be separately launched in any future system. It has also been claimed that the fact that the shuttle-derived elements are all human rated will increase safety and cut costs. This may be true, but NASA should make a better case for this argument than they previously have.
The most important reason why Ares 1 may be the best answer is sheer power. The Ares 1, it is claimed, will be able to lift nearly 25,000 kilograms of payload to the International Space Station. If this performance proves true, and if vehicle shows that it has the kind of reliability and on-time performance that the Russians have with their Soyuz system, then NASA will finally be able to run an Earth-to-orbit service on schedule and within budget. This, in turn, will take a lot of the pressure off the space agency, which has to constantly scramble to make its already tight budget cover the constant delays caused by various problems with the shuttle.
If the Ares 1-X test flight fails, then the whole exploration architecture will almost certainly be sent back to the drawing board. If it succeeds it will only be one more step on a long, hard road that NASA and the contractors have to follow. Already, the news has leaked out that even with the extra money in the stimulus bill, the Constellation program faces months or even years of new delays. Again, this will add to the cost and to the political vulnerability of the whole program. This is the dangerous irony of these kinds of multi-year government technology development programs: a budget cut in the early years has a cascading effect that can cripple the whole system. This is what happened to the shuttle thanks to the budget cuts it suffered in the 1970s. Ares and Constellation may not be at that stage now, but more delays and more cuts will inevitably put it in the danger zone.