NASA's Shiny New Rockets (or The Inmates are Running the Asylum)If you have been following the ongoing saga that is the current manned space program, you know that there are only ten Space Shuttle flights left. After the last shuttle flies, NASA intends to fly no human missions for at least four years while it develops its two shiny new rockets along with a bunch of old ideas made new in the form of a new Apollo-style command module, service module and lunar lander.
The Ares I is the crew launch vehicle. Initially it was supposed to be made from shuttle-derived hardware, using a four-segment space shuttle solid rocket booster as its first stage with a second stage made from putting a Space Shuttle Main Engine on what was essentially the space shuttle external tank reworked into a second stage. Atop this stack would sit the new Orion capsule — a larger Apollo-style capsule named after an old nuclear propelled spaceship design. The purpose of the Ares I is to get the Orion into low Earth orbit and to the International Space Station.
Trouble is, the Orion got fat and apparently will stay fat. The solid rocket booster was changed from a four-segment booster to a five segment booster and, recently, to a five-and-a-half segment booster. Because this is a whole new rocket configuration, drastically different than what flew on the space shuttle, $3 billion will have to be spent to develop this new first stage. So much for the savings from reusing shuttle hardware! But wait, there's more! The idea of using a Space Shuttle Main Engine as the second stage engine was tossed, mostly because the SSMEs are very expensive. NASA elected to use the J-2 engine from the second and third stages of the Apollo-era Saturn V rocket. Because Orion got fat and because NASA only wants to use a single J-2 on the second stage, they need to increase the thrust beyond what the J-2 initially had. Enter the J-2X and the $1.2 billion needed to develop the uprated engine.
All of this expense it to get a large capsule that weighs in the neighborhood of 25,000 kg (roughly 55,000 pounds) into low Earth orbit. If only we had another available launch system that could lift that kind of payload...
We do.
It is called the Boeing Delta IV Heavy. The Delta IV Heavy has flown twice. The first launch placed the payload in an improper orbit due to premature engine cutoff. This is certainly a failure, but certainly not on the order of the vehicle being destroyed in a spectacular explosion. The second flight was successful. Two more flights of the launcher are planned through the end of 2009. The Ares I will not fly in its planned 5.5 solid rocket segment version with J-2X second stage until December 2013 at the earliest.
NASA initially considered using the Delta IV Heavy to launch the Orion, but concluded that the Ares I design would be twice as safe. This was determined before the switch to the 5.5 segment solid rocket motor and the switch to the J-2X second stage. Both of these are unproven designs that simply cannot currently support the safety claim. NASA did like the RS-68 rocket engine on the Delta IV Heavy and is using it in the Ares V, which will be discussed shortly.
Serious consideration should be given to using the Delta IV Heavy to at least fly unmanned engineering flights with development Orion hardware before the Ares I becomes available. Consideration should be given to "man-rating" the Delta as well. Man-rating is in quotes because NASA throws the term around, but to my knowledge, has never defined it. There is no check list or manual that describes what man-rating is. These aren't the droids you're looking for. How much would it cost to improve the reliability of Delta systems to the point you were comfortable putting humans on board? Is it cheaper than the $4.2 billion cost of creating the 5.5 segment SRM and J-2X? I bet it is.
As I said above, one of the reasons that the Ares I has had to be redesigned is that the Orion is too heavy. In addition to trying to engineer weight out of the Orion, weight reduction on the first or second stage of the Ares I would also be a Good Thing. What if I told you there was a way to get rid of around 11,000 pounds from the first stage of the Ares I that, in addition to possibly saving development costs or even eliminating them, would reduce the operational costs of the Ares I launcher as well? How can this be? Get rid of the solid rocket motor parachute recovery system and let the first stage sink when it hits the ocean. Throw it away. While it may not be politically correct or green, it would also eliminate the idiocy of spending more to recover and refurbish SRM casings than it costs to simply build new.
Another thought: so Ares I came up short with both four and five segment solid rocket booster, so now we are looking at 5.5 segment solid rocket, right? That's 5.5 thrust producing segments and $3 billion in new development because of the higher chamber pressures. Why not reconfigure the first stage to be two mated 3 segment boosters? That would give you 6 thrust producing segments. You'll need some of the extra thrust to overcome weight gain from the structure needed to connect the two SRMs together and adapt them to carry the second stage and there will be some development work needed because we haven't flown 3 segment boosters, much less two tied together. But lower pressures should mean greater safety, no?
This also may help address the stability criticism leveled at the Ares I because of its current very long, thin design. Using two 3 segment boosters as a first stage (and killing the parachute recovery system) would shorten the vehicle considerably.
This brings us to the Ares V. The purpose of the Ares V is to be a heavy lift rocket. It is to carry the Earth Departure Stage and the Altair Lunar Lander into orbit. Once on orbit, an Orion launched by an Ares I docks with the Earth Departure Stage and the whole newly joined stack rockets off to the moon.
As you may suspect, the Ares V design has also undergone considerable revision. The initial design used five Space Shuttle Main Engines in the first stage. This proved too costly and five RS-68 engines from the Delta IV program were substituted. As payload weight gains became more of a concern, a sixth RS-68 was added to the first stage and the first stage was lengthened to accommodate extra propellants. This makes the completed vehicle taller than the Vehicle Assembly Building at Cape Kennedy, but that's all right. Massive facilities reworking has to happen anyway at great expense because the 5.5 segment solid rocket boosters used on both Ares I and Ares V can't be lifted without uprated cranes at the VAB and the empty weight of the current-design Ares V exceeds what the crawler-transporters can move to the launch pad. NASA plans to fire the money cannon at all of these problems.
A couple of thoughts: the Ares V design uses two of the 5.5 segment solid rocket boosters, giving a total of 11 segments. What if we changed that to three 4 segment boosters of the kind the Space Shuttle has used successfully 120 times? That would give us 12 segments producing thrust, with some extra margin to cover weight increases caused by needing to support a third solid rocket. There would be no development costs for the 4 segment booster, just the costs needed to attach three of them to the core vehicle and determine the associated loads and limits. The weight of this beast would still probably necessitate the already contemplated crawler-transporter and crane changes/replacements, but at least we wouldn't have to raise the roof on the VAB.
As for the first stage Ares V core, at what point does simply adding RS-68s not make sense? NASA built the first stage of the Saturn V around the F-1 engine, the largest liquid-fueled rocket engine ever flown. An uprated F-1A was even contemplated back in the Apollo era. I know there is a whole cadre of folks who worship at the foot of the F-1 — maybe some time should be spent checking to see if they aren't on to something?
The second stage of the Ares V (the Earth Departure Stage) was supposed to be a single SSME in the initial design, but that got switched to the J-2X when the SSME costs were factored in. The J-2X is to have a thrust of 294,000 pounds. The original Saturn J-2 had a thrust of 200,000 pounds. Instead of spending $1.2 billion to improve the thrust 47%, why not mount a second J-2 on the stage, providing 400,000 pounds of thrust and potentially life-saving redundancy? Sure there is some weight penalty and an increase in failure modes (two things to break instead of one), but I'm thinking our three 4 segment solids bought us some margin.
Clearly much of what NASA is saying and doing with the Ares I and Ares V doesn't make a lot of sense. Like all too much of the current president's portfolio, this too will be dumped into the next president's lap. The Direct proposal, put together by lots of folks smarter than me, takes a different cut at all of this and probably is the way to go — or would be if so much time and energy hadn't already been wasted on the current designs.
Labels: space
