The booster we really need
I've been putting some thought into the strategic direction of the current launch vehicle fleet, and I see a niche for a new class of rocket that hasn't been fully explored. Basically, I'm thinking along the lines of the "Atlas V Phase 2." I want a bigger EELV.
With the current EELV's currently unprofitable, why should we build a bigger one? There are actually a few good reasons for doing so. For starters, manned spacecraft in the HL-20 class will weigh approximately 25 tonnes once the launch abort system is factored in. While this is within the capabilities of the current EELV-Heavy rockets, the need for parallel stages increases the risk of first stage engine failure. If a single-core rocket could boost the HL-20, it would be much safer for a human crew.
There are other benefits to a bigger EELV that can launch 25-28 tonnes in its single-core variant. The single-core booster could launch Geosynchronous-orbiting satellites and the Pentagon's polar-orbit satellites, both of which have similar energy requirements to the HL-20.
NASA's previous studies have poo-pooed the EELV's for launching manned spacecraft. They point to "highly lofted trajectories" on the upper stages that would produce heavy deceleration loads in the event of an abort. NASA also feels that the current ISS requirements for the CEV can't be met by the current Delta or Atlas. Finally, NASA strikes down the EELV's under the ill-defined hammer of "human-rating."
In response to NASA, they have a legitimate point regarding the abort loads, but they preface those comments with "single engine upper stage." Has the analysis been done for the dual-engine Centaur that is part of the Atlas V family? Also, the ISS requirement for the CEV is only a problem because NASA insists on flying the CEV to the ISS using the same service module as used on the moon missions. The CEV could get away with a much smaller service module for these missions; as Mark Wade points out, the CEV is carrying an extra 9.3 tons of propellant that will likely go to waste.
Shooting down the "human rating" requirement is as easy as shooting fish in a barrel. After all, NASA had no problem human-rating the Redstone, Atlas D, or Titan II, even though all of those missiles had been designed for hurling warheads at the commies. Obviously there will need to be trajectory modifications to limit the g-forces, and some form of vehicle performance-monitoring to activate the escape system if a failure is detected. None of these are show-stoppers, and they are much cheaper than building The Stick from scratch. Of course, the Shuttle was never really "human-rated" either. Let me refer you to the shuttle abort procedure, as taken from the shuttle pilot's manual.
1.) Place head between legs.
2.) Kiss butt goodbye.
In short, any EELV can be made safer than the shuttle. The Stick is not necessary.
My optimal solution to the issue of CEV launch is a 5-meter diameter variant of the Atlas V. This was actually addressed in the ESAS report as "Atlas Phase 2, 5.4 meter." It would (hopefully) combine the reliability, modularity, and lean pad processing of the Atlas V with the lifting abilities sought in The Stick. Furthermore, three Atlas (5-meter) cores could be strapped together to form an unmanned heavy lifter. While this rocket would have about half the capability of the shuttle-derived heavy lifter, it would be a lot cheaper to build a 5-meter Atlas than it would be to build both The Stick and the shuttle-derived heavy lifter.
The 5-Meter Atlas could be the best thing to come out of the merger of Atlas and Delta production lines. United Launch Alliance can start out with the 5 meter tooling for the Delta IV to build the 5 meter Atlas. ULA would probably want to upgrade from the two-nozzle RD-180 to the four-nozzle RD-171 as used in the Zenit rocket (nearly double the thrust, and would solve NASA's fears about upping the first-stage thrust to depress the trajectory.) The new rocket could use the 5-meter upper stage used on the Delta IV Heavy, if the twin-engine layout from the Atlas V was added. In that sense, the new rocket would appear to be a "Delta-Atlas" hybrid.
The consequences of "Delta-Atlas" could be far reaching. As a reliable, single-core booster that can launch a ten-man spacecraft like the HL-20, it could open the frontiers of orbital space tourism. The triple-core version of "Delta-Atlas" could launch hotels for space tourists, resupply a moon base, and even launch elements of a Mars-bound spacecraft.
In short, "Delta-Atlas" has commercial viability in the short term (thanks to the single-core version,) even before a moon base is established to make a heavy-lifter economically viable. I'd like to see The Stick and the shuttle-derived heavy lifter (and the associated army of support personnel) pull that off.
With the current EELV's currently unprofitable, why should we build a bigger one? There are actually a few good reasons for doing so. For starters, manned spacecraft in the HL-20 class will weigh approximately 25 tonnes once the launch abort system is factored in. While this is within the capabilities of the current EELV-Heavy rockets, the need for parallel stages increases the risk of first stage engine failure. If a single-core rocket could boost the HL-20, it would be much safer for a human crew.
There are other benefits to a bigger EELV that can launch 25-28 tonnes in its single-core variant. The single-core booster could launch Geosynchronous-orbiting satellites and the Pentagon's polar-orbit satellites, both of which have similar energy requirements to the HL-20.
NASA's previous studies have poo-pooed the EELV's for launching manned spacecraft. They point to "highly lofted trajectories" on the upper stages that would produce heavy deceleration loads in the event of an abort. NASA also feels that the current ISS requirements for the CEV can't be met by the current Delta or Atlas. Finally, NASA strikes down the EELV's under the ill-defined hammer of "human-rating."
In response to NASA, they have a legitimate point regarding the abort loads, but they preface those comments with "single engine upper stage." Has the analysis been done for the dual-engine Centaur that is part of the Atlas V family? Also, the ISS requirement for the CEV is only a problem because NASA insists on flying the CEV to the ISS using the same service module as used on the moon missions. The CEV could get away with a much smaller service module for these missions; as Mark Wade points out, the CEV is carrying an extra 9.3 tons of propellant that will likely go to waste.
Shooting down the "human rating" requirement is as easy as shooting fish in a barrel. After all, NASA had no problem human-rating the Redstone, Atlas D, or Titan II, even though all of those missiles had been designed for hurling warheads at the commies. Obviously there will need to be trajectory modifications to limit the g-forces, and some form of vehicle performance-monitoring to activate the escape system if a failure is detected. None of these are show-stoppers, and they are much cheaper than building The Stick from scratch. Of course, the Shuttle was never really "human-rated" either. Let me refer you to the shuttle abort procedure, as taken from the shuttle pilot's manual.
1.) Place head between legs.
2.) Kiss butt goodbye.
In short, any EELV can be made safer than the shuttle. The Stick is not necessary.
My optimal solution to the issue of CEV launch is a 5-meter diameter variant of the Atlas V. This was actually addressed in the ESAS report as "Atlas Phase 2, 5.4 meter." It would (hopefully) combine the reliability, modularity, and lean pad processing of the Atlas V with the lifting abilities sought in The Stick. Furthermore, three Atlas (5-meter) cores could be strapped together to form an unmanned heavy lifter. While this rocket would have about half the capability of the shuttle-derived heavy lifter, it would be a lot cheaper to build a 5-meter Atlas than it would be to build both The Stick and the shuttle-derived heavy lifter.
The 5-Meter Atlas could be the best thing to come out of the merger of Atlas and Delta production lines. United Launch Alliance can start out with the 5 meter tooling for the Delta IV to build the 5 meter Atlas. ULA would probably want to upgrade from the two-nozzle RD-180 to the four-nozzle RD-171 as used in the Zenit rocket (nearly double the thrust, and would solve NASA's fears about upping the first-stage thrust to depress the trajectory.) The new rocket could use the 5-meter upper stage used on the Delta IV Heavy, if the twin-engine layout from the Atlas V was added. In that sense, the new rocket would appear to be a "Delta-Atlas" hybrid.
The consequences of "Delta-Atlas" could be far reaching. As a reliable, single-core booster that can launch a ten-man spacecraft like the HL-20, it could open the frontiers of orbital space tourism. The triple-core version of "Delta-Atlas" could launch hotels for space tourists, resupply a moon base, and even launch elements of a Mars-bound spacecraft.
In short, "Delta-Atlas" has commercial viability in the short term (thanks to the single-core version,) even before a moon base is established to make a heavy-lifter economically viable. I'd like to see The Stick and the shuttle-derived heavy lifter (and the associated army of support personnel) pull that off.
posted by Mr. X at
9:57 AM
