DIRECTly Seeing the Light
It appears that Mark Whittington is warming to the DIRECT approach for shuttle-derived heavy lift. I take this as a sign that the current ESAS plan, with all of the major revisions that have been made between Fall 2005 and now, is losing support amongst space enthusiasts and amongst technically-inclined observers outside the halls of NASA.
I've always been conflicted between DIRECT and an EELV-based approach to space exploration, from a technical standpoint. I like the free-market approach taken with launching crew on a wide-bodied Atlas, and launching cargo on a cluster of wide-bodied Atlas cores. But DIRECT lives up to its name in terms of being quick to develop and test, and it's markedly efficient at the politically-driven goal of preserving the (inefficient) shuttle infrastructure and jobs.
In a recent post, I discussed the weight issues associated with Ares V (probably to be renamed Ares VI if the extra RS-68 engine is slipped in.) The rocket is growing to address performance shortfalls, but it has become too heavy for the existing crawlers, too heavy for the existing launch pad, and too heavy for the hard stand on which the mobile launcher sits. I suggested that NASA should have initially determined weight and size limits on their rocket, based on the existing infrastructure, and limited the weight and size of Ares V to fit within those requirements. If that rocket were insufficient to meet the lift requirements for Project Constellation, use two heavy-lifters instead of one heavy-lifter and one crew launcher.
In that case, the resulting heavy-lift rocket would probably look a lot like the Jupiter-232. But in the current political climate, it will probably not happen for a variety of reasons. For one, Mike Griffin's NASA didn't invent it. Will NASA be able to swallow its pride and accept an outsider proposal? Probably not, at least not under the current leadership. Secondly, DIRECT is a modern update of the Martin "New Launch System" proposal, done by a small group of industry outsiders and assisted by NASA employees working off-the-clock. If there is to be any honest, technical discussion about the merits of DIRECT versus ESAS, the NASA "traitors" who assisted the DIRECT team will need immunity. Finally, DIRECT doesn't rely on five-segment SRB's, which will deny billions of R&D dollars to ATK.
At the same time, it's clear that "A Change is Gonna Come," to quote Sam Cooke. The current architecture is not viable politically, fiscally, or technically. Mike Griffin, by his own admission, is done when the Bush Administration leaves office. The next president, regardless of party, will be under tremendous political pressure to save shuttle jobs. It would not be a stretch for the incoming NASA administrator to order a 60- or 90-day study of existing launch plans. At the end of the study, the new administrator would announce that NASA has "refined" its launch vehicle concept, whether it be Ares II/III (renamed Jupiter 120/232) or Shuttle-C for cargo plus EELV's for crew launch.
DIRECT is admittedly not the perfect solution to the problems of shuttle-derived heavy lift. Modifications will still be required at the launchpad and on the shuttle's fixed service structure, although none of them will be as drastic as what's currently in store for Ares V. The upper stage of Jupiter-232 is a question mark. Conceptually, it's a bigger version of the Centaur from Atlas V, with two J-2X engines in place of the RL-10A-4's. It remains to be seen how well the Centaur "balloon tank" concept will scale up (although the Jupiter upper stage will not be a purely pressure-stabilized design.) The problem once on-orbit is that the two J-2X's of the Jupiter upper stage have too much thrust to push the Orion-Altair stack without breaking the docking mechanism. There are many ways around this problem, such as throttling down the engines, or having Orion and Altair delay their docking until both have arrived in lunar orbit.
It's impossible to say what's going to become of ESAS, between the reported technical problems and the ever-shifting whims of Washington. But it's safe to say that if NASA can swallow its pride, the DIRECT guys have offered them an easy way out.
I've always been conflicted between DIRECT and an EELV-based approach to space exploration, from a technical standpoint. I like the free-market approach taken with launching crew on a wide-bodied Atlas, and launching cargo on a cluster of wide-bodied Atlas cores. But DIRECT lives up to its name in terms of being quick to develop and test, and it's markedly efficient at the politically-driven goal of preserving the (inefficient) shuttle infrastructure and jobs.
In a recent post, I discussed the weight issues associated with Ares V (probably to be renamed Ares VI if the extra RS-68 engine is slipped in.) The rocket is growing to address performance shortfalls, but it has become too heavy for the existing crawlers, too heavy for the existing launch pad, and too heavy for the hard stand on which the mobile launcher sits. I suggested that NASA should have initially determined weight and size limits on their rocket, based on the existing infrastructure, and limited the weight and size of Ares V to fit within those requirements. If that rocket were insufficient to meet the lift requirements for Project Constellation, use two heavy-lifters instead of one heavy-lifter and one crew launcher.
In that case, the resulting heavy-lift rocket would probably look a lot like the Jupiter-232. But in the current political climate, it will probably not happen for a variety of reasons. For one, Mike Griffin's NASA didn't invent it. Will NASA be able to swallow its pride and accept an outsider proposal? Probably not, at least not under the current leadership. Secondly, DIRECT is a modern update of the Martin "New Launch System" proposal, done by a small group of industry outsiders and assisted by NASA employees working off-the-clock. If there is to be any honest, technical discussion about the merits of DIRECT versus ESAS, the NASA "traitors" who assisted the DIRECT team will need immunity. Finally, DIRECT doesn't rely on five-segment SRB's, which will deny billions of R&D dollars to ATK.
At the same time, it's clear that "A Change is Gonna Come," to quote Sam Cooke. The current architecture is not viable politically, fiscally, or technically. Mike Griffin, by his own admission, is done when the Bush Administration leaves office. The next president, regardless of party, will be under tremendous political pressure to save shuttle jobs. It would not be a stretch for the incoming NASA administrator to order a 60- or 90-day study of existing launch plans. At the end of the study, the new administrator would announce that NASA has "refined" its launch vehicle concept, whether it be Ares II/III (renamed Jupiter 120/232) or Shuttle-C for cargo plus EELV's for crew launch.
DIRECT is admittedly not the perfect solution to the problems of shuttle-derived heavy lift. Modifications will still be required at the launchpad and on the shuttle's fixed service structure, although none of them will be as drastic as what's currently in store for Ares V. The upper stage of Jupiter-232 is a question mark. Conceptually, it's a bigger version of the Centaur from Atlas V, with two J-2X engines in place of the RL-10A-4's. It remains to be seen how well the Centaur "balloon tank" concept will scale up (although the Jupiter upper stage will not be a purely pressure-stabilized design.) The problem once on-orbit is that the two J-2X's of the Jupiter upper stage have too much thrust to push the Orion-Altair stack without breaking the docking mechanism. There are many ways around this problem, such as throttling down the engines, or having Orion and Altair delay their docking until both have arrived in lunar orbit.
It's impossible to say what's going to become of ESAS, between the reported technical problems and the ever-shifting whims of Washington. But it's safe to say that if NASA can swallow its pride, the DIRECT guys have offered them an easy way out.
Labels: Launch vehicles, manned spacecraft, NASA, TeamVision, Vision For Space Exploration
posted by Mr. X at
12:00 PM
