WASHINGTON--Dogged by rumors that AresI rocket would not be able to lift the OrionCrew Exploration Vehicle if the booster was built as currently envisioned,NASA's Constellation program manager has shot back at unnamed critics in ane-mail missive he said he wrote to set the record straight.
"[M]any whocarp from the sidelines do not seem to understand the systems engineeringprocess. They instead want to sensationalize any issue to whatever end orpreferred outcome they wish," wrote Jeff Hanley the NASA official leading thedevelopment of the rockets and spacecraft the United States is building toreplace the space shuttle andto return to the Moon.
In the Nov.13 e-mail, which circulated beyond NASA just within hours after he hit the send button, Hanley said he was writing in partto respond to a posting that had appeared over the weekend on the widely-read website NASA Watch declaring"Big Problems with the Stick."
NASAWatch's short Nov.11 posting said the Ares I, also known as the Stick, "is underpowered to the tuneof a metric ton or more" and would not be able to lift Orion. Theinformation was attributed to reports from "sources inside the development ofthe Ares I launchvehicle."
What NASAWatch was reporting was the latest twist on what the aerospace communityhas been whispering about for months--that the space shuttle-derived design NASApicked for Ares I and its heavy-lift follow-on, the Ares V, is rife withproblems and the agency would be better off taking some other approach.
That theaerospace community was buzzing with talk of Ares problems was not lost onHanley and other senior NASA officials. Steve Cook, NASA's Ares programmanager, was dispatched to speak at a Space Transportation Associationbreakfast here in October in an attempt to get ahead of the rumor mills,officials familiar with the behind-the-scenes preparations said.
Hanley saidin an interview he normally does not respond sodirectly to what he characterized as misinformation that appears in "the pseudo media--blogs and soforth."
But the NASAWatch post spurred him to action. Hanley sent his e-mail, he said, to"a few dozen Constellation leaders throughout the program"--a long enoughdistribution list, it would seem, to ensure the message leaked to an even wideraudience.
"I thoughtit was important that we set the record straight on some of the external stuffthat's been going around. I don't want people to think that because they don'tsee us responding to it on a regular basis that has any basis in truth," saidHanley, who spoke to Space News in a Nov. 15 telephone interview fromJohnson Space Center in Houston, where the agency's first systems requirementreview for Orion and the Ares rocket had wrapped up the day before.
Hanley wasjoined on the interview by Cook and Scott Horowitz, NASA's associateadministrator for exploration systems.
Hanley saidthe review, which was attended by NASA Administrator Mike Griffin and theagency's chief engineer, Chris Scolese, found that Ares I remains on track tolift the Orion spacecraft with performance to spare.
Reiteratingpoints made in his e-mail, Hanley said the latest analysis shows that Ares Ican lift (58,000 pounds) 26,100 kilograms to its low Earth orbit drop-offpoint. Its sole intended payload, Orion, is still running 15-20 percent belowits NASA-imposed 48,500-pound (21,825-kilogram) weight limit fully fueled, he said.
The Ares Imain stage is a larger five-segmented version of a space shuttle solid rocketbooster. The rocket would be topped with a liquid-oxygen- and hydrogen-fueledupper stage powered by an updated version of the J-2 engine that flew on theSaturn 5.
NASAoriginally intended to use the shuttle's smaller four-segment booster for the AresI main stage and use a more powerful shuttle main engine for the upper stage,but decided in January to go with a five-segment main stage and a J-2X for theupper stage in order to achieve greater commonality with the Ares V, theheavy-lift rocket NASA intends to start developing around the end of the decadefor Moon missions.
The Ares V, as envisioned, will usea pair of five-segment solid rocket boosters to help lift a cryogenic mainstage powered by a cluster of the RS-68 engines now used on the Delta 4 rocket.The J-2X would come back in play as the main engine for the Ares V's EarthDeparture Stage.
Cook, who runs the Ares program fromMarshall Space Flight Center in Huntsville, Ala., said the mass and performanceof Ares I and its Orion payload do get a lot of attention from theprogram, but he said claims that Ares I is underpowered are simply not true.
"Mass and performance are things youare going to always have to track on any aerospace vehicle, especially one thatwants to go to orbit," Cook said. "You've got to treat it seriously and youhave got to keep up with it as you go along. But we can lift what we need tolift with 15 percent performance margin."
Cook said AresI weight and performance projections have fluctuated in the 10 months sinceNASA switched to the five-segment/J-2X combo, but said that is typical for anyaerospace vehicle making the transition from detailed concept to preliminarydesign.
"We've started building the vehiclefrom the bottom up," Cook said. "And the first time you do that, youfind that everybody starts putting margin in the system and it comes outweighing more and getting less performance than you initially projected," hesaid. "Then you start working back down, 'why is it that way?' and you work itback down through the process. This is standard 101 stuff that goes on. It'sfluctuated up and down. It's part of the normal design cycle."
Citing an example, Cook said the AresI weight estimates shot up earlier this year when the program looked for waysto reduce manufacturing costs on the upper stage by penciling in "all kinds ofcommonality", such wall thickness and common domes.
"Well, itturned out it wasn't going to work so we had to back off and be less aggressivein how did the design and do it more like we had done upper stages in thepast," he said.
Cook saidthe Ares I upper stage is very similar to the Saturn-5's third stage in sizeand performance. "It held 240,000 pounds of liquid oxygen and liquid hydrogen.We hold [280,000 pounds]. It had one J-2 engine. We have one J-2X engine. So weare a little bit bigger and a little bit higher thrust, but we are in that samethrust category," he said. "That gives us confidence that what we are shootingfor will work."
The preliminary design review for AresI is in February 2008, about 14 months away. The critical design review, whenNASA nails down the design and starts producing the vehicle, is slated for late2009.
Orion'spreliminary and critical design reviews are slated for summer 2008 and summer2009, respectively.
Hanley saidDenver-based Lockheed Martin Space Systems, selected in late August as theOrion prime contractor, has spent the last two months incorporating a few NASAchanges into its winning spacecraft design.
A revisedreference design for Orion, Hanley said, is not due until early December.Still, he said, all indications are that Orion is staying well within its masstargets.
"If youheld their feet to the fire and asked them what is their no-kidding projectedmass, it would be something on the order of 15-20 percent lower than 48,500pounds (21,825 kilograms)," he said. "They have plenty of margin."
Hanley saidweight will remain at the top of his watch list until Orion and Ares actuallylaunch. Weight estimates will fluctuate, he said, as engineers work the trades offs that go along with designing aspacecraft or rocket.
"Six monthsfrom now, the Orion guys could come in and say, 'hey, we are 1,000 pounds (450kilograms) over.' Okay, so back to work. Go solve it," Hanley said. "That's theway the game is played."
Ares gossipheard from industry sources is often accompanied by subtle, and sometimes not so subtle, advocacy for alternative approaches,such as using the Atlas 5 or Delta 4 Evolved Expendable Launch Vehicles as thebasis of NASA's new transportation system.
Cook saidthat is to be expected given the stakes.
"Part ofthis is because we haven't done a design of an exploration-class system,whether it's the crew vehicle or the launch vehicle, in 40 years ... so when ithappens, everybody is clamoring to get a piece of it and want to help" Cooksaid. "And I don't think it helps, frankly, that over the last 15 years NASAhas been a little inconsistent in what it wants to do. But when the presidentput out the vision in 2004 we got a very clear message of how to go be focused.And that was the first focusing event in well over a decade."
Horowitzdismissed anonymous claims of trouble on Ares as "rumblings from people whodidn't get their particular favorite rocket design picked."
Horowitzhas championed the single stick design for Ares I since shortly after the 2003Space Shuttle Columbia accident claimed the lives of seven of his fellowastronauts. He continued his advocacy for what some called "the Scotty rocket"during a brief stint at ATK Thiokol, the Promontory, Utah-based solid-rocketbooster firm picked to build the Ares I main stage.
Horowitzsaid NASA looked at 10,000 to 20,000 iterations of different designs as part ofan intensive Exploration Systems Architecture Study before selecting the crewand cargo launcher concepts the agency unveiled in September 2005.
"Are thereother solutions that would work? Sure," Horowitz said. "But so does this one.This is ours. And this is where we are going. And occasionally you're justgoing to get noise in the system. We try to educate people. It's just noise."