Numerous news articles recently have reported problems with the Ares rocket. Some articles detailed critical design flaws, others wondered if Ares was doomed, others reported that Ares was on the US Congress’s “chopping block,” and still others purported that a different launch architecture would be superior to the Ares design. So many rumors were floating around that NASA felt the need to hold a press briefing yesterday to address the rumors and calm any fears that the Constellation program was on the verge of collapse. At the briefing, NASA officials said that while there are some challenges for the program to overcome, Ares is making outstanding progress toward flight. “Some recent news reports about Ares have been inaccurate and draw false conclusions,” said Steve Cook, who leads the development of the rocket.
But isn’t that what everyone expected them to say? Are they telling the truth? To get an unbiased look at the state of the Constellation program, Universe Today contacted Dr. Scott Pace, who is the Director for the Space Policy Institute at George Washington University in Washington, DC. Pace said the problems facing Ares are typical and not insurmountable, and that Constellation is the right choice for our country’s space program. “In my view,” said Dr. Pace, “if the nation is going to return to the Moon and eventually send humans to Mars, then political and technical realities argue that the Ares I, Orion, and Ares V are the way to go.”
Pace said the only reason not to use the Constellation architecture is if our nation decides it is content with staying in low Earth orbit or decides to cease its participation in government sponsored human spaceflight.
Pace discussed some of the issues being debated for the Ares rocket. “From my perspectives, there are a couple of things going on that can be broken down into 1) normal technical issues, 2) system engineering issues, and 3) architecture issues,” said Pace.
He said the thrust oscillation issue is a typical issue with all solid propellant motors and there are multiple ways to solve it. “As an analogy,” said Pace, “the pogo issue with Saturn on its first flights was much more serious.”
As for the launch pad drift problems and cross-wind limits on launch, these issues, too, have multiple solutions. “The fast start up of solids compared to liquids means less time to ‘drift,’” said Pace. “However, if a solid goes bad, it goes real bad, and that’s why the abort motor system on the Orion has to be proven to work from the launch pad up to high altitude.”
Pace believes a potentially more serious issue that should be resolved by modeling and test flights are the bending moments of the SRB “stick” itself in flight. “It’s built out of segments, not a single structure and lacks the stiffing of attachment to an External Tank (as with Shuttle and the Ares V design). This is a classic systems engineering problem,” said Pace, and deferred that NASA engineers are more qualified to comment on that issue.
Other issues are criticisms over the architecture choice of Ares I and V, over using an EELV (Evolved Expendable Launch Vehicle) for Orion or the DIRECT 2.0 design of the “Jupiter” rockets.
“The EELVs don’t have the performance to launch a 6-person Orion to ISS or take a 4-man crew to the Moon,” said Pace. “If one built a 3-4 person Orion to go only to ISS, it begs the question of what to do with the other ISS crew in an emergency and creates a potential government competitor for COTS providers.”
Pace said the use of EELV’s also means trying to creating a separate vehicle to provide lift to go to the Moon and Mars. “One could do the Moon with multiple EELV launches (as the Chinese might do with their Long March 5) at additional cost and risk over an Ares I and Ares V launch combination,” said Pace. “But you’re not going to Mars without a heavy-lifter like Ares V.”
Pace continued, “So, if we truly would like to go to Mars, build an Ares V and use it to make going to the Moon efficient. If we’re using an Ares V, separating humans onto a Ares I that shares much of the industrial base with the current Shuttle makes sense. This also allows an Orion capsule that can meet ISS and lunar requirements.”
Pace said EELVs could be useful for cargo to the ISS and, if someone were to pay for man-rating, they may even be useful for COTS crew missions. “But they can’t do the baseline government job of assuring U.S. human access to space.”
To make the Constellation program a success, Pace said NASA will need to focus on configuration control and consistency of analytical models, making sure the avionics interfaces are sufficient and being able to obtain adequate funding of full-scale tests.
* Author’s note: As an addendum, Dr. Pace said he has no problem with adding that he recently worked for NASA’s Program Analysis & Evaluation office, a fact I did not include in the article. “I understand that some may see that as a bias and perhaps relevant,” he said. Dr. Pace was named the Director of SPI in May 2008.