|Artist's concept of a manned expedition to an asteroid. Photo Credit: NASA
In what NASA Administrator Charles Bolden called “one of the most important decisions to be made this decade” NASA has announced that it intends to build a new “heavy lift” launcher that is more powerful than the legendary Saturn V. Known as the Space Launch System, this new monster rocket is intended to restore America’s deep space capabilities and take US astronauts beyond Earth orbit to the asteroids and one day all the way to Mars.
The project can trace its roots back to the Columbia disaster. Following the loss of a second Space Shuttle orbiter, the Columbia Accident Investigation Board (CAIB) concluded that it was in the country’s best interest to retire the Shuttle fleet as soon as the International Space Station was completed. President Bush agreed and ordered the Space Shuttle fleet retired. He replaced it with a new program intended to send astronauts back to the Moon and then to the planet Mars. The program was named Constellation.
Part of this program called for the creation of a new rocket called the Ares V “heavy
|Photo Credit: NASA
lift” booster. This booster was intended to restore the nations heavy lift capability which had been lost when the Saturn V was retired back in the 1970s.
The Ares V was a giant un-manned cargo booster constructed from a blend of Apollo, Space Shuttle, and Evolved Expendable Launch Vehicle (E.E.L.V.) technologies. The core would consist of an extended Space Shuttle External Fuel Tank. This would be powered by five RS-68 engines from the Delta IV E.E.L.V. program.
Flanking the tank would be twin evolved five segment Space Shuttle Solid Rocket Boosters (S.R.B.) This type of S.R.B. would have considerably more lift the four segment S.R.B.s used to launch the Space Shuttle. The vehicle would have an upper stage powered by two evolved Apollo J-2 engines known as the J2-X.
The Ares V would be able to propel up to 130 metric tons into low Earth orbit. The second stage could also function as an Earth Departure Stage that could send up to 60 metric tons to the Moon.
All of this sounded great on paper except for one thing. Nobody ever funded it. President Bush’s idea was that NASA could do much of the preliminary work before the Shuttle retires and then once the Shuttle is gone use its budget to fund the construction of Constellation.
The problem with this approach was that it allowed for no overlap and as a result left NASA without a booster or a spacecraft while the Constellation vehicles were being built. This was not a problem in the 1970s when NASA was left without a booster and spacecraft while the Space Shuttle was being developed. Back then the Spacecraft was the space program. But today NASA has a space station to think about and without a booster and spacecraft American astronauts were grounded. The centerpiece of America’s space program would have no American’s!
The Bush administration solved this problem by cutting a deal with the Russians allowing NASA to purchase rides to the International Space Station on their Soyuz spacecraft. This left NASA completely dependent on its former cold war rival for access to its manned assets in space.
When the Obama administration took office in 2008 the President ordered a complete review of the Constellation program. The review found the program to be mired in cost overruns and delays. What had started as a 5 year period with no US manned spacecraft had now grown to a 7 year period with further delays almost guaranteed. The Ares V heavy lift would not even begin development until 2015 at the earliest!
|SpaceX's Falcon 9 booster and Dragon spacecraft. The company hopes to be flying crews to ISS within three years. Photo Credit: SpaceX
By this time a new movement had begun taking hold within the American space program – privatization. Private industry had been developing boosters for decades and several companies were already constructing their own manned spacecraft. These companies were lobbying hard for NASA to use their boosters and spacecraft thereby saving the taxpayers the cost of developing these vehicles while landing lucrative contracts for themselves.
The President, looking for a way to spur innovation and create jobs, decided it was time for a radical change at NASA and he canceled the Ares V along with the rest of the Constellation program. He then ordered NASA to work with commercial firms to develop private spacecraft. Under this program NASA would no longer own its own spacecraft. Instead it would buy rides on vehicles owned, developed, and operated, by several competing corporations.
Almost at once the space community erupted in controversy about the wisdom of this new direction. Most angry of all were members of the U.S. Congress and Senate who were not consulted in advance. Their major concern was that these companies had no experience building manned spacecraft and that the nation, already in the precarious position of being dependent on foreign governments for manned access to space, could not afford to take the risk.
Everything boiled over in 2010. By now there was a strong sentiment that NASA had been gutted. A joint communication issued by Apollo astronauts Neil Armstrong, James Lovell, and Eugene Cernan echoed this sentiment:
"For the United States, the leading space faring nation for nearly half a century, to be without carriage to low Earth orbit and with no human exploration capability to go beyond Earth orbit for an indeterminate time into the future, destines our nation to become one of second or even third rate stature."
These words were heard loud and clear. A bi-partisan group of Senators led by Bill Nelson (D) Fla. and Kay Bailey Hutchison (R) Texas fired back at the President’s plan with section 309 of the NASA Authorization Act of 2010. There they wrote into law orders for NASA to develop a heavy lift “Space Launch System” and Multi-Purpose Crew Vehicle (MPCV) thereby guaranteeing that NASA would have some sort of booster and spacecraft in place as insurance against setbacks in the commercial spaceflight program.
But it didn’t stop there. By specifically calling for a “heavy lift” Space Launch System, the act would insure that NASA restored its deep space capabilities. This would pave the way for efforts to explore beyond Earth orbit and out the solar system.
The act was signed into law by President Obama as part of a budget compromise and NASA’s heavy lift booster was re-born.
The act outlined three minimum requirements for the new booster:
- The Vehicle must be able to initially lift 70-100 tons to low Earth orbit but it must be evolvable to eventually lift 130 tons or more.
- The vehicle must be able to lift a MPCV
- The vehicle must be capable of serving as a back-up system for supplying and supporting cargo and crew delivery requirements for the International space station in the event such requirements are not met by available commercial or partner supplied vehicles.
Guidance from NASA Administrator Charles Bolden refined this order stating that the system must also meet three additional criteria: it must be affordable, sustainable, and realistic.
On December 6, 2010 NASA formally established a planning team at the Marshall Spaceflight Center for the new booster. Over the course of the last decade NASA had analyzed more than 2,000 separate launch vehicle proposals. Of these the team created a short list of five proposals. These were:
- A booster who’s core is 27.5 feet in diameter and powered by five RS-25D/E engines (Space Shuttle Main Engines). The upper stage would be powered by a single J-2X engine. This booster would be augmented by two five segment Space Shuttle solid rocket boosters.
- A booster who’s core is 33 feet in diameter and powered by six RS-68 engines. The upper stage would be powered by two J-2X engines. This booster would also be augmented by two five segment Space Shuttle solid rocket boosters.
- A booster who’s core is 33 feet in diameter and powered by five 2.0 MLBF RP (lox and kerosene) engines. The second stage would be powered by a single J-2X engine.
- A booster with a 33 foot diameter core powered by five 51.25 MLBF thrust RP engines with an upper stage powered by a single J-2X engine.
A quick look at these first four proposals shows that there are two schools of thought
|The new RP hydrocarbon engine will be a lot like these F-1 engines used to send astronauts to the Moon. Photo Credit: Rocketdyne
here. The first two proposals are both very similar to the Ares V heavy lift booster with a liquid hydrogen/liquid oxygen core augmented by evolved solid rocket boosters and a J-2X second stage. The last two were very different.
Back in May of 2010 NASA initiated a joint study with the Department of Defense to look into the feasibility of developing a large hydrocarbon based engine that could be used by both NASA and the Department of Defense. These engines are also known as Rocket Propellant engines or just RP engines.
RP engines run on liquid oxygen and kerosene (called RP-1) just like the Apollo Saturn V did and the Atlas V E.E.L.V. still does. These RP “hydrocarbon” engines could produce between 1 and 1.25 million pounds of thrust each and would be very similar to the F-1 engine that powered the Saturn V Moon rockets.
So the final proposal was a hybrid:
- A core module powered by liquid hydrogen and liquid oxygen augmented by liquid rocket boosters powered by a hydrocarbon based RP engine combination with a J-2X second stage.
In selecting one of these proposals NASA had to take several factors into account. The basic scoring system worked like this:
- Affordability: 55%
- Schedule: 25
- Performance: 10
- Programmatic: 10%
There were significant benefits to choosing the all liquid hybrid configuration. First
|The J2-X second stage engine. Photo Credit: NASA
off it would give the United States a large all liquid engine that could be used in a variety of boosters - including commercial boosters. Additionally, the all liquid configuration would be significantly safer than any configuration that used solids. Liquid engines can be throttled up or down and even turned off in an emergency. A solid booster can-not.
The big problem with the liquid engines was time. It would take years for the DOD and NASA to develop the new engine and the law mandated that NASA should be ready to fly the new booster by 2017.
There were also significant benefits to the solid rocket approach.
|Five segment SRB test. Photo Credit: ATK
NASA possessed significant assets left over from the Constellation program. Among these assets were the five segment solid rocket boosters that were already under development for the Ares V, the J-2X engines that were being developed for the Ares second stage, and a launch escape system that had already been developed and tested for the Orion crew capsule. Additionally NASA had significant Space Shuttle assets including Launch Complex 39, the VAB, the Launch Control Center, and the Crawler Transporters.
But of all these assets the greatest was NASA’s existing workforce. These people were all looking at lay-offs due to the shift to commercial boosters and the end of the Space Shuttle Program. Combined they represented a 30 year investment in an extremely skilled labor force.
How could NASA simply through all of this away?
With affordability and schedule accounting for 80% of the design criteria, and the space authorization act already ordering NASA to take advantage of existing contracts in developing the S.L.S, it quickly became clear that the “all liquid” option was not going to work. But the new hydrocarbon engines also represented a technology too promising to reject outright. So NASA chose both.
|Manned version of the Space Launch System. Photo Credit: NASA
In order to “jump start” the program NASA decided to leverage as much existing technology as possible. The S.L.S. will use five Space Shuttle Main Engines to power its core stage which itself will be an elongated Space Shuttle External Fuel Tank. The five segment Solid Rocket Boosters, currently being developed for the now defunct Ares V, will be utilized to augment the core. The booster’s upper stage will be powered by a single J2-X engine which was also already under development for the Ares V.
In addition to speeding things along, making use of this “heritage” technology will enable the S.L.S. to make use of existing facilities at NASA’s Kennedy Space Center reducing the need for new ground support equipment. Most importantly, NASA can utilize its current workforce who are already intimately familiar with Space Shuttle hardware and ground processing equipment.
This will be the man rated version of the booster. Standing 365 feet tall it will be able to launch up to 70 metric tons into space. This is about 10% more than a Saturn V could and about three times that of a Space Shuttle. But it doesn’t stop there. The space act also called on NASA to develop an evolvable system that could ultimately place at least 130 metric tons into space.
There are currently 25 Space Shuttle Main Engines in NASA’s inventory. Once these
| Space Launch Ststem evolved payloader. Photo Credit: NASA
are flown out NASA does not plan to build more. Instead, they plan to hold a design competition for new, more powerful, engines and boosters. This answers long standing pressure to bring industrial competition into the mix.
It is believed that by this time the RP engines could be well developed and available for use on the boosters. This would create an all liquid hybrid system that could put up to 130 metric tons into space. Including its 10 meter payload fairing, this cargo configuration of the booster will stand 400 feet tall – 40 feet taller than the Saturn V ! It will also be able to lift 20% more weight.
NASA intends to begin un-manned test flights of the Space Launch System with a test vehicle in 2017. The test vehicle will sport only three Space Shuttle Main Engines and will make use of a Delta IV upper stage. Flights with a J2-X powered second stage and a full complement of engines should follow at the rate of about one per year. All of this will culminate with the first crewed flights beginning around 2021.
If this schedule holds the S.L.S. could be used to put astronauts on an asteroid as early as 2025.
This may seem like a long time to get things back on track but as Bill Gerstenmaier, associate administrator for Human Exploration and Operations, put it "Yes, it takes a long time, but when we're finished we'll be capable of going to space like no other nation
Administrator Bolden summed it all up saying “President Obama challenged us to be bold and dream big, and that’s exactly what we are doing at NASA. While I was proud to fly on the Space Shuttle, kids today can now dream of one day walking on Mars.”
Contact the author: Robert@interspacenews.com