Deriving Economically Sustainable Crew Launch Vehicles from the SLS

by Marcel F. Williams

With the end of the Space Shuttle era, there has been much focus on the emerging commercial crew industry in America with the hope that these vehicles will be ready to transport humans into orbit by the middle of the decade. However, by law, NASA's new SLS (Space Launch System) must also be capable of launching humans into orbit and beyond while also serving as a backup system for delivering crew and cargo to the ISS if such missions cannot be met by the private commercial crew companies.

It has generally been assumed that the crew launch vehicle derived from a shuttle space launch system (SLS) will simply be composed of an inline LOX/LH2 rocket coupled with two 4-segment or 5-segment solid rocket boosters (SRBs). Such a system would be capable of carrying a 20 tonne Orion-MPCV (Multi-Purpose Crew Vehicle) to LEO plus perhaps an additional 40 to 50 tonnes of payload to orbit.

However, without an upper stage (US), such a crew launch vehicle would have very limited beyond LEO capabilities.

But with an upper stage, a crewed SLS should be capable of transporting the 20 tonne Orion plus an additional 10 to 20 tonnes of payload practically anywhere within cis-lunar space (the Lagrange points: L1, L2, L4, and L5 and lunar orbit). And as an unmanned vehicle, the SLS could eventually evolve into a system that could carry as much as 200 tonnes to LEO and 80 tonnes to L1 if it utilized up to four 5-segment SRBs plus and upper stage.

Right: crew launch vehicle with two 4-segment SRBs capable of transporting the Orion-MPCV to LEO ; left: crew launch vehicle with two 4-segment SRBs plus and upper stage (US) capable of transporting the Orion-MPCV anywhere within cis-lunar space

However, as a crew launch system could be much simpler, safer, and cheaper to operate if the SLS was launched without the SRBs. The only fatal crew launch accident ever to occur during the Space Shuttle era was due to a malfunction in the SRBs O-ring that allowed how gases and plumes to critically damage the adjacent cryogenically fueled external tank; the subsequent explosion destroyed the vessel and killed the crew. So in a new launch system, crew safety has to be a priority.

Shuttle derived LOX/LH2 core vehicle capable of launching a 20 tonne Orion-MPCV with a stretched SM with 8 to 9 tonnes of extra hypergolic fuel to LEO

A stretched shuttle derived LOX/LH2 without SRBs could send the Orion capsule to LEO by simply using the hypergolic fueled Service Module (SM) as an upper stage. An additional 8 to 9 tonnes of hypergolic fuel in a stretched SM with could transport 20 tonnes to LEO. Boeing Inc. has already conceived such a SLS derived crew launch vehicle without the SRBs.

Left: Cis-lunar crew launch vehicle, center: HLV cargo vehicle using two 4-segment SRBs, right: HLV cargo vehicle using three LOX/LH2 core vehicles

However, a stretched shuttle derived core vehicle with a large upper stage-- but still without SRBs-- could transport the 20 tonne Orion MPCV anywhere within cis-lunar space. If the upper stage is equipped with multiple RL-10 engines then the crew launch vehicle would have uber-safe engine-out capability in both first and second stages. This would allow NASA conduct simpler and safer manned cis-lunar missions to L1, L2, L4, L5, and lunar orbit almost immediately after the SLS becomes operational in 2016. And NASA is required by law to define near term manned missions for the SLS within cis-lunar space.

Orion-MPCV on cis-lunar mission to lunar orbit

Coupled with SRBs, the SLS would be the only vehicle capable of deploying the largest 65 tonne plus Bigelow space stations (BA-2100) to LEO or sending the smaller 25 tonne water shielded Bigelow space stations (BA 330) to the Lagrange points. While such Lagrange point space stations would still have too little shielding to provide astronauts with adequate protection against galactic radiation and especially potentially brain damaging heavy nuclei beyond a few weeks time, such stations would still contain enough water shielding to protect astronauts from the dangers of a major solar event.

As an orbital crew launch vehicle, the two stage LOX/LH2 vehicle might be capable of transporting the 20 tonne Orion plus 30 to 40 tonnes of payload to LEO. While this might seem like overkill, it should be remembered that transporting humans to an orbital space station requires more than just transporting the human body. Every human requires nearly one tonne of water, oxygen, and food per month in order to survive in space.

Once Americans return to the Moon again (which should still be NASA's priority, IMO), it has been suggested that a reusable LOX/LH2 lunar lander be developed that utilizes fuel mined from the lunar poles. Such a lunar transportation system would be able to transport humans and cargo from the lunar surface to L1 and back. This would greatly simplify and reduce the cost of sending humans to and from the lunar surface. And such a simpler and safer SLS combined with a reusable lunar shuttle might be very attractive to private commercial spaceflight companies seeking to expand the emerging space tourism industry all the way to the lunar surface.

References

1. Heavy Lift Launch Vehicles with Existing Propulsion Systems

2. NASA’s Space Launch System - an All-Liquid Alternative

3. The NASA Authorization Act of 2010

4. Multi-Purpose Crew Vehicle

5. Orion Spacecraft

6. BA 330

7. Mission and Implementation of an Affordable Lunar Return

8. Conquering Cis-Lunar Space with Shuttle and ULA Derived Technologies

9. Boeing's New HLV Concept could be the DC-3 of Manned Rocket Boosters

Gary Lyles on NASA's Current HLV Concepts

Big Bigelow Space Station Concepts

BA 2100

Bigelow Aerospace Shows Off Bigger, Badder Space Real Estate

Conquering Cis-Lunar Space with Shuttle and ULA Derived Technologies

by Marcel F. Williams

Congress has now made it clear that they want the immediate development of a heavy lift vehicle and a crew exploratory vehicle capable of beyond LEO missions and as a back up transport to the ISS. They have also made it clear that they want NASA to utilize technologies derived from both the Space Shuttle and Ares I/V programs since billions of tax payer money has already been invested in these technologies.

Some, however, have argued that utilizing a heavy lift vehicle as a crew transport to LEO violates the philosophy of improving safety by not combining crew transport with cargo transport. This was part of the driving philosophy of former NASA director, Griffin, when he decided to advocate the development of the Ares I as an ultra-safe crew transport vehicle and the Ares V as a mega-heavy lift cargo vehicle.

Recently, NASA has been promoting a philosophy of developing new transport systems that can be utilized not only by NASA but also potentially by the military space program and by private commercial space programs. The advantage of such a philosophy is that increased demand for common transport systems or components could reduce cost for everyone that utilizes such vehicles or components.

The deployment of space depots has been argued as another means for reducing the cost of space travel beyond LEO. And the development of reusable space craft that utilize in situ resources on the Moon or the asteroids has also been proposed as a way to reduce the cost of space travel.

But is there a way that NASA could cheaply incorporate all of these ideas? I believe the answer is yes!

The first step is to develop a simple shuttle derived core vehicle similar to that proposed by Boeing. The Boeing shuttle derived core vehicle could be utilized to transport humans into orbit without using solid rocket boosters (SRBs). But with SRBs, the Boeing core vehicle could be used as a heavy lift vehicle.

Boeing, however, advocates using four of the cheaper RS-68B engines for their crew launch vehicle concept while using the more fuel efficient RS-25E (disposable SSME) for the heavy lift vehicle. Man-rating the RS-68 rocket engines will probably increase the cost of these engines while making the RS-25 expendable will probably reduce their cost. Using the same engines in both the crew launch and the heavy lift vehicle will increase demand, further reducing production cost. So I advocate using the RS-25E in both the crew launch vehicle and the heavy lift vehicle.

Boeing also proposed using a stretched hypergolic fueled SM (Service Module), requiring an extra 8 to 9 metric tons of fuel in order for the crew launch vehicle to transport a 20 metric ton capsule and crew to LEO. The United Launch Alliance (ULA), however, has proposed using an ACES 41 as a LOX/LH2 fueled Service Module. Utilizing an ACES 41 SM with a shuttle derived crew launch booster which I'll call the SD-CV (shuttle derived core vehicle) could potentially lift more than 30 metric tons to LEO. Since the ULA plans to use the ACES 41 as a common upper stage for both the Atlas and the Delta IV, the high production demand for the ACES 41 by NASA and the ULA should help to reduce cost for the ACES 41.

SD-CV (Shuttle Derived Core Vehicle) and ULA's ACES 41 (credit ULA) concept used as a Service Module for an Orion capsule.

Boeing's heavy lift vehicle concept with an EDS could lift up to 120 metric tons to LEO while the crew vehicle could lift more than 30 metric tons to LEO (150 metric tons in combination). That's enough capacity to launch nearly 60 metric tons of payload to trans lunar injection or to the Earth-Lunar L1 Lagrange point.

The SD-HLV with an Altair lunar landing vehicle and the SD-CV with a Command Module (CM) and an ACES 41 Service Module (SM).

An SD-CV crew vehicle with the ability to launch over 30 metric tons into orbit would also give it approximately the same capabilities as the current space shuttle with the exception of not being able to return large payloads back to Earth. But the SD-CV should be substantially cheaper to operate than the shuttle since it does not require SRBs. The SD-CV could also be one of the safest manned launch vehicles ever developed since it would only have two stages, with each stage having multiple engines capable of supplementing a failed engine in both stages. Being hydrogen fueled would also make it potentially the greenest manned space vehicle ever developed. While a manned launched SD-HLV would still be safer than a space shuttle launch, the SD-CV should be equally as safe as a man rated Atlas V-401 and a substantially safer vehicle than an SD-HLV, Delta IV heavy, or a Falcon 9 (the two stage Falcon 9 only has one engine for the upper stage so a single engine failure in the upper stage would terminate the mission).

Any space capsule chosen by NASA for the Orion CEV (Crew Exploratory Vehicle) should be able to be used by NASA and private industry on top of an ACES 41 which could be used by an Atlas V or a Delta IV heavy. Again, the higher the demand for a particular crew capsule, the lower the capsule's production cost will be.

An SD-HLV lunar mission would launch an Altair into Earth orbit for a rendezvous with a CM-SM-ACES 41, or it could use the Altair to transport unmanned payloads (lunar base modules, vehicles, oxygen factories, etc.) weighing more than 10 metric tons to the lunar surface.

Because of its large payload capacity, some might question the private commercial viability of the SD-CV as a crew launcher against much smaller potentially manned rated launch vehicles like the Atlas 5 and the Falcon 9. However, if a payload carrier is placed between the command module and the service module, the shuttle derived crew carrier could also transport and additional 20 metric tons of cargo to LEO. While the space shuttle is banned from carrying commercial loads into orbit, a private commercial company would have no such restrictions!

SD-CV could be launched into to orbit for a rendezvous with the Altair for a lunar mission or it could be used to transports crew and cargo to the ISS or to private commercial space stations.

There are two principal options for the EDS (Earth Departure Stage) for the unmanned heavy lift vehicle: one that uses a single JX-2 engine and one that uses multiple RL 10 engines. Since the ACES 41 in this concept and the Altair lunar lander would also use RL-10 engines, using RL-10s in the EDS, Service Module, and Altair lunar lander would obviously increase the demand for the RL-10 which should reduce the production cost for the engine.

After the Orion-CM-SM-ACES 41 docks with the Altair and EDS (Earth Departure Stage), the EDS provides most of the delta-v for transferring the Altair and the Orion to the L1 Lagrange point.

The SM-ACES 41 provides the rest of the delta-v requirements for reaching L1 in addition to the delta-v for returning passengers to Earth. Limiting the Orion CM-SM-ACES 41 to L1 would substantially reduce the delta-v requirements for a lunar mission.

The single stage Altar vehicle would transport up to three metric tonnes of payload (crew transport module, cargo, and crew) from L1 to the lunar surface and back to L1. L1 departure for the Altair vehicle enhances the ability of the lunar lander to conveniently land at practically any point on the lunar surface.

The Altair lunar landing vehicle was originally proposed to have a LOX/LH2 descent stage and a hypergolic fueled ascent stage. However, there is no reason why a lunar landing vehicle can't be a single stage vehicle by simply using the descent stage to land and lift a small crew module weighing about 3 metric tons with four passengers and payload. This would mean that NASA would only have to develop one lunar vehicle instead of two, substantially reducing development cost. Plus the Altair descent stage would use an RL-10 engine which would further reduce the cost of the RL-10 engine used by both NASA and the ULA.

A single stage Altair vehicle with a crew transport module would be much cheaper to develop than the two stage Altair concept that uses both a LOX/LH2 descent stage and a hypergolic fueled ascent stage. For long term missions to a lunar base facility, a simple light weight aluminum sun shade could be used to cover and shield the vehicle from direct sunlight on the lunar surface in order to reduce hydrogen and oxygen fuel boil-off.

Any Moon base program that involves the production of oxygen and even hydrogen from lunar resources would have a dramatic effect on reducing the cost of space travel within cis-lunar space. Without the need for a vehicle to carry oxygen and hydrogen fuel to the lunar surface for its eventual return to orbit, manned missions to a lunar base could carry several metric tons of additional cargo plus additional passengers to the lunar surface instead of just a few hundred kilograms with crew as currently envisioned by the Constellation program. Lunar oxygen and hydrogen could also allow an Altair to be used as a reusable manned vehicle operating from the lunar surface to lunar orbit or from the lunar surface to L1.

A reusable single stage Altair crew transport vehicle could be fueled with oxygen and hydrogen from an L1 space depot for transporting passenger to the Moon and with in situ oxygen and hydrogen from the lunar surface for returning passengers to L1 requiring a much smaller vehicle that simply uses shorter cryogenic 0xygen and hydrogen fuel tanks.

A stretched Altair vehicle, using longer hydrogen and oxygen fuel tanks, combined with an ACES 41 tanker could be used to supply an L1 depot with oxygen and hydrogen produced on the lunar surface. Such a tanker could also be used to supply lunar bases not located near the poles with hydrogen.

So some day a paying tourist or a lunar lotto winner aboard a Falcon 9, Atlas V, Delta IV heavy, or a SD-CV could simply fly into orbit and dock with another ACES 41 (originally fueled with lunar oxygen and hydrogen at an L1 space depot) to travel to L1. At the Lagrange point, passengers would dock with an L1 fueled reusable Altair vehicle which would transport them to the Moon where they could perhaps stay at an appropriately mass shielded a Bigelow lunar hotel. The same lunar vehicle could be refueled with lunar oxygen and hydrogen for the tourist's return to L1 where they would dock with a CM-SM-ACES 41 equipped with an aerobreaking hypercone that would take them back to Earth orbit. There they would dock with a space capsule or Dreamchaser space plane that would finally return them to the Earth. That might be a very interesting vacation perhaps 15 or 20 years from now!

References and Links

1. Heavy Lift Launch Vehicles with Existing Propulsion Systems (Boeing Phantom Works)

2. Ambitious Ares Test Flight Proposed for HLV Demonstration

3. NASA Heavy Lift and Propulsion Trade Study

4. Completed SD HLV assessment highlights low-cost post-shuttle solution

5. ULA: Upper Stage Evolution

6. A Commercially Based Lunar Architecture

7. National Launch System

8. DIRECT

9. Boeing's New HLV Concept could be the DC-3 of Manned Rocket Boosters

10. No time for NASA complacency on crew safety

11. All of a Sudden, Everyone Wants to Be a Rocket Scientist

12. PWR Offers Shuttle Engine Alternative

Boeing's New HLV Concept could be the DC-3 of Manned Rocket Boosters

by Marcel F. Williams

On December 17th 1935, the Douglas Aircraft Company introduced an new airplane that revolutionized commercial air travel in America and around the world, the DC-3. Before the introduction of the DC-3, transcontinental flights entailed short range flights in smaller aircraft during the day combined with rail travel during the night. The DC-3, on the other hand, was able to cross the American continent completely by air with just three fueling stops and could take passengers from one coastline to the other in less than 18 hours. More than 16,000 DC-3s were built during its history. And 400 DC-3s are still in operation today!

Boeing Phantom Works has introduced a new shuttle derived heavy lift concept that is very similar to the DIRECT concept. An inline 8.4 meter in diameter core vehicle is used with either SSME (space shuttle main engines) or RS-68 engines. But instead of using the existing 4-segment SRBs (solid rocket boosters), there vehicle would use the 5-segment SRBs that are currently being developed for the Ares I rocket, a program that President Obama intends to terminate. However, unlike the DIRECT concept, Boeing has also proposed utilizing the inline booster without the SRBs as a crew only vehicle. Coupled with a manned space capsule and a stretched SM (service module), there would be no upper stage. And this would require the service module to perform the 2nd stage burn in order to achieve orbit.

NASA has recently (May 3rd) issued a request for information regarding potential heavy lift architectures that could be utilized by both NASA and commercial industries. Boeing's new heavy lift concept would seem to meet that criteria. With the SRBs and an upper stage, the core stage could be used by NASA or the DOD to lift up to 113 tons into low Earth orbit or send up to 45 tons to TLI (translunar injection). A dual launch scenario could transport up to 87 tons to TLI, a substantial increase over the 65 tons sent to TLI using the Ares I/V architecture.

But, additionally, without the SRBs and the upper stage, the LOX/LH2 core booster could be used by NASA, the military, or a private commercial company to transport up to 20 metric tons into orbit when utilizing a stretched SM (service module) to perform the second stage burn to achieve orbit. Such a hydrogen-oxygen fueled single stage booster could provide NASA and private industry with the simplest, safest, and most environmentally benign manned space rocket ever invented. And such a vehicle could usher in a new wave of space tourism!

There are polls that suggest that there may be thousands of wealthy individuals that would be willing to pay $20 million or more to fly into space to a space station. If such polls are even close to being accurate then manned launches for space tourism could greatly exceed government commissioned manned spaceflights to orbit with possible annual demands for space launches in the hundreds.

Such a high level of traffic into space would require the manufacturing of several hundred rocket engines every year. And such a high demand for rocket engines could introduce the serial mass production of rocket engines into US industries. Economies of mass production could substantially reduce the cost of rocket engines in the US. And polls have shown that lowering the cost of space travel would increase the demand for space tourism even higher!

A NASA heavy lift vehicle based on the same core vehicle would of course greatly benefit from the lower cost due to the high demand for the core booster by private industry. Eventually, the low cost of the core vehicle might become so attractive that NASA might contemplate replacing the SRBs with two additional core vehicles for heavy lift launches in a configuration similar to what is seen with the Delta IV heavy. This would be similar to one of the National Launch System (NLS) proposals of the 1990s.

It is also interesting that Boeing Phantom Works also produces the unmanned reusable X-37 experimental spaceplane for the US military which is currently in orbit after being launched into orbit by the ULA on top of an Atlas V rocket. Although the X-37 weighs about 5 metric tons, it has the basic Space Shuttle configuration. It uses a Rocketdyne AR-2/3 rocket engine, fuelled by JP-8 jet fuel and hydrogen peroxide. If Boeing decided to build a larger-- man rated-- version of the X-37, it could be the perfect compliment for the shuttle derived core vehicle also proposed by Boeing.


So America might retire one winged space vehicle, the space shuttle, while introducing a new winged manned space vehicle that can be used by NASA, the military, and private commercial industry. And a new era of manned space travel for government and private industry will have begun!

References and Links

1. Heavy Lift Launch Vehicles with Existing Propulsion Systems (Boeing Phantom Works)

2. Ambitious Ares Test Flight Proposed for HLV Demostration

3. NASA Heavy Lift and Propulsion Trade Study

4. X-37 Orbital Test Vehicle

5. Boeing X-37

6. Space Commercialization and the Lunar Lotto

7. National Launch System

8. DIRECT