Space Transportation Problems and Solutions
Concerned American Aerospace Engineers
February 2021
Coordinator: Don A. Nelson
caae@wt.net
Building a space cruiser like the Star Trek Enterprise should be the long-range goal of NASA. This goal can be achieved…No, this goal must be achieved if mankind is to have a future in space or even here on spaceship Earth!
The catalyst for achieving this goal is commerce. Commerce will be the driving force in establishing a sustainable space transportation system. Commerce will require that the space transportation system be affordable to make what all businesses need… “a profit”. The initial steps to a space cruiser Enterprise are:
· Political support.
· Reusable launcher with payload return capability.
· Space based tugs.
The technology exists for reusable launchers and space-based tugs. Political support will be the most challenging and “could” start with the Biden Administration.
Problems and Solutions for 21st Century Space Transportation
· The Space Launch System (SLS) will sooner or later be cancelled.
· Redirect the Space Launch System resources to space transportation technology programs.
· Endorse commercial space transportation.
· Develop Lunar/Mars commercialization with robotic vehicles.
· Establish a long-range Space Transportation Plan
· Build defense system for the Asteroid/Comet threat.
NASA has never a serious effort to reduce launch operation cost. Cost plus fix price contracts have resulted in excessive development and operations cost. In the last 10 years, seven major programs have been cancelled. One, the Constellation Program spent $11b before if was cancelled. Its replacement the SLS has reportedly already spent $17b. In addition, there are unsolvable SLS/Orion safety issues that NASA management and the NASA Aerospace Safety Advisory Panel has ignored.
Cancelling the Space Launch System
It is time to face the reality that NASA’s Space Launch System (SLS) cannot meet the goal of being a safe, affordable, and sustainable human space transportation system. Consider the following:
1. With a capability of only one to two launches a year, the labor cost alone will be over $1 billion per year and estimates of $3b per launch is not unreasonable.
2. The SLS/Orion is an “expendable” launch system where every mission will be an initial flight test of the launcher and crew vehicle. Expendable launch systems have a historic failure rate of 2 to 10 percent, primarily caused by manufacturing errors. This failure rate possibility is unacceptable for a human manned mission as complex as the Artemis Program. As seen in the SLS image above there are six major components plus the components of the lunar lander that would have potential manufacturing errors.
History of Launch Failures
FAA Data
Of the 12 manned Apollo mission there were 4 critical manufacturing errors failures:
· The crew was lost in the Apollo 1 fire.
· An Apollo 13 Saturn V engine cut-off early.
· The Apollo 13 crew was saved by using the Lunar landing vehicle to return the crew for a safe ocean landing.
· An Apollo 15 disaster was averted because the sea was calm when it splashed down after a parachute failed to open.
The same grim safety occurrences can be expected for the SLS/Orion and lunar landers.
3. NASA has been unable to achieve their lunar mission goal of returning 220 pounds of payload. One report indicated the payload return was only 57 pounds. With a lunar surface stay time of 7 days and only five EVAs, the expected scientific value of an Artemis mission is extremely questionable.
The SLS program will be cancelled…it will be cancelled in the near future because the President and Congress finally recognizes that it is unsafe and unaffordable, or it will be cancelled after we lose another crew!
Redirect the Space Launch System Resources
There is no long-term future for the SLS/Orion. It is prudent to accept this inevitable outcome and redirect the funding to technology programs that support the development of a space transportation system using reusable space vehicles. These programs would be conducted at space centers in congressional districts now supporting the SLS/Orion programs.
Technology programs considerations are:
Lightweight materials.
In-orbit system repair and replacement.
Automated flight and health monitoring systems.
Space based propellant farms.
Crew escape and survival modules.
Improve battery storage lifetime.
Standardized avionics subsystem.
Advance thermal protection systems
Electric propulsion
Hybrid rockets
In-Situ resources
In space manufacturing
Propellant-less Propulsion
There is an unending number of research programs that go unfunded. Following are candidate technology programs that should be structured to support development of commercial reusable space vehicles. The spinoff uses of these technology programs has the potential for vast economic benefits. It is a government jobs program that pays dividends to the taxpayers!
Composite Materials:
Composite material can be developed to reduce airframe weight as was accomplished for the Boeing 787. Composite materials can reduce the space shuttle orbiter weight by 20 percent (approx. 15,000 lbs.). Initially this weight saving should be used to reduce landing loads and the size of the external tank or elimination of the tank. Composite materials are expected to reduce the maintenance costs.
NASA had a composite propellant tank program. This program needs to be restarted.
Modular Flight Subsystems:
Subsystems must be a modular concept, designed for unconstrained replacement. The spare parts operation must be based on modular replacement of the subsystem. Modular replacement is required to reduce the time for replacing flight failed subsystems from days to hours. Modular replacement designs must consider launch pad and on-orbit replacement of failed equipment.
Orbiter Propulsion:
All Hydrazine is removed from the freighters and tugs. The attitude control propellant could be replaced with a “green” propellant such as AF-M315E. The orbital maneuvering system for major altitude changes could be a hybrid engine with liquid oxidizers and a solid fuel such as hydroxyl-terminated polybutadiene (HPPB). These fuels decrease processing time and increase safety. The Dream Chaser hybrid rocket motor is being considered to replace the orbiter’s hydrazine OMS.
Main Engine:
The existing supply of SSME engines may not all be used for the Space Launch System. If not available, new engines can be built. For future development, the engine could adopt extensive use of integrated health monitoring and single cast construction of large components. High pressure pumps could be incorporated that can be flown 50 times before overhaul. Studies have projected that an advanced engine can be turned around in 58 hours as compared to the current time of 160 hours.
There are other potential engines to be considered: the SpaceX Raptor and the Blue Origin BE-4. However, these engines are still in development. The RS 25 engine will be more expensive ($50m est.) but is more efficient with the highest vacuum specific impulse of 452.
VASIMR plasma rocket and NERVA nuclear engine.
Electrical Power System:
Consider solar arrays and ion batteries and an Electric Auxiliary Power Unit (APU) system designed to replace the Orbiter’s existing Hydrazine APU. The Electric APU consists of a battery, associated 270-volt power, distribution and control, electro-hydraulic drive unit, and cooling system. Electromechanical Actuators (landing gear, body flaps, elavons, gimbals) will be designed for those functions.
X-37B Solar Array Electric Auxiliary Power Unit
Integrated Vehicle Health Management System (IVHM):
A major contributor to the high costs of current space vehicle systems is the operations, maintenance, and infrastructure portion of the program’s total life-cycle costs. Incorporation of IVHM with distributed remote health nodes, fiber optic distributed strain sensor, and fiber distributed data interface communications components will result in significant program life cycle savings by improving reliability and lowering operational costs. Computer technology has advanced to the state that an onboard IVHM computer system can verify the status and control all vehicle systems. It has been proved to be extremely effective on modern aircraft and spacecraft. The ground and flight software developed for the Lockheed Martin VentureStar and X-37B could be a baseline design for reducing the cost and development time of the IVHM system.
External Tank (ET):
The long-term goal is to eliminate the need for an external tank. However, currently this is not possible. Therefore, manufacturing cost, not payload to orbit will be determining factor in the design of the freighter external tank. The cost of the shuttle external tank was driven by the objective to put more payload into orbit.
Redesign considerations for cost reductions:
· Stainless steel construction and remove all light-weight components.
· Remove foam insulation (see orbiter TPS).
· Investigate moving LOX to aft section and moving LH tank to forward location.
· More than one tank manufacturer.
· Locate tank facility near launch site.
Thermal Protective System (TPS):
The NASA Space Shuttle TPS is not acceptable. However, the TPS is not believed to be a development issue with the current available materials. Use of metallic tile, mechanical fasteners, carrier panels, carbon-carbon, rigid ceramic and other current technology will be considered. The TPS must be able to withstand impacts and/or be repairable on-orbit. The vehicle health monitoring system will monitor the TPS for any breach. On orbit repair of TPS will be developed.
Other TPS considerations:
· Toughened unipiece fibrous re-enforced oxidation-resistant composite, (TUFROC), to cover the wings’ leading edges.
· Toughened unipiece fibrous insulation,” (TUFI), to replace ceramic tiles and reduce weight.
· Design a robotic flight vehicle system to repair on-orbit TPS failures.
X-37B Nose Cone TPS Configuration
Lockheed Martin VentureStar TPS
In-Flight TPS Inspection and repair capability:
In-flight inspection using the integration of thousands of sensors into a pattern of fibers located in the TPS will provide real-time structural health of the freighter. Any breach in the TPS will be repaired by an on-board free fly spacecraft designed for multi-purposes repair. TPS repair kits fall into two basic categories, mechanical or chemical. Mechanical repairs systems rely on prefabricated materials and fasteners. Chemical repairs rely on materials that are applied in a raw form and develop into a chemical adhesive bond to the TPS.
Aero-brake re-entry systems:
Deep space missions could be supported by a thermal aero-brake entry system. The aero-brake conducts several skip entry maneuvers to slow to low earth orbit velocity where a commercial freighter would rendezvous with it for cargo retrieval and resupply for next mission.
Passenger Escape Pod:
Passengers will be
transported to and from space in pods. Escape pod weigh is estimated at 700
pounds per pod. The pods provide protection for all phases of flight.
At launch pad abort and lower altitude escapes, a ballute deploys to slow the
pod for parachute deploy. The pod’s life support system provides on-orbit safe
haven in the event the cabin pressure is breached. Target lifetime for life
support is 20 days to allow for on-orbit rescue. Pods are located behind the
nose cone heat shield wake to reduce excessive thermal loads in the event of a
Columbia type entry failure. The pod is also equipped with a heat shield
system. The pod must be a “smart pod” ... it must have knowledge of the
environment.
Endorse Commercial Space Transportation
Public-private partnerships and fixed-price contracts like those for commercial crew program have been shown to work. There is sufficient technology for NASA to issue a fixed-price contract request for proposal for commercial launch services that provides rapid launch turnaround and heavy payload return capabilities like that of the decommissioned space shuttle. Payload return capability is a mandatory requirement for a commercial space transportation system.
The business model to be considered is that of Lockheed Martin’s VentureStar commercial launch vehicle fleet. Lockheed Martin proposed to build and operate a minimal commercial fleet of vehicles. NASA and other U.S. government customers would guarantee a specific number of payloads (launches). Unfortunately, the VentureStar had unsolvable development problems and never obtained operational status.
This is a similar business model to that the USAF has with United Launch Alliance. However, the extreme operating cost and low flight rate of their expendable launch vehicles has made this a very expense business contract.
Commercial Launch Vehicle Candidates
The most promising option is the decommissioned space shuttle configuration and use of existing technology to correct its deficiencies. It is important to remember that only a reusable space shuttle had the payload return to earth capability. This is a mandatory capability for any commercial space operation!
The space shuttle freighter (CSS) would use the decommissioned orbiter airframe profile. Redesigned low-cost external tanks and solid rocket boosters would be used until technology is available to eliminate these systems. Crews will be flown only on missions requiring their presence for mission support. For these missions, they will be provided escape pods which provides protection for launch, on-orbit, and entry anomalies. Launch pad assembly of the freighter will reduce operations cost and turnaround time. Rapid turn-around is a unique freighter feature which reduces operation’s cost, provides the capability for timely intercepts of threating asteroids/comets, and supports USAF rapid deploy missions. The launch cost will be significantly lower than those of a similar payload capacity expendable launch vehicle, primarily because of eliminating the manufacturing of expendable stages, capability to increase flight rate, and lower insurance costs because of the increase reliability.
No NASA support will be required for the operations of the freighter or space-based vehicles. NASA’s role in space transportation will be to develop advanced technologies and concepts for the space freighters and space-based vehicles needed for near earth and deep space operations. NASA, however, will/or can oversee research space probes delivered by the transportation system.
Design Reference Mission:
· Deliver and return 15 metric tons to and from a circular orbit of 240 nm at an inclination of 28.5 degrees.
· All mission phases conducted by autonomous operation with ground control backup flight guidance.
· Provide escape pods for up to 4 passengers. Passengers will have no flight control authority.
· Provide 4 days nominal on-orbit operation plus 8 days in power down mode for contingency passenger retrieval. Dormant (no passengers) on-orbit systems will be designed for 60 days in gravity gradient attitude for repair or retrieval of disabled freighter.
· Orbiter return to launch status will not exceed five days.
Business Model:
Development and operation estimates have been made for the commercial) freighter, using NASA data. It was estimated that a fleet of 3 launchers could be developed in the private sector for $9 billion. Annual operations cost was estimated to be $820 million.
The plan requires that the government (NASA/USAF) annually purchase enough launches to meet the space launch company operations expenses. Any launch position not needed by the government would be released to back to the freighter operator for commercial flights. In 2018 there were 35 launches that could have been flown on the freighter. The freighter operator would only have to capture 17 to achieve a break-even target goal of a $50 million launch operation cost. With the freighter unique capability of reuse, low operations cost, and providing payload return, this is a very achievable goal!
NASA can initiate the freighter program by issuing a Request for proposal (RFP) for launch services. Initially the freighter contractor would be asked to provide launch service to LEO. Expanding the system to support deep space-based vehicles would follow. NASA would have a backup to the Space Launch System without effecting the progress or present a challenge to those who still believe this failing program will prevail.
SpaceX Starship
The SpaceX Starship is a serious contender for a reusable commercial launcher. It is in development, but this engineer believes that it faces complex challenges with its propellant boundary-layer entry thermal protecting system.
Chinese Tianjiao – 1
It is believed that the Tianjiao – 1 has already completed its first test flight. Regardless, it signifies that to be a leading space-faring nation you must have a space shuttle to return payloads from orbit.
Develop Lunar/Mars Commercialization
There will never be a sustainable Lunar/Mars community until there is an affordable and safe deep space transportation system. The SLS is neither. We could not have established scientific bases in the Antarctica if the transportation cost would have been $3 billion per flight. Robotic science rovers are currently the only viable option for Lunar/Mars exploration. These rovers should also explore for potential commercial endeavor. There may be no requirement for human surface interface. Therefore, manned deep space transportation endeavors should be postponed until a human surface interface need is established.
Asteroid/Comet Planetary Defense System
“Americans would rather stop asteroids from hitting Earth than go to the moon or Mars, according to a poll published last June by the Associated Press-NORC Center for Public Affairs Research at the University of Chicago. The potential for a cataclysmic asteroid impact on our home planet is so credible that NASA established a Planetary Defense Coordination Office in 2016 to coordinate efforts of U.S. agencies, international counterparts, and professional and amateur astronomers around the world. The European Space Agency also established a Near-Earth Object Coordination Centre that conducts searches for near-Earth asteroids.” (AIAA , Aerospace America Jan. 2020)
Directed by Congress in 2005 to discover at least 90% of near-Earth objects 140 meters across; NASA has discovered less than half of the estimated 25,000 objects. Worst yet are the unidentified small basketball size objects with iron cores that can do significantly more damage than some of the 140 meters objects. NASA management’s position is that a big asteroid/comet fireball “is only expected about two or three times every 100 years.” However, their own data indicates an alarming number of recent near misses. It only takes one to…
NASA JPL Chart
The Asteroid/Comet defense system has three requirements; detect the threat, determine the composition of the object, and destroy or deflect the object. If the decision to develop commercial reusable launchers and space-based vehicles is approved, then the only missing requirement is the is a detection system.
There are several options for asteroid-detection satellites. NASA, in 2015 proposed a space telescope called Near Earth Object (NEO)Cam for study and after five years decided to investigate another spacecraft NEO Surveyor. It would survey the sky for potentially hazardous asteroids and gather infrared light to characterize their physical properties, such as diameters.
Another more cost-effective option would be to place asteroid detection sensors on earth orbit satellites with other functions such as communications or ground mapping. Consider, for example, Europe’s Gaia satellite which is in the process of mapping the positions and movements of the stars to create a 3D map. Gaia also watches for asteroids, and it has discovered three previously unknown ones. This supports the notion that asteroid detection can be one of many functions of a satellite mission and would not have to drive up manufacturing and launch costs. Gaia also shows that asteroid detection can and must be an international project.
Space Transportation Plan
There has never been a long-range plan for the development of space transportation systems. The following chart outlines the development and operation that enables the construction of a space-based fleet. The stair step approach provides a long-range plan for obtaining needed technologies and space vehicle development. Each step is a building block for the next phase of development. It allows the next phase to begin before the previous step is operational. For example, the space-based transport stage (Trans Stg.) commonly referred to as a space tug, can be started before a commercially developed and operated launch freighter(s) becomes operational. The Lunar Transfer vehicle can be used as cis-lunar transfers or asteroid/comets interceptions. The modular system design permits in-space subsystems upgrades.
The Space Transportation Plan for the 21st Century
“To get somewhere… we have to know where we’re going!”
Space Based… Space Tug to Space Cruiser
The initial space-based vehicles would be small, unmanned vehicles supporting robotic missions. The development schedule for large crewed spaced based vehicles will accelerate or decrease as the funding and needs for space exploration requirements dictate.
Space based tugs must be a top priority for the space transportation system. They are a key factor for reducing mission cost and increasing mission success. Tugs can be supplied by reusable launchers. Tugs can support near earth, lunar, and deep space missions. The first step to a “Star Trek Enterprise” space cruiser is the unmanned space-based tug. NASA’s future is in the development of these space-based vehicles to be operated by the commercial sector.
These future space tug concepts will remain paper studies until the launch cost to orbit is significantly reduced. There must be a defined affordable launch mass capability before any deep space transportation vehicle can be developed.
Justifications
for space-based vehicles:
1.) Space based vehicles are the logical and mandatory requirement in the
establishment of a baseline concept for cost-efficient advanced space
transportation systems. Lifetime of these vehicles would be expected to be 10
to 20 years and therefore would significantly reduce the cost of deep space
transportation.
2.) Development of space-based vehicles provides an exciting and meaningful
endeavor for NASA and its contractors.
3.) Space based vehicles will reduce the orbital debris problem.
4.) The inert weight of the expendable upper stage would not have to be
orbited.
5.) Provides a test platform for testing and recovering hazardous advance
concept space engines (nuclear, toxic, etc.).
6.) Of interest is the capability to provide affordable access to unmanned
space commercial laboratories and space manufacturing facilities.
Space-Based Tug/Cruiser with Nuclear Propulsion
NASA Technical Reports Server (NTRS)
Launch Market for Commercial Launchers:
The commercial shuttle/tug has the potential to increase the launch market by offering the unique capability of satellite on-orbit checkout before release and returning faulty satellites for repair. Once the space tug is operational, satellites can be serviced on-orbit or retrieved. Tourist flights also have the potential to reduce cost of cargo delivery.
It is recognized that economic conditions will dictate the launch market; however significantly lowering the launch cost will attract other unidentified users.
· Is the SLS cost and expected loss of crew worth 58 pounds of lunar rock?
· Which has the most potential…SLS or advanced technology programs?
· Commercial or NASA launch mission operations?
· Endorse Lunar/Mars Commercialization?
· Ignore asteroid/comet planetary defense?
These are the questions that must be addressed. Continue the same path of repeated failures, or change directions by supporting commercial space endeavors, advanced space technologies, and asteroid/comet planetary defense? The future of mankind may very well be determined by this decision.
If you share these concerns and want to support this effort contact the CAAE and/or your congressional representatives at: Contacting Congress
Coordinator’s Biography and Contact Information
Don A. Nelson is
an aerospace consultant and writer. Mr. Nelson retired from NASA in January
1999 after 36 years with the agency. He participated in the Gemini, Apollo,
Skylab, and Space Shuttle Projects as a mission planner and operations
technologist. Mr. Nelson was a supporting team member for the first rendezvous
in space, first manned mission to the moon, first manned lunar landing, and the
first flight of the Space Shuttle. During his last 11 years at the NASA Johnson
Space Center, he served as a mission operations evaluator for proposed advanced
space transportation projects. Mr. Nelson is a graduate of Southern Methodist
University School of Engineering. He is a certified private pilot and holds a
Phase VI Pilot Proficiency Wings award from the Federal Aviation
Administration.
Mr. Nelson is the author of: “NASA New
Millennium Problems and Solutions” and “The NASA letters.”
For information or to offer support contact:
Email: caae@wt.net
Mail:
Nelson Aerospace Consulting
1407 Moller Rd
Alvin TX 77511-3248
The NASA Letters: Nelson, Don A.: 9781542763882: Amazon.com: Books
Amazon.com : NASA New Millennium Problems and Solutions”