10/28/2008
Eckart IV:
Fundamentals of Life Support Systems
Learning Objectives
Early High Altitude
Balloon Life Support System Evolution
1927 –
1934 – Explorer I high altitude H2/air balloon exploded. Capt. Stevens and his 2 crewmates barely escaped by parachute due to hatch egress difficulties. (Explorer II hatch was widened and gas switched to He)
1935 – To ensure that it attained a record altitude (72,395 feet), Explorer II’s balloon was enlarged, the crew cut from 3 to 2, and its scientific payload (the rationale for the flight) was halved…
Where does Space
Begin?
50 miles (264,000 ft or 80 km) recognized by the USAF as being in space
- Astronaut wings awarded to three civilian research pilots who flew the X-15 into space in the mid-1960s (8/23/05)
62 miles (328,000 ft or 100 km) internationally accepted boundary of space set by the Fédération Aéronautique Internationale
‘Space Flight Pioneers’
Before humans
actually went into space, one of the prevailing theories of the perils of space
flight was that humans might not be able to survive long periods of
weightlessness. For several years, there
had been a serious debate among scientists about the effects of prolonged
weightlessness.
American and Russian
scientists utilized animals - mainly monkeys, chimps and dogs - in order to
test each country's ability to launch a living organism into space and bring it
back alive and unharmed.
On June 11, 1948, a
V-2 Blossom launched into space from White Sands,
The V-2 rockets
carried Air Force Aero Medical Laboratory monkeys named Albert I, II, III, and
IV high in the atmosphere to see how they might withstand space conditions. All
of the monkeys survived the upward trip, but were killed when parachutes failed
to open and the nose cones impacted the ground.
On August 31, 1948,
another V-2 was launched and carried a mouse that was photographed in flight
and survived impact. In May 1950, the
last of the five Aeromedical Laboratory V-2 launches
(known as the Albert Series) carried a mouse that was photographed in flight
and survived impact.
On September 20,
1951, a monkey named Yorick was recovered after an Aerobee missile flight of 236,000 feet at Holloman Air
Force Base,
On Nov. 3, 1957, Sputkik II carried the first animal launched into orbit (Laika) using an open-loop LSS
The first
The subsequent
success of Ham’s Mercury capsule flight led directly to the launch of Alan
Shepard on
The
http://history.nasa.gov/animals.html
Human Spacecraft and
Life Support System Highlights
Vostok 1 (April 12, 1961)
Voskhod (1964-65)
Mercury Program (May 1961- May 1963)
Gemini Program (March 1965 – November 1966)
Apollo Program (January 1967 – December 1972)
2 LSS’s (CSM and LM independent)
· Lunar Module (2 people) (5 m3), stowed water, no overboard urine venting, iodine
· Command and Servicing Module (CSM), 3 people, (7 m3), on orbit fuel cell water production, cholorinated water
Soyuz Program (1960’s and 70’s)
Salyut 1 (1970’s and 80’s)
Skylab (May 1973 – February 1974)
Apollo-Soyuz Test Project (ASTP, July 1975)
Orbiter (71 m3, approximately 68,000 kg)
ET and SRB’s, along with the Orbiter, make up the overall Space Transportation System (STS)
Spacelab (~70 m3)
SPACEHAB (~31 m3)
MIR (1980’s and 90’s into early 2001)
· Launched February 19, 1986
Mir Space Station - Base Block, Kvant 1, Kvant 2, Kristall, Spektr and Priroda (~90 m3 ea.) sea level pressure, up to 6.8 psia ppO2 (21-40%)
Russian Space Shuttle Buran
Shuttle-Mir Program (February 1994 – June 1998)
International Space Station (ISS)
ECLSS Primary Design
Goals
Goal of a spacecraft ECLSS is to provide a controlled, physiologically acceptable environment
Overcoming the Space Flight Environment
Vacuum à Pressure Shell
Weightlessness (also Launch Loads / Variable g) à Design
Micrometeoroids à Shielding
Radiation à Shielding (active vs. passive) and Mission Design factors
Temperature Extremes à Insulate / Radiate
Satisfy physiological needs of the crew
Metabolic (oxygen, water, food and waste)
Environmental (pressure, thermal control)
Provide resources for hygiene, medical and science needs and other systems (e.g. EVA) and leakage
Crew = resource consumer / waste producer
ECLSS = resource provider / waste collector
Human
I/O = ECLSS O/I
Overview
Humans are essentially open systems wrt mass and energy
Earth is ‘basically’ closed wrt mass, but open wrt energy
Traditional components of an LSS – air, water and food provision and waste collection
Additional factors – vibration, noise, temperature, pressure, radiation protection, EM exposure, gravity-dependent issues, etc.
5 Primary LSS Components (per the text)
1. Atmosphere Management (CO2, O2, N2, TCC, THC, FDS)
2. Water Management – potable, hygiene and recovery
3. Food Supply – provision and/or production
4. Waste Processing – collect, store, process from trash, water and food waste
5. Safety – FDS, radiation shielding
I would substitute ‘Health and Habitability’ for #5
(moving FDS and shielding to atmosphere / pressure vessel management) and add a
6th category
5a. Health and Habitability – emergency treatment, exercise devices and human factors
6. EVA
Basic Options for
Meeting the Requirements
Launch all consumables at the start
Periodically resupply consumables
Recycle consumables in flight
Utilize in situ resources (ISRU)
LSS Classifications
Regenerative
Non-regenerative
Open loop
Closed loop
NOTE: The above 4 options must be followed by the
phrase ‘with respect to’ and explained in appropriate context of consumable mass,
energy, technology, etc.
Physico/Chemical
Biological
Hybrid systems
Radiation and debris shielding can be included as an ECLSS function, but is usually considered part of spacecraft structures
Longer term concerns
Human
Factors / Psychological and
Biomedical
Countermeasures
Atmosphere
Provide Oxygen
3.1 psia ppO2 (160 torr) = Normoxic
21% of 1 standard atm (14.7 psia or 760 torr)
Too little O2 = hypoxia
Too much O2 = toxicity
Remove CO2
Too much = blood becomes acidic – no O2 – fainting
Too little = alkaline – hyperventilation – fainting
CO2 in the 2000-3000 ppm range in the orbiter
10,000 (1%) – safety limit
Engineering / Physiology
Atmosphere Trade Variables
Normoxic baseline (may consider hyperoxic or hypoxic limits?)
Minimize flammability (<30% O2)
Sufficient density for convective cooling
Efficiently remove
CO2 and Humidity
Minimize risk of DCS during EVA (caisson disease, the Bends)
Sufficient pressure shell structural strength
Compensate for cabin leakage
Maintain spacecraft thermal equilibrium between heat generated/absorbed and heat radiated to space
Spacecraft attitude and structural / surface properties à thermal absorptivity / reflectivity / transmissivity effects
Overall cabin set
point - heat load / forced convection via cabin air or cold plate conduction /
water / freon / space
Individual heat
balance - clothing, sleeping bag, directed airflow
Also must account
for humidity control - water separation / collection / stowage / dump / recycle
Water
Potable water has highest standards
Iodine or silver biocide
Monitoring
pH, ammonia, TOC, electrical conductivity and microbial concentrations (CFU’s)
Color, odor, turbidity, foaming and heavy metal accumulation
Hygiene water standards less stringent, but total mass may be greater
Total estimated consumables per person per year (illustrated value range adapted from Eckart, 1996 and Clement, 2003)
Note: For actual ‘design to’ values, consult and cite a source such as NASA’s Baseline Values and Assumptions Document (BVAD)
Food = 219-303 kg (~3x body mass)
Oxygen = 226-292 kg (~ 4x body mass)
Potable Water = 1132-1300 kg (~17x body mass)
Hygiene Water = 2000 kg (?)
Laundry Water = 4500 kg (?)
Up to ~8400 kg
total consumables per person per year (for a full up laundry and hygiene
system)
Water = Greatest single
mass consumable in general
(~7800
kg/person/year in this case, or 2058 gal, which is still only ~5.6 gal/day)
à treatment technologies, mass, power, processing
time, consumable mass, etc.
Food
Provision, storage and preparation
Not always considered part of ECLSS
Processing ranges from ready-to-eat or rehydration to grow, harvest, modify and cook
USDA guidelines met for balanced meals
there’s a lot of current debate about these guidelines
Short term flight probably not an issue
Current criteria
Minimal in-flight preparation
Minimal waste
Ambient stowage
Good taste
Also need to consider for longer durations
Stability
Variety
Production during mission
Waste
Collect, transport, store, stabilize, treat or dispose
CO2, Urine and Feces, non-edible biomass, non-recoverable liquids/solids, wet/dry trash
Becomes increasingly difficult to define ‘waste’ as system closure level increases
Habitability Factors
Various aspects of the environmental design requirements driven by human needs to maintain physiological and psychological well being
Habitability encompasses:
Life Support Basics (e.g. air, water, food, etc.)
`Human Factors (e.g. workstation layout, lighting, etc.)
Short term
climate, illumination, radiation, odor, noise, vibration, interior layout, hygiene, etc.
Long term
crew composition / interpersonal dynamics, crisis management, motivation, communication, meal periods, privacy, mental care, off duty activities, etc.
Basic drivers in systems and architectural design and development processes for human spacecraft
Key ECLSS Design
Drivers
Human I/O’s
Environments Encountered
EVA Plans
Launch Mass vs. Performance and Risk Factors
ECLSS Design Process
Development of a S/C LSS is an iterative process involving functional definition, technology evaluation, sys configs, integrated analyses (experimental and modeled) and ultimate testing and flight qualifying of HW and SW
Initially – simplified scenarios used to evaluate requirements and constraints
Top level trade studies next conducted using simple models of technology candidates to identify most suitable combinations given mission requirements
Performance and Risk Factors are then evaluated by testing at the component / subsystem / system levels
Finally, human flight qualification process starts
See Figure IV.1, pg 84 – Life Support Functions and Interrelationships
See Table IV.4 gives good summary of “functional” requirements and their associated break-even times, for a regenerative LSS without imposing design solutions
Provision of O2 always
CO2 reduction months-years
Provision of potable H2O always
Provision of hygiene H2O months-years
Urine processing months-years
(Solid) Waste processing years
Provision of food always
Table IV.5 now brings in candidate solutions
Likewise, tables IV.6 and IV.7 similarly address need based on duration and introduce additional technologies
In both cases, however, the requirements are not clearly defined at the “functional” level
Factors Affecting
Closure must also be traded against factors such as power and volume (by ESM) and cost (budget).
Other variables: Crew size, mission duration, leakage, resupply capability (STS, ISS, moon, Mars), power availability, volume fraction allocated in the S/C, launch cost ($10k/lb currently), g-dependencies, safety / reliability, in situ resources, etc.
Reliability and Safety Concerns
Redundancy and Contingency Philosophies
Developing an ECLSS
Functional Schematic
Meet requirements for environmental control parameters (non-consumables) and human I/O’s (consumables)
ECLSS Functions
Atmosphere
Control total cabin pressure
Control gas composition / partial pressures
- Provide Oxygen (and any necessary buffer gas)
Control temperature
Remove humidity
Remove CO2 and TC’s
Provide ventilation
Monitor atmosphere parameters
Provide fire detection / suppression
Water
Provide potable (and potentially hygiene water)
Store, distribute and monitor quality
Collect condensate from atmosphere
Food
Provide, store, prepare
Waste
Collect, process, store/jettison any non-recoverable waste streams