Midterm Terms Flashcards
Why send humans to space (vs robots)?
Flexible decision making (S-band antenna example)
Research subjects (test human affects in space)
In-situ operation efficiency
Inspiration for next generations
Survival of the human species
Why NOT send humans to space?
Increase reliability & safety requirements
Life support requirements (oxygen, etc)
First human in space
Yuri Gagarin - Apr 12, 1961
One orbit, ejection seat w/ parachute
First woman in space
Valentina Tereshkova - Jun 16, 1963
Vostok 6
First spacewalk
Alexi Leonov - Mar 18, 1965
Voskhod-2
Russian Spacecraft
Voskhod 2 (1964-65); 2-3 crew
Soyuz; 3 crew; 14.7psi
Project Mercury
100% O2, 5psi; 1.02m3 volume; 1 person crew
First American in space
Alan Shepherd - May 5, 1961
Gemini
2 crew; 100% O2, 5psi 1.56m3 volume
Demonstrated rendezvous & docking (1965-66)
Apollo
3 crew; 100% O2, 5psi; Lunar - 4.5m3 vol/Command - 6m3 vol
Human voyage and landing on the moon
Space Stations
Salyut - first space station Apr 19, 1971
Skylab - first US space station May 14, 1973
Mir - 1986 thru 2001
ISS - 1998 thru current
Tiangong Space Lab - 2012 & 2021 (core module)
US Space Shuttle program
1981-2011
135 flights
3 main assemblies - orbiter, solid rocket boosters, external tank
Columbia, Challenger, Discovery, Atlantis, Endeavour
Up to 8 crew
Needs, Goals, & Objectives (NGOs)
Need - Why are we doing this? Drives everything
Goals - High-level milestones to fulfill need
Objectives - Definition of project success (specific)
Design Reference Mission
DRM will be provided after defining NGOs for a human spaceflight mission
Outlines functionality expected of crew transportation system
Top-level mission scenario from start to finish
Broad requirements generated by NASA to industry
Human rating
Requirements specific for human health & safety
Defines human interactions w/ the vehicle
Established after 1990s shuttle disasters
Increased focus on operability, human performance, & health
Human Rating Tenets
- Accommodate the physiological needs of the crew
- Utilize the crew’s capabilities
- Protect the crew
NASA Human Rating Standard (NPR 8705.2C)
Human rating certification for hazard analysis, failure modes, probabilistic safety, flight test plans, etc.
Provides requirements for system safety, crew control, and crew survival & aborts
Guidelines for Design of Human Space Systems
- Design for minimum risk (eliminate hazards)
- Incorporate safety devices (add automation or indicators)
- Provide warning devices (signals & detect hazards)
- Develop procedures & training
Concept of Operations (ConOps)
Verbal & graphical content
Overall picture of operations
Established early in the system design process
Forms a basis for mission planning
ConOps Content
Description of major phases
Operational scenarios and/or DRMs
Operational Timelines
Communications Strategy
Command & data architecture
Operational facilities
Integrated logistics support
Space environment effects on humans
microgravity
radation
pressure (ppO2)
Temp/thermal control
Psychological
Diet & nutrition
Electric shock
Weightlessness adaptation
Most effects are adapted while on orbit and become harmful (maladaptive) once returning from space
Weightlessness Effects on Humans
Short term
Fluid shift, neurosensory adaptation
Long Term
Bones loss, muscle atrophy, anthropometry, blood volume decrease, cardio vascular adaptation (decrease), visual acuity
Fluid shift (short term)
Compensatory down-regulation of plasma volume associated with central and intracellular fluid shift, begins on launch pad and in earnest on orbit, stufiness, potential effects on cerebral venous drainage
Neurosensory response (short term)
Sense of position/motion shift
Space Adaptation Syndrome - onset after MECO
lasts about 1-3 days; rarely longer
Anthropometry (short term)
Neutral body posture, decreased abdominal girth, increased chest diameter, increased standing height, change in line of sight vs. 1g environments
Blood Volume & Cardiovascular Changes (Long Term)
Blood decrease in plasma volume (10-15%) & red cell mass (10-12%)
Aerobic capacity diminished inflight
Bone loss & muscle atrophy (long term)
Bone & muscle loss
Early ISS 1-2% per month
2-2.5x time payback
Bird legs - disuse atrophy
Weight machine countermeasures to reduce leg atrophy
Visual Changes (long term)
Spaceflight associated neuro-opthalmic syndrome (SANS)
Swelling of optic nerve, globe flattening, refractive error shift
Medical monitoring after career - long term implications unknown
Venous Thrombosis (long term)
Stagnant or retrograde flow in the internal jugular vein which may lead to thrombosis (blood cot) long term
Post landing (microgravity) adaptation (long term)
Hypovolemia - 12-15% less blood volume
Anemia - 10-12% less blood cells
Aerobic deconditioning - 15-20% deficit
Increased spinal length (6%)
Deconditioning (long term)
Entry adaption syndrome
Postural instability
Orthostatic intolerance
Impaired fitness
Decreased bone density
Effects of partial gravity
Mostly unknown/TBD
Walking becomes more natural
Fluids separate & natural convection
Mars gravity (1/3g) Lunar (1/6g)
delta Pressure / delta Time
10,000ft pulmonary barotrauma (rupture of cardio walls)
10-18Kft Hypoxia (low level of O2 in tissue)
18,000ft decompression sickness (DCS)
63,000ft Ebuillism (spontaneous phase change from liquid to vapor/gas)
Space Radiation Events
Number 1 issue beyond LEO
Solar wind - plasma with protron/electron gas
Solar Particle Events - solar storms
Trapped Radiation in Van Allen Belts
Galactic Cosmic Rays - highly energetic H & He ions
Radiation Effects on Humans
Acute (inc by dose) - retinal flash, burns, nausea/vomiting, sterility, hair loss, coma/death
Chronic (inc by dose) - cataracts, immunological dysfunction, premature aging, cancer risk
Radiation during 2.5yr Mars mission
~1Sv (Sievert) which is about 5% increase in fatal cancer
Sustained Linear Acceleration - +Gx Forward
Sustained G in the linear direction are much higher than other axes
Primarily limited by respiratory problems (lungs)
+2Gx tolerable up to 24 hrs
+3-6Gx mechanical compression of chest wall/blurred vision; lower tolerance period
Sustained Linear Acceleration (+Gz) Upward
Upward acceleration effects due to hydrostatic pressure change (up and down in elevator), each +Gz increases blood pressure in brain by 22mmHg, limited by visual
G-LOC: blackout after ~5secs at 4.5-6Gz
Shuttle reached maxGz ~1.5-1.7G in 20mins post-launch
Sustained Linear Acceleration (-Gz) Downward
-1 equivalent to hanging upside down
-2 to 3 throbbing headache, swollen eyelids
-4 to -6 >6 secs causes mental confusion & unconsciousness
Shock or Impact
Impact acceleration may occur during launch/descent
Injury depends on magnitude, restraints, person
Dislocation, death, fracture, etc`
G Tolerances
+-Gx (chest) 20g amplitude rate 10,000g/s
+-Gy (side) 20g amplitude rate 1,000g/s
+-Gz (spine) 15g amplitude rate 500g/s
Regolith (Dust) Effects
Mars and Moon are covered with loose/powdery dust
Smaller particles can jam humans/machines
Respiratory irritation, chronic pulmonary diseases, irritation
Launch Escape System
System designed for rapid & safe separation of the crew from the launch vehicle in the event of a potentially catastrophic in-flight anomaly during ascent
Types of Launch Abort/Escape Systems
(slides 142-149)
Towers-Mercury, Apollo, Soyuz, Orion, Shenzhou
Pushers-Crew dragon, New Sheppard, Starliner
Ejection Seats-Gemini, Shuttle, X-15, Vostok, Buran
Personal Parachute - Shuttle, Spaceship 2
Launch Escape Modes
Pad abort - zero altitude/zero airspeed
Mode 1 - land close to the launch area
Mode 2 - rapid entry into atmosphere
Mode 3 - high altitude abort, thermal/entry velocity
Mode 4 - abort to orbit, one orbit then re-entry
Launch Escape Triggers
Guidance Navigation & Control - trajectory/vibe
Launch Vehicle - tank pressure, breakwire, computer
Manual - button push/ejection cord
Flight termination system - automated system
Spacecraft - independent escape mechanism
Launch Escape Scenarios
Premature or late booster thrust termination (rocket)
Rapid malfunctions which lead to catastrophic events
Slow deviations & malfunctions
Atmospheric Entry
Must provide controlled dissipation of kinetic and potential energy of the vehicle speed and altitude at each entry interface
Ballistic Entry
Simple to mechanize, little to no guidance, stable flight path angle and entry velocity needed
Reduces total energy input w/ high local heating
Gliding Entry
Assumes sufficient L/D to maintain a glide at a small flight path angle (like the shuttle)
Reduces instantaneous heating but increases total heat
Thermal Protection Systems
Heat sinking - body heat shield on suborbital flight
Ablative Shielding - Mercury, Apollo, Gemini (panels)
Radiative cooling - excellent insulation, Shuttle, heavy
Simple Impulse Orbital Maneuvers
Posigrade (in direction of motion) - raises orbit 180deg later
Retrograde (opposite motion) - lowers orbit 180deg later
Out of plane (toward Earth) - inclination change
Radially (thrusters) - rotates line of apsides
Single Impulse Orbit Maneuvers Ratios
Increasing v while r remains constant increases a
Decreasing v while r remains constant decreases a
Lambert Targeting
Find the transfer orbit that connects two position vectors
Relative Motion Plots (201-207)
Uses the target-centered rotating coordinate system expressed in Local Vertical Local Horizontal (LVLH)
Chaser increases velocity at perigee/slows at apogee
Human Spacecraft Subsystems
Propulsion
Structures
Avionics
Comm
GNC
Software
Power
ECLSS
Thermal
ECLSS
Environmental Control and Life Support System (ECLSS) maintains O2, H2O, Food, CO2, Waste, Heat levels to sustain crew
Atmospheric Gas Mix & Pressure (Earth)
21% oxygen (earth) & 78% nitrogen, pressure at 14.7psi or 101.3kPa or 760mmHg
What happens if ppO2 drops too low?
Increased respiratory rate
Numbness
Nausea
Fatigue
Headache
Dizziness
Hot or cold flashes
What happens if ppO2 and O2 concentrations are too high?
O2 toxicity - >3.1psi is toxic
Effect is driven by ppO2 not %O2
Physiological driven by ppO2
Flammability driven by %O2
Flammability - high %O2 concentration could lead to fires & should not exceed 30%
Spacecraft Decompression
Depressurization can occur due to penetration, valve failure, seal failure, collision, procedural error, slow leak, or rapid decompression
Rate of decompression causes pulmonary barotrauma, hypoxia, decompression sickness, and ebullism
Decompression Sickness (DCS)
Caused by inert nitrogen in the blood stream coming out of solution and resulting nitrogen bubbles cause pain and other symptoms. Prevented by 100% O2 pre-breathe.
Type 1 DCS– (less serious)
Limb or Joint Pain (bends), Skin manifestations such as itching and rash, Swelling or pain in lymph nodes
Type 2 DCS (serious)
headache, weakness, paralysis, dizziness, personality changes, loss of mental function), difficulty breathing, Death
Crew Module Atmospheric Pressure Trade
Sea-level pressure & %O2 - longer pre-breathe times prior to EVA, higher leak rates, higher power reqts
Use a reduced PB & increased %O2 - increased increase fire risk, increase oxygen toxicity, can increase hypoxia risk
Ventilation & Airflow
Insufficient ventilation can cause stagnant CO2 buildup
Provides a mean of cooling the cabin air & smoke detectors to monitor an entire enclosed area
Hypercapnia
CO2 concentration increase >23mmHg levels and results in not odorless/hard to realize impacts until it’s too late
Non-regenerable CO2 Removal
Lithium Hydroxide (LiOH) used to remove CO2 during short duration missions by flowing CO2 laden air through a single use container w/ LiOH granules
2kg of LiOH required per person per day
Regenerable CO2 Removal
Uses a regenerable system (machine) at the cost of additional power consumption & more complicated
Temperate & Humidity Control
Air temp is generally controlled by circulating air through gas/liquid heat exchanger
Humidity controlled by lowering the temp in the liquid cooling loop below the dew point to create a condensing heat exchanger (CHX)
Water, Food, & Waste Requirements
Hydration 2kg/day
Food rehydration ~0.5kg/day
Personal hygiene 0.4kg
Food requirements
Meet nutritional needs of the create safely & healthy, shelf-life, packaging & leftovers, meet daily energy reqts by WHO recommendation
Waste Collection (poop)
Suction system with collection, treatment, storage/disposal, including trash, poop, vomit, and food preparation waste
Space Suit Design
IVA (Intravehicular Activity) or Escape Suit
Connected to ship resources, worn inside spacecraft, not meant for pressurization, or used during emergency
EVA (extravehicular activity) requires a portable life support system and used during unpressurized environments; PLSS includes oxygen supply/pressure control, humidity control, thermal, carbon dioxide, etc
Crew Functions & Capabilities
Perception (visual, hearing, smell, vestibular, etc_
Cognition (problem solving, memory, decision making)
Action (command, piloting, do nothing)
Human Centered Design Process
Must consider human use from the start of the design process and create multi-stage/iterative problem solving processes, design assumptions, user evaluations, etv
Human Centered Design Process Flow Diagram
Define Requirement - conops, task analysis
Design - cockpit layout, display design
Implement - paper, wireframe, sim, mockups
Evaluate - user feedback, performance, usability
Re-start…
Function Allocation (Sully plane landing)
Decides whether a particular function will be accomplished by a person, technology, or some mix
Considers error rates, fatigue, costs, hazards, feasibility, etc
Function Allocation (Human vs. Machine)
Driven by skills, rules, knowledge, & expertise where expertise requires more human interaction vs. machine
Task Analysis (SpaceX spreadsheet example)
Study of what people & vehicle automation are require to do to achieve a specific goal - who does what & why
Display Design Principles
Legibility - contract, font, illumination, color
Top-down processing - consistent w/ mental models (on/off not off/on)
Redundancy - use dissimilar indications
Pictorial Realism - look like the real thing
Principle of moving part - move intuitive direction/pattern
Minimize info cost - keep frequently used in primary visual area
Replace memory - put info on display for quick reaction/readout
Consistency - use similar interfaces familiar by crewmember
Design of Spacecraft Controls
Flight controls - manual override of automated system
Physical switches - on/off subsystems
Display navigation - control to navigate between displays
Placement of Spacecraft Controls
Frequency of use
Task criticality
Located near corresponding displays
Vibe/Accel environments (above 3g operations)
Minimize Inadvertent Actuation
Switch guards, pins and lever locks
Placement (far)
Resistance (high actuation force)
Protective cover
Human Experimental Methods
Test use cases with actual humans/legibility
Deliberately change independent variable to effect dependent variables looking to test
Maintain control of the independent variable tests
Human Workload Parameters
Mental, physical, or both workload thresholds over a sustained period of time effects performance of tasks. High workload can lead to more errors, poor accuracy, frustration, and fatigue.
Reduce Workload Stress
Design controls, displays, & procedures to simplify
Limit use of working memory during high workload
Training
Frequent rests/breaks
Reduce workload as necessary by task
Usability
the extent to which a product can used by the specified users to achieve specified goals; user friendliness/ease of use
Learnability, Efficiency, Memorability, Errors, & Satisfaction
Situation Awareness
perception of elements in the environment within a volume of time and space
Poor situation awareness accounts for 31% accidents
Human error
when action is taken that was not intended by actor, not desired by rules or external observer
Inappropriate behavior that lowers system effectiveness
Anthropometry
Study and measurement of human body dimensions
Structural (static) dimensions
Functional (dynamic) dimensions
