Explain the 3 imperatives for human spaceflight exploration.
Unify (political): Moving towards a global mission
Explore(cultural): Expanding human experience
Understand(scientific): Gaining knowledges and insights
For each fundamental human question
Where did we come from?
What will happen to us in the future?
Are we alone in the universe?
provide an example of a potential destination for human spaceflight exploration and how it could help answering it.
Determine how the universe of galaxies, stars and planets began and evolved——-Observe and understand the planetary formation process in the galaxy——WITH telescopes at SEL2
Determine the potential for establishing permanent human presence in space———Determine feasibility of in-situ resource production——ON Mars
Determine if there is or ever has been extra-terrestrial life in the solar system———Search for past and current life——ON Mars or Europa
Advantages/Disadvantages of human spaceflight vs robotic.
Human Spaceflight:
Pros: 1. Exploring the unexpected.
2. Real-time operations and decisions.
3. Recognize the correlation.
4. Possibility of repairing and modifying
cons: 1. LSS needed 2. Special training needed 3. Safety risks
Robotic:
pros: 1. Automated system 2. Operated in harsh conditions without LSS 3. Reach regions where human can’t
cons: 1. Maintainence 2. Data transfer problem 3. Limited scientific knowledge
Explain what has been done so far in human spaceflight.(Name past missions and space stations)
Missions:
Vostok 1, Freedom 7, Voskhod 2, Apollo 8, Apollo 11, Apollo 17
Space stations:
Salyut 1, Skylab, Salyut 7, Spacelab, MIR
Explain what current stauts of human spaceflight is (current stations and private missions).
ISS 2. Tiangong 3. Commercial Flights 4. Artemis
Explain current plans for human spaceflights (from ISECG Artemis, Gateway)
ISECG shows the future plans for going to lunar surface in 2 phases. 1 phase is sending up the lunar space station Gateway and followed with Artemis Missions II and III of crewed test flight orbiting moon and landing on the moon. 2 phase is to build habitation on lunar surface for futher research of moon and prepare for going to mars.
Explain why Mission Analysis is important for human spaceflight missions.
The purposes of human spaceflight mission analysis is to provide an end-to-end model of a human spaceflight mission concept and perform trade studies with regard to key mission drivers.
Explain the human mission conceptual design process.
Solution-neutral input defining mission destination and objectives
Reference design for key mission elements
Trade space analysis
Explain what NEOs are and provide examples for possible mission objectives
NEOs: Asteroids and Comets that are near or cross the Earth’s orbit
Possible Mission Objectives:
•Perform physical and chemical characterization of the NEO •Return 100 kg or more of samples from diverse sites on the NEO
•Gain experience operating in interplanetary space at significant distances from Earth
•Utilize commercial assets if possible
Explain and discuss how crew size, trajectories and payload influence the conceptual reference design.
Crew size: The number of astronauts onboard directly affects the habitation consideration, safety estimation and life support system.
Trajectories: The chosen flight path determines mission duration, deep space propulsion needs, and structural design.
Mission Payload:
Payload calculations must account for fuel needs, particularly for deep space missions requiring multiple burns.
Long-duration missions demand additional payload for habitat modules.
Explain the difference between bottom-up design and top-down design and how they are used for modelling the basic crew compartment and habitat.
•Bottom-up detailed design based on physical principles and machine elements
Bottom-up model needs subsystem models and associated simulations
•Top-down design based on analogies and scaling
Top-down models for crew compartments and habitats is based on linear scaling of equiment mass with crew and linear scaling of consumables mass with crew and mission duration
Explain the need for trade-off analyses.
It is needed for balancing mass and performance and evaluating different design options to achieve the best possible outcome.
Briefly explain the advantage of Hohmann transfer trajectories and exceptions to their use
Hohmann transfer trajectories are the most fuel-efficient way to move between two circular orbits around the same central body.
Limitations:
Long time travel: when maybe flyby is more efficient.
Highly elliptical orbit
Explain what the Patched Conics Method is and what it is used for.
The Patched Conics method allows for a simplified calculation of trajectories based on the assumption that the spacecraft is at any given time under the influence of only one central body.
The patched conics method provides a way to calculate mission Δvs and transfer / stay times with relatively little effort
Explain what the Mission Mode is and what it is used for.
The Mission Mode is a description of the basic mission architecture, i.e. a mapping of mission functions to mission elements of form.
Why do we need the Electrical Power System?
Powering onboard systems
Environmental control and Life support system
Propulsion and Navigation
Thermal control system
Altitude and Orbit control system
What are the available energy sources in space?
Solar energy
Nuclear energy
Chemical energy
How is electrical energy generated?
Using solar arrays to convert solar energy into electrical energy
Using Radioisotope Thermoelectric Generator to convert heat into electrical energy
Using battery
How is electrical energy stored?
Stored in the battery
using reversible fuel cell
Flywheel
How is electrical energy conditioned, regulated and distributed?
Control: Using dielectric material to build ISS structure.
Using PCU
Regulation: 1. Regulate the power output from solar panels and energy storage system using DCSU
2.Regulate the voltages during changing of energy storage syste using BCDU
Distribution: Solar panels 160V DC
Secondary distribution 120V DC
What are the design drivers for the EPS?
Eclipse time
Thermal budget
Assembly
Safety
Reliability and operational life
Describe the EPS of the ISS.
Define the meaning of weightlessness.
A state of a body that occurs when the forces acting at any point on the body cancel each other out in terms of size and direction.
Explain if humans are weightless when flying to the moon.
Yes because the only force that acts on human is gravity, whether from earth or from moon. The gravity still exists.
Name the experimental platforms for conducting experiments under microgravity and explain the differences.
Drop tower, parabola flight
Texus Sounding rocket
Sketch how gravity changes during a parabola flight.
Explain and identify how the space environment influences a space station.
Space environment of radiation, microgravity and residual atmosphere can affect research in fundamental physics, human physiology, biology and material science.
Identify DC and AC microgravity contributions in LEO.
DC: 1. Solar radiation pressure
2.Atmospheric drag
3.Tidal forces
AC: 1.Altitude Control 2. g-Jitter
Explain what tidal forces and g-jitter are and how they affect a space station/space craft.
Tidal forces: Tidal forces are the dominating residual DC accelerations and of the order µg.
Creates different levels of ug on different area of ISS.
g-Jitter: Resonance response of the ISS to internal and external interference in the frequency range 0.1 – 100 Hz
have impacts on experiments regarding fluid dynamics or crystal growth.
Sketch the coordination system of the ISS and indicate the flight direction.
Explain how liquids behave in microgravity.
There is no convection in liquid
Sentimentation evenly distributed in liquid
Liquid form spherical droplets.
Liquid stick between two surfaces forming a liquid column because of adhesion.
Explain why science is conducted in space and provide examples on scientific disciplines that have been studied in space.
Scientific experiments in weightlessness are usually done to study effects that are masked by gravitational forces on earth.
lighting candle in ug:study on flames behavior and fuel mixtures on space station may lead to improved fuel efficiency and reduced pollution on earth.
Cold atom laboratory: to study the wave nature of atoms.
Astrophysics: measures particles in cosmic rays helps us understand the formation of universe.
Protein Crystal Growth
Material Testing
Explain the main difference between a candle burning on Earth and a candle burning in microgravity.
The candle burns on earth react with H first to create high energy and leads to convection. Soot particles were burnt in upper flame.
The candle burns in space station is fully diffusion, which the C and H burn completely at the same time.
Provide an example for a space spin off.
Robotics development
Space mouse
Cordless screwdriver
Cerami brake disk
Give examples for launch sites and space transportation vehicles to the ISS.
Baikonur -Soyuz
Cape Canaveral- Dragon crew- falcon 9
Describe how the ISS is structured and for what it is used.
Describe why sport exercises on the ISS are necessary and how sport is done on the ISS.
To avoid losing muscles and maintain bone density.
The astronaut need to be tied to the treadmill and weight lifting by using vacuum cylinder to apply resistance.
Explain how an emergency/alarm is handled on the ISS.
Stop and identify the emergency Mission control center on earth confirms the situation and provide instructions.
If there is fire take the portable fire extinguisher
Depressurization:putting on mask first -locate the source of leak with pressure sensor
Describe how Earth can be seen from the ISS.
The earth surface can be seen directly from cupola, and 16 sunrise and sunset coming from horizon.
Describe how return from the ISS to Earth is realized.
Undocking from ISS with Crew Dragon
Deorbit burn
Atmospheric reentry
Parachute deployment
Splashdown in ocean
Explain which characteristics need to be considered for space communications and why
Large distance -how to make comms works
Vacuum- what kind of wave can get through
No massive interferences- could be damaged because of it
Radiation-Atenna need to avoid the sun
Thermal / Power issues- large range of temperature in space
No easy fix/replacement possible
Name examples for orbits and explain the differences.
Low Earth Orbit(LEO)- Satellites move fast and complete ~16 orbits per day.
MEO higher than LEO used for GPS
GEO- Satellites appear stationary from Earth because they orbit at the same speed as Earth's rotation. For TV, weather forecasting
Explain how the atmosphere influence the frequency.
The atmosphere may attenuate the frequency because of absorption. with higher frequencies the atmospheric attenuation increases.
Explain main aspects of astronaut comms.
Voice(communications with mission control center)
Video(for payload and experiments)
Telemetry
Explain characteristics of space comms in human spaceflight.
Signal visibilities: eclipse time
Time: GPS time
CAPCOM / EUROCOM: communication is specific set between control center and S/C
Privacy
Name the underlying physical equations for space communication
Maxwell equations
Explain what a radio wave is and how electromagnetic waves behave in free space.
A radio wave is an electromagnetic radiation generated by time varying electrical currents and travelling at the speed of the light.
In free space, all electromagnetic waves (radio, light, X-rays, etc.) obey the inverse-square law.
Explain the different polarization types (linear, circular, elliptical)
Linear: the electric field vector is contained in a plane along the direction of propagation
Circular (right or left): the electric field has a constant magnitude but its direction rotates with time at a steady rate in a plane perpendicular to the direction of the wave
Elliptical: the electric field vector describes an ellipse in a plane perpendicular to the direction of the wave
Explain what an antenna is and the advantage of parabolic antennas.
An antenna is the interface between radio waves propagating through space and electric currents moving in metal conductors.
Advantage: High directivity
Explain what is meant by antenna directivity and beamwidth.
Directivity refers to how focused or concentrated the antenna’s radiation is in a particular direction.
Beamwidth refers to the angular width of the antenna’s radiation pattern.
Explain how the directivity correlates with the diameter of the antenna and the frequency.
Higher diameter higher D
Higher frequency higher D
Name and explain the important parameters of an antenna.
Gain: How well the antenna converts input power into radio waves
Noise Temperature: Noise produced from different sources
G/T: figure of merit of antenna performance
EIRP: the total power that would have to be radiated by an isotropic atenna to get the same sigal strength as atenna’s strongest beam.
Explain what modulation is and sketch the difference between the three basic modulation types.
Modulation is a process of varying one or more properties of a periodic waveform, with a modulating signal that typically contains information to be transmitted.
Amplitude
Frequency
Phase
Explain what the frequency spectrum is.
The frequency spectrum is a representation of a signal's power or amplitude as a function of frequency. It shows how the signal's energy is distributed across different frequency components.
Explain what QPSK, BPSK are and what is meant by BER. What modulations are preferred for reliable/not reliable channels?
BER is defined as the ratio of the number of wrong bits over the number of total bits.
In reliable channels →high order modulations are preferred due to higher efficiency
In not reliable channels →low order modulations are preferred to limit the BER
Explain the meaning of the Eb/N0.
Eb/N0 stands for the Energy per Bit to Noise Power Spectral Density Ratio. It's a measure of the signal quality relative to the noise in the system.
Describe the thermal environment of a spacecraft.
The thermal environment needs to be favorable to residence of humans and to the operations of spacecraft equipments.
State mean values of environmental heat sources in low earth orbit.
M_sun= 1371 W/m^2
M_E= 237 W/m^2
Why is TCS needed?
Existing temperature margins for spacecraft hardware in operating and non operating modes
Restricted heat rejection only by radiation
Nonsteady-state external heat
Difference in time and location for generated and needed heat or cooling accumulation and demands
How is TCS constructed?
• Employ passive thermal control techniques (thermal conduction & radiation, heat capacity)
• Improve or decrease local heat transfer (heat resistance)
• Selection of internal and outer surfaces α/ε (thermal absorption / emission)
• Use active heat transfer for high heat loads
State the objectives of a spacecraft thermal control system.
Existing temperature margins for S/C hardware in operating and non operating modes
Nonsteady-state external heat loads for several mission scenarios
Describe the heat transfer mechanisms in general
Conduction: Energy is transfered by direct contact
Convection: Energy is transfered by the mass motion of molecules
Radiation: Energy is transfered by electromagnetic radiation
Give the heat balance equation for a structure in low earth orbit
Describe the thermal analysis approach for spacecraft.
decide integration depth, integrated system with centeal heat transport system and central heat rejection or autonomus system
Topology and dimensions: extensive systems or compact systems
Heat transport system: performance, maturity and maintainance
Thermal environment definition range for different utilization
Main tasks and users of TCS
Know examples for active and passive thermal control components
ATCS: 1. Radiators 2. Single phase fluid loop 3. Heat pipe
PTCS: 1. Thermal Insulation 2. Thermal protect system 3. Surface finishing
Name the first US human spaceflight program.
Programm Mercury
Explain briefly the reason for the chosen amount of crewmembers for Mercury and Gemini.
Mercury: 1 Crew because it is designed to test basic flight capabilities.
Gemini : 2 crews for more complex tasks preparing for Apollo's Moon missions.
Name and explain the Apollo System elements.
Command and Service Module: Earth launch and entry, in-space maneuvers and habitation
Launch Escape System: separation of Apollo capsule in case of launch abort
Saturn IB launch vehicle:used for LEO missions
Saturn V launch vehicle:used for lunar missions1& Skylab
Lunar module(LM): lunar landing, lunar surface habitation
Explain what the STS is and its components.
Space Transportation System
Components:
Shuttle Orbiter(3 main engines and 2 OMS pods, Payload bay and crew cabin)
External Tank
2 reusable solid rocket booster
Explain which positions you have in a 4-person crewed mission and why and how they are seated in a crew vehicle.
All 4 crews sit in flight deck, Pilot and commander in front and 2 Mission specialists in back to check on pilot and commander.
Name and explain the components of the Orion spacecraft.
Launch abort system: in case of emergency to pull crew module away from the rocket
Service module: for storing the propulsion
Crew module: for habitation
Provide examples for crew vehicles (in use & planned).
In use: Orion, Crew Dragon, starliner
Planned: Dream chaser
Explain briefly how you could distinguish a crewed vehicle from a cargo vehicle.
From the launch abort tower.
Explain what DAEZ stand for.
Downrange Abort Exclusion Zone.
It is the exclusion zone for Crew Dragon to abort because it is too far away from both sides of coast.
Explain what the Soyuz is.
The Soyuz is Russia's human spacecraft, developed during Soviet times and incrementally modernized
Explain the main difference between the soyuz and the progress.
Soyuz: Crewed spacecraft
Progress: Cargo spacecraft
Explain what the Chinese Shenzhou system is and on which spacecraft it is based.
Crewed spacecreft based on Soyuz
Explain the terms LoM and LoC.
LoM:Loss of mission
LoC: Loss of crew
Explain what human rating is and how it can be achieved.
Human-rating is a process of reducing probabilities of Loss of Crew (LoC) and Loss of Mission (LoM) of a space system to acceptable levels.
Human-rating is achieved by providing redundancy in key subsystems like launch abort system.
Features such as self-helping mechanisms or passive cooling can be employed.
Trajectories designed to include features such as "free-return"
Explain why you need AOCS.
Orbit control:
Achieve designated lifetime
Allow rendezvous manoeuvre
Maintain safe on-board operations
Allow microgravity experiments
Collision Avoidance
Attitude control:
Maintain solar-electric power generation
Allow safe docking operations
Maintain communication to Earth
Explain the Keplerian elements.
Semimajor-axis a
Eccentricity e
Position-True Anomaly theta
Inclination i
RAAN (Right Ascension of Ascending Node) omega
Argument of perigee w
Explain the difference between Orbit and Attitude.
Orbit is defined by the shape orientation.
Attitude is defined by the orientation of the body fixed coordinate system w.r.t. a reference system
Explain and discuss perturbations in LEO.
LEO perturbations: Aerodyn. Drag, Aerodyn. torque, gravity gradient torque(design driving parameter)
solar pressure, earth oblateness,
Explain and outline the influence of aerodynamic drag on a space station. Which parameters are most important?
Orbit decay:continously lower itself
perturbation torque:unintended rotation
Atmospheric density.
Explain and discuss influences on the atmospheric density.
The more active the solar activity, the higher the density.
Discuss the relation of orbit decay and reboost.
Orbit decay continuously lowers altitude → Reboost counteracts it by restoring the desired orbit.
Name the definitions of POP, IOP, ASL, PSL, LH, LV.
POP: Perpendicular to Orbit Plane
IOP: In Orbit Plane
ASL: Aligned with Sun Line
PSL: Perpendicular to Sun Line
LH: Local Horizon
LV: Local Vertical
Explain the different flight modes and discuss the selection criteria.
Earth Oriented Flight Mode
Inertial Flight Mode
Criteria:
Mission & Utilization requirements
Gravity Gradient Attitude Stability
Minimum Drag
Mechanical Effort for solar tracking
Explain the reason for aerodynamic torque.
Centre of pressure of a space station often has offset ⊥ v to centre of mass, which create torque.
Explain what the gravity gradient torque is.
Explain what actuators are used on the ISS for compensation of perturbations.
Perturbation: CMG Desaturation
Aerodyn. Drag: use Thruster to reboost
Name influences on the AOCS.
Contamination due to thruster operation
Safety of components and operation
Redundancies to guarantee operation in case of failures
Servicing/Maintenance
How to design the AOCS?
Definition of flight mode and configuration
rough calculation of orbit decay
choose orbital control strategy(permanent or impulsive)
check attitude performance and choose attitude control system
calculate required propellant
Identify the human metabolic needs for survival
Food, portable water, hygiene water
Identify the human physiological needs for survival
Atmospheric composition
Pressure
Temperature
Relative humidity
Explain the main tasks of an ECLSS system
Atmosphere management
Water management
Food management
Waste management
Describe how ECLSS systems can be classified
By degree of closure and types of process.
Open, partialy closed and closed
Physico-chemical, hybrid and biological
Identify the best ECLSS approach for a specific mission duration.
According to the linear relationship between mission duration and environmental system mass under different classification, when it comes to a break even point it means to choose another system type
Explain how technologies for air management work.
CO2 removal:
Using LiOH Cartridges for chemical reaction to remove CO2
4BMS
SAWD
Sabatier Reactor
O2 genertation
Water electrolysis
Explain how technologies for water management work
Multifiltration
Vapour Compression Distillation (VCD)
Explain how food could be produced for long-duration missions.
farming
higher plants algae
Name influences on a space architecture.
Utilization
Radiation
ug
Volume restriction
Power provision
Provide a definition of a system.
A set of different elements so connected or related as to perform a unique function not performable by the elements alone.
Provide a definition of Systems Engineering.
An interdisciplinary collaborative approach to derive, evolve, and verify a life cycle balanced system solution that satisfies customers expectations and meets public acceptability
Explain and outline the difference between sequential vs. concurrent engineering
Explain and discuss the importance and use of conceptual design.
Most important decisions are made, driving mission performance, cost, schedule, risk, etc.
Mission and system elements are strongly interdependent
crucial for a permission of a project
Determine mission and system requirement
Explain the methodological approach of conceptual design.
top-dowm
Explain and discuss the methodology and elements/steps of conceptual design.
Define Objectives
Characterize the system
Evaluate the system
Define Requirements
Explain the difference between a pressurized module backbone and truss backbone.
Pressurized module backbone: uses pressurized modules as the primary structural connection between different sections of a spacecraft or space station.
Truss backbone: Uses an external, unpressurized truss structure to support pressurized modules and other equipment
Provide examples of criteria to select an orbit and to select the flight mode.
Orbit:
Orbital access to target or transfer vehicles
Communication Performance
Earth Observation Performance
Drag
Flight mode:
mission needs
rendezvous and docking
minimizing drag
effects of gravity gadient
Outline critical subsystems of a space station in conceptual design.
EPS
ECLSS
AOCS
TCS
Explain how configurations are developed within conceptual design.
Determine components
Size components:dimensions, mass, kinematics
Develop Topology: Arrangement of components
Discuss potential configuration design conflicts.
-Microgravity level vs Aerodynamic drag (Aerodynamic drag needs reboost which disrupts the micro-g experiments)
-Attitude Stability and Control (frequent adjustment may create vibration which are not stable)
-Energy Provision vs Thermal Control (Space arrangement)
Explain the meaning of risk and safety.
Risk: damage extent x probability
Safety: Freedom from conditions that can cause death, injury, occupational illness, damage to or loss of equipment or property, or damage to the environment
Give one risk example associated with spacesuits.
STS 118 EVA abort after punctuation
What needs consideration when designing spacesuits for future human spaceflight missions in terms of safety and risk?
Protection Against Environmental Hazards
Suit Longevity and Maintainability
Why do we need to do risk assessment and which fields need to be addressed?
(0) Legal
(1) feasibility evaluation
(2) comparing competing designs
(3) identification of potential reliability problems
(4) to provide reliability input to other tasks , subsystems and designs
Fields:
Load studies and requirements specification
Functional (Failure) analysis & testing
Human Factors / Errors / Training & Certification
Documentation & spare parts
Give examples for standards that can be used for the design of spacesuits.
ECSS
NASA STD-3001
Describe and give examples for how spacesuits can be tested on ground.
By doing simple tasks to test the mobility and dextertity.
Cryotest for testing the ability of spacesuit to survive in extreme environment.
Insulating test
Describe the procedural sequence for how an astronaut needs to operate.
Planning input: Experiment design & needs
Mission plan: what to do when
Standard operating procedures: Who is responsible
Experiment procedures: how to do
Provide an overview of the safety process.
SSPP(system safety program plan)
PHL(Potential Hazards Lists)
PHA(Process Hazard Analysis)
SAR(Safety Assessment Report)
Give examples for common cause of failures.
Incorrect practises are applied
performed by incorrect people
within the organisation at an incorrect time of the system life cycle.
What kind of “angles of attack” are there?
Mechanical
user error
chemical, laser
electrical
Operation storage maintainance
Explain the difference between h/w and s/w risks and provide examples for s/w failures.
h/w: random faults
s/w: systematic faults
-ariane 5 explosion: because of a bug in inertial reference system led to an unhandled exception when converting a 64-bit floating point number to a 16-bit integer.
What happened during the EVA23 accident in 2013?
Water beagn leaking into Luca’s helmet during EVA walk. And he reported difficulty in hearing and breathing. stuggled to find his way back to airlock.
Explain what Pareto Frontier is.
The Pareto Frontier is a idealized relationship between performance and cost.
In which project phases is cost estimating important?
Phase B
Explain and discuss the three main cost estimating techniques and their differences.
-Analogy: apply relative scaling to a historical data point
-Engineering build up(Bottom-up): Use drwaings and bill of material for detailed estimating
-Parametric(Top-down): Use mathematical relationships to describe products
Explain the two different kinds of parametric cost models and their differences.
Specific Cost Model: only products which belongs to the same product family
General Cost Model: reusable model that applies to multiple systems or industries based on MX
Why do you need a product breakdown structure for estimating the costs?
Helps to identify relevant costs and to verify an estimate’s completeness
Permits consistent comparisons between alterative architectures and system designs
Provides a logical link among segments of a program or project
Explain what the AMCM is and for what it can be used.
The Advanced Missions Cost Model (AMCM) is a simple model that provides a useful method for quick turnaround, rough‐order‐of magnitude estimating.
Used for estimating the development and productioncost of spacecraft, space transportation systems, and space infrastructure.
Provide examples on external factors and explain how they influence cost estimation
Country of origin
Inflation factors
Learning effects
Funding profiles
Explain the difference between the Boeing/Crawford and the Wright learning curves.
Wright: Describes how unit production cost decreases as total production doubles.
Boeing/Crawford: assumes a slower initial learning phase and better long-term efficiency.
Explain what is meant by risk, reward and uncertainty
Risk: A potential, future negative impact, or consequence
Uncertainty: Uncertainty leads to risk
Reward: The probability that the estimate will be sufficient is the Reward
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