BEST course Mission Analyses Rafael Wisniewski Aalborg University.

BEST course

Mission Analyses

Rafael Wisniewski

Aalborg University

Mission Analysis, BEST Course

Contents

• Introduction to the Course Short History to Spacecraft Engineering Environment and Orbits Spacecraft Configuration What orientation Elements of control Instrumentation Satellite Architecture Launchers Reduction of Mission Cost Mission Examples: Ørsted and Cubesat Exercises


Introduction

General plan for the course9-9.30 A short summary of the teamwork 9.30-12.15 New Lectures13-15.30 Team work on Given Excercises

Lectures1. Mission Analysis2. Spacecraft Engineering and Data Handling3. Space Environment and Orbit Modelling4. Power System5. Spacecraft Modelling 6. Communication system7. Spacecraft Autonomy8. Attitude Estimation and Sensors9. Course Evaluation


Short History #1

Sputnik-1 - USSR - (1957)First artificial satellite.

Explorer III - USA - (1958) Discovered Earth's radiation belt.

Pioneer 0 - USA Lunar Orbiter - (August 17, 1958) First stage exploded.

Pioneer 1 - USA Lunar Orbiter - (October 11, 1958) Failed to reach escape velocity.

Pioneer 3 - USA Lunar Flyby - (December 6, 1958) Failed to reach escape velocity.

Luna 1 - USSR Lunar Flyby - 361 kg - (January 2, 1959) Luna 1 was the first lunar flyby. It discovered the solar wind and is now in a solar orbit.

Pioneer 4 - USA Distant Lunar Flyby - 5.9 kg - (March 3, 1959) Space probe is now in a solar orbit.

Luna 2 - USSR Lunar Hard Lander - 387 kg - (September 12, 1959) Luna 2was the first spacecraft to impact the surface of the moon on September 14,

1959.


Short History #2

Vostok 1 USSR 1961, At the age of 27, Gagarin left the earth. It was April the 12th, 9.07 Moscow time (launch-site, Baikonur). 108 minutes later, he was back .

Luna 9 - Lunar Soft Lander - 1,580 kg - (January 31, 1966)

Luna 9 landed on the lunar surface

and retuned the first photographs

from the surface. Suerveyor 1- USA Lunar Soft Lander –

269 kg - (April 30, 1966 to 1967)

Surveyor 1 was the first American

soft landing on the lunar surface. Apollo 8 - USA Lunar Manned Orbiter - 28,883 kg - (December 21-27, 1968)

Crew: Frank Borman, James A. Lovell, Jr., William Anders. The crew undertook the first manned lunar fly-around and Earth return. The astronauts made 10 orbits of the moon.

Apollo 11 - USA Lunar Manned Lander - 43,811 kg - (July 16-24, 1969)

Crew: Neil A. Armstrong, Edwin E. Aldrin, Jr., Michael Collins. Apollo 11 was the first manned lunar landing, which took place on July 20, 1969. The landing site was Mare Tranquillitatis at latitude 0°67' N and longitude 23°49' E. Armstrong and Aldrin

collected 21.7 kilograms of soil and rock samples.

Mission Analysis, BEST CourseThe Earth –

Our Planet in the Solar System

The geomagnetic fieldan invisible shield

Sun is giant thermo-nuclear fusion.Its atmosphere: chromosphere, corona


Solar Activity


Solar Cycle


Overview of the Space Environment

External Factors Residual atmosphere (up to 800 km) - Drag causes orbit decay and

reentry Trapped protons - Degrades materials and electronic components,

causes single- event effects in semiconductor components. Trapped electrons - Degrades materials and electronic components Solar protons from flares - Degrades materials and electronic

components,causes single- event effects in semiconductor components.

Cosmic rays - causes single- event effects in semiconductor components. Solar radiation: IR, Visible, UV, X- Ray - Degrades materials Plasma from magnetic substorms - Causes spacecraft charging Atomic oxygen - Erodes exposed surfaces

Local Factors Outgassing (vaporization of surface atoms) – decomposition of materials.


Effects of South- Atlantic Anomaly

UoSAT- 3 Single- Event Upsets

Van Alen radiation belts

Mission Analysis, BEST CourseOrbits – definitions #1

semi-major axis is half the longest distance across the ellipseperiod is the time to make one orbitmean motion is the frequency (revs per day)apogee - highest altitudeperigee - lowest altitideeccentricity - orbit's deviation from a circle (shape)

Mission Analysis, BEST CourseOrbits definitions #2

Ascending node is the satellite's South to North equatorial crossingInclination is the orbital plane's tiltRight ascension of node is the angle from the Vernal equinox to the ascending nodeArgument of perigee is the angle between the acsending node and perigeeTrue anomaly - angle from perigee to the satellite

Mission Analysis, BEST CourseOrbits definitions #3

•The Earth rotation (0.465 km/s max.) is benificiary for prograde orbits•Launching eastward this velocity contributes not negligibly to the 7.9 km/s required for a LEO


Types of Orbits

Geostationary Earth Orbit (GEO) Low Earth Orbit (LEO)

Sun Synchronous Earth Synchronous

Highly Elliptical Orbits (HEO) Molniya

Nongeocentric Orbits Lunar Interplanetary


GEO at altitude of 35,786 km

Mission Analysis, BEST CourseOrbital Perturbations #1

Nodal regression used for Sun and Earth synchronous orbits


LEO orbit - Ørsted Orbit

Perigee/apogee: 620x850

Ascending node: 14:30 LT (drifting towards noon)

Inclination: 96.65 degree


Orbital Perturbations #2


Molniya

Molniya is russian kommunication orbit

Apogee: Ca. 40000 km

Perigee: Ca. 500 km

Inclination: 63.4°

Period: 11 timer 58 min. 02 sek.

The disadvantage is large dose of radiation from high energy protons and electrons


Spacecraft Subsystems

P a ylo a d(s )

O B C

S tru ctu re

AC S

Actu a to rs

S e n s o rs

E P SP C D U

B a tte ry

S o l a rPan e l (s )

COM

An te n n a

H arn e s s

Th e rm a lC on tro l

S e para .MES

• Structure and Mechanical System• Onboard Computer• Orbit and Attitude Control System• Power System• Onboard Communication• Command and Data Handling• Thermal Control• Ground Station• Payload


Attitude Control Subsystem

Torques

Controlactuator

On-boardcomputer

Groundcontrol

Attitudesensor

Attitude

Controller Actuator Spacecraft

Sensors

Commands

Attitude

Torques

Measuredattitude

Error signal


Attitude Control Subsystem (ACS)

Sensors Star tracker Rate sensors Magnetometer Sun sensors Earth horizon sensors

Actuators Momentum/Reaction wheels Magnetorquer coils/rods Thruster Libration Damper Permanent magnet


Attitude Control

Mission Analysis, BEST CourseSolar efficiency


Solar Efficiency


Operational Phases

Launch Initial acquisition

Deployment of

appandages

Attitudestabilization

Scienceobservation

CommissioningScience

calibration

Contingencyoperations


What is Mission Analysis ?

”Mission analysis is a structured method of ensuring that the mission success criteria's are clear and well understood.”

& ”Mission analysis ensures, that the mission

fulfils the overall success criteria's and at the same time stays within the project boundary conditions technical, political and financial.”

& ”Mission analysis define the onboard

subsystems configuration and basic subsystem requirements.”


Mission Analysis


Mad Circle


Initial Considerations – Mission Requirements and Constraints

During the FIRST steps of the space systems engineering process we define mission requirements and constraints:

State the mission objective – why we do the mission

Identify mission users – who will benefit from or use the information produced by the mission

Create the operations concept – how will all the mission elements fit together

Identify mission constraints (Cost, schedule and performance)

Mission Analysis, BEST CourseInitial Considerations – System

Requirements

During the SECOND step of the space systems engineering process we derive the system requirements

Review the constraints on mission architecture (Launch vehicle, orbit, operations, lifetime etc.)

Identify and characterize the mission subject – (eg. ”what” will the spacecraft instrument complex (payload) do ?)

Derive payload requirements Derive orbital requirements Determine basic spacecraft size and mass (envelope) Identify potential launch vehicles Derive operations network requirements

(Groundstations).

Mission Analysis, BEST CourseInitial Considerations - Subsystem

definition

During the THIRD step of the space systems engineering process we start defining the subsystems, and after a few iterations of the requirements etc, the design can begin.

1. Define ACS concepts (based on pointing, positioning and stability requirements)

2. Define reduncdancy concepts.3. Define onboard subsystems (EPS, COM, CDH, Payload

computer, On board SW, ACS etc.4. Perform data flow analysis5. Determine ground coverage and communications concept link

budget6. Determine needed power and power output analysis7. Define thermal requirements and perform initial analysis8. Determine structural requirements and perform initial analysis9. Analyse radiation environment10. RE- ITERATE ALL


Mission Analysis in the Loop

BEST course Mission Analyses Rafael Wisniewski Aalborg University.

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Transcript of BEST course Mission Analyses Rafael Wisniewski Aalborg University.