ARMADA Applying Reliable Methods to Analyse and Deflect an Asteroid M.F. van Amerongen A. Hutan J. Anckaert T.A.J. Meslin P.M. van den Berg U.B. Mukhtar J.M. Fisser A.S. Parkash J.M. Heywood J. Ramos de la Rosa Final Review Design Synthesis Excercise Aerospace Engineering June 29, 2016 (This page is intentionally left blank.) Mission to a Small Near-Earth Object Final Review Version 1.0 Delft University of Technology Faculty of Aerospace Engineering June 29, 2016 by Group 03 M.F. van Amerongen 4295196 J. Anckaert 4304411 P.M. van den Berg 4207696 J.M. Fisser 4290089 J.M. Heywood 4219554 A. Hutan 4195744 T.A.J. Meslin 4220269 U.B. Mukhtar 4206363 A.S. Parkash 4278356 J. Ramos de la Rosa 4228596 Supervisors: Dr.ir. E.J.O. Schrama Astrodynamics and Space Missions Dr. A. Menicucci Space Systems Engineering J.S. Bahamonde MSc. Flight Performance and Propulsion Lists of abbreviations ADCS Attitude Determination and Control System APL Applied Physics Laboratory (of the Johns Hopkins University) APM Antenna pointing mechanism ARMADA Applying Reliable Methods to Analyse and Deflect an Asteroid (mission name) AU Astronomical unit BER Bit error rate BPSK Bipolar phase-shift keying C&DH Command and data handling CNR Carrier-to-noise ratio CPU Central processing unit DSE Design Synthesis Exercise DSN Deep Space Network DST Deep space transponder EIRP Effective isotropic radiated power ESA European Space Agency FEEP Field-emission electric propulsion HPBW Half-power beam width HRM Hold-down and release mechanism IR Infrared JPL Jet Propulsion Laboratory MMH Monomethylhydrazine NASA National Aeronautics and Space Administration NEAR Near Earth Asteroid Rendezvous (NASA/APL mission) NEO Near Earth object O/F Oxidizer fuel ratio OBC On-board computer OQPSK Offset quadrature phase-shift keying QPSK Quadrature phase-shift keying RPA Rocket Propulsion Analysis v1.2 lite edition RTG Radioisotope Thermoelectric Generator SNR Signal-to-noise ratio SSPA Solid state power amplifier TT&C Telemetry, tracking & command TWTA Travelling wave tube amplifier Capture a Small Asteroid and Change Its Orbit iii Delft University of Technology Nomenclature a Semi-major axis km Pcharge Battery charging power W 2 As Enlightened surface area m Preq Power required W B Bandwidth Hz Pttc Power required for TT&C W C Carrier power W Pion Ion thruster power W −1 c Speed of light m s P Surface reflectance - −1 Cch Channel capacity s r Radius km Creq Capacity required J Ri Spacecraft-object(i) distance m d Distance m rast Radius of Apophis m D Battery capacity degradation coeffi- cap S Solar constant at 1AU W m−2 cient - 0 2 Sin Solar input flux W m Dcell PV cell degradation coefficient - T Temperature K Dinher Inherent degradation coefficient - T Torque N m DCttc Duty cycle of TT&C - E Eccentric anomaly rad t Time s e Eccentricity - Tcycle Operational cycle duration s Ecell PV cell efficiency - Tredun Redundancy time duration s Edc Battery discharge efficiency - Treq Thrust required (for Ion thrusters) N −1 c Frequency s tdump Momentum dumping time s F Force N tp Deflection time s Fg Gravity force N V Absolute Velocity km s−1 Fpath Path loss factor - v Velocity component km s−1 Fpow Power factor for power system - −1 Ve;ion Ion thruster exhaust velocity m s Frel Reliability margin factor - αexh Thruster exhaust plume angle ° G Standard gravitational parameter α Thruster misalignment angle m3s−2 mis ° αT Thruster angle ° g0 Sea level gravitational acceleration on Earth m s−2 γ Flight path angle rad 2 −1 h Angular momentum km s ∆c Distance center of mass and pressure m i Inclination angle rad ∆X Deflection distance m Isp Specific impulse s ηion Ion thruster efficiency - L Thruster moment arm m θ Angle local vertical and z-axis rad L Limit on depth of discharge - DoD θ True anomaly rad M Mean anomaly rad θ Pitch angle rad M Mass of Apophis kg ast ¨ −2 θslew Slew acceleration rad s mavg Average spacecraft mass kg θslew Slew angle rad MF Margin factor - −1 λ Wavelength m m_ ion Ion thruster mass flow rate kg s µ Gravitational parameter m3 s−2 Mprop Propellant mass kg φ Solar incidence angle rad N Noise power W ' Roll angle rad n Mean motion rad s−1 Yaw angle rad ntr Number of thrusters - P Orbital period s Ω Right ascension of ascending node rad P Power W ! Argument of periapsis rad Capture a Small Asteroid and Change Its Orbit iv Delft University of Technology List of Figures 2.1 Mission timeline . .2 2.2 Functional flow block diagram . .3 2.3 Functional breakdown structure . .4 3.1 The Kepler orbital elements in two dimensions, showing r, θ, a, b, e, and E ...5 3.2 Lambert's problem, describing the path from one point to another in a set time [1]7 3.3 A schematic overview of the MATLAB model . 10 3.4 Overview of the manoeuvres at departure and arrival . 10 3.5 The three-dimensional model plot. The orbit colors are blue for Earth, orange for Venus, magenta for Apophis, and green for the transfer orbit when departing at 21st of April 2021 and travel for 245 days. The diamonds indicate starting positions, except for the green diamond which indicates arrival position. 11 3.6 The model plot from a side-view to show the inclination, the view is towards the vernal equinox, so the bodies progress counterclockwise. Axes are not in the same scale for clarity. 11 3.7 Porkchop contour plot showing the total ∆V for a range of departure dates and travel times, with reference date January 1st, 2021. 12 3.8 Porkchop contour plot showing the arrival velocity for a range of departure dates and travel times, with reference date January 1st, 2021 . 12 4.1 Schematic interpretation of gravity tractor concept. 13 4.2 Interpretation of thruster plume effect . 13 4.3 Spacecraft mass vs. deflection time . 14 4.4 Spacecraft mass vs. deflection time for seven hovering distances . 14 4.5 A schematic overview of Earth's and Apophis' orbits . 16 4.6 Computation of velocity components of Apophis (km/s) . 16 5.1 X-ray emission by incident radiation [2] . 20 5.2 Alignment accuracy and alignment knowledge . 22 5.3 Polarimetry . 23 6.1 Block diagram of the propulsion system sizing MATLAB tool . 30 6.2 Spacecraft mass and ion thruster power as a function of time in the case of a nominal deflection . 33 6.3 Spacecraft mass and ion thruster power as a function of time in the worst case deflection scenario . 33 6.4 Thrust required during deflection (nominal case) . 33 6.5 Thrust required during deflection (worst case) . 33 6.6 Deflection distance as function of time (nominal case) . 33 6.7 Deflection distance as function of time (worst case) . 33 6.8 The Aerojet R42 engine used for orbit insertion [3] . 34 6.9 The EADS Astrium 10N Bi-propellant engines for orbit keeping and ADCS [4] . 34 6.10 The Qinetiq T5 ion thruster [5] . 34 6.11 Feed system diagram for the chemical propulsion system . 35 7.1 Tetrahedral reaction wheel configuration [6] . 41 7.2 System response with and without wheel dynamics . 46 7.3 Slew manoeuvre simulation . 47 7.4 Closed-loop response to a continuous disturbance torque . 47 8.1 C&DH process from received commands to commands' outputs . 48 8.2 Command and data handling communication flow diagram . 49 8.3 Sensors communication flow . 50 8.4 Thermal communication flow . 50 8.5 Mechanisms communication flow . 50 8.6 Propulsion & navigation communication flow . 50 8.7 ADCS communication flow . 51 8.8 Communication flow . 51 8.9 Power communication flow . 51 8.10 Control block . 51 8.11 Data Handling block diagram . 56 9.1 Probability of an error for different values of z, which is a function of the SNR. The selected value for the BER is marked. 61 Capture a Small Asteroid and Change Its Orbit v Delft University of Technology 9.2 Layout of the communications subsystem . 63 9.3 On the left the main antenna gain, on the right figure, the gain of both a helix and horn antenna for each diameter . 64 9.4 Primary and secondary antenna's mass . 65 9.5 Horn size parameters . 65 9.6 On the left, primary antenna's HPBW for different diameter values, and on the right, secondary antenna's HPBW for varying diameter . 65 10.1 Spacecraft conductive and radiative paths . 69 10.2 External spacecraft temperatures without passive control . 71 10.3 Spacecraft component temperatures without passive control . 71 10.4 Spacecraft component temperatures after passive control . 71 10.5 Aerothermal flux after fairing jettisoning . 72 10.6 Internal thermal response under aerothermal flux . 72 10.7 Power determination scheme . 73 10.8 Thermal response at perihelion with sensor side sun facing . 73 10.9 Thermal response at perihelion after active cooling implementation . 73 10.10Thermal response in eclipse . 73 10.11Thermal response in eclipse with active thermal control . 73 11.1 Power system energy source selection [7] . 77 11.2 Electrical block diagram fully regulated power system [7] . 78 11.3 Bus voltage selection [7] . 78 11.4 Flight path angle (γ)[1]................................ 80 11.5 The effective solar flux as a function of true anomaly . 81 11.6 The solar flux percentage loss due to fixed solar arrays as a function of true anomaly 81 12.1 An overview of the spacecraft bus . 88 12.2 Free body diagram of launch phase .