Powered Space Flight - 東京大学PoweredSpaceFlight).pdfPropulsion and Energy Systems; Dec. 7th...
Transcript of Powered Space Flight - 東京大学PoweredSpaceFlight).pdfPropulsion and Energy Systems; Dec. 7th...
Propulsion and Energy Systems; Dec. 7th (2015)
Powered Space Flight KOIZUMI Hiroyuki
(小泉 宏之)
Graduate School of Frontier Sciences, Department of Advanced Energy
& Department of Aeronautics and Astronautics
(基盤科学研究系 先端エネルギー工学専攻,工学系航空宇宙工学専攻兼担)
Propulsion and Energy Systems; Dec. 7th (2015)
1. Introduction
2. Fundamentals of orbit
Purpose of today’s lecture
Scope of Today’s Lecture
to learn “Powered Space Flight” using electric propulsion by actual orbit examples
3. Examples of powered flights
3.1 HAYABUSA
3.2 DAWN
3.3 Boeing 702SP
Contents
Propulsion and Energy Systems; Dec. 7th (2015)
1. Introduction
2. Fundamentals of orbit
Purpose of today’s lecture
Scope of Today’s Lecture
to learn “Powered Space Flight” using electric propulsion by actual orbit examples
3. Examples of powered flights
3.1 HAYABUSA
3.2 DAWN
3.3 Boeing 702SP
Contents
What is
“Powered Space Flight” ?
Propulsion and Energy Systems; Dec. 7th (2015)
How to change orbits ?
Adding energy (or velocity) changes the orbits
Energy: depends on the mass
Velocity: as specific energy
Velocity increment, Delta-V (ΔV), is the index of Powered Space Flight
©JAXA
Powered space flight is flight using a propulsion device to control the trajectory by ΔV maneuvers
Propulsion is a device to provide ΔV
Propulsion and Energy Systems; Dec. 7th (2015)
Chemical & Electric Propulsion
Chemical propulsion
Electric Propulsion
Chemical E (inside propellant) → Kinetic E
Propulsive device = Device exhausting propellant by adding energy on it = Energy converter (from any source to kinetic energy)
Electrical E (Solar, Nuclear) → Kinetic E
Exhaust V:1 – 4 km/s
Exhaust V:10 – 50 km/s
Propulsion and Energy Systems; Dec. 7th (2015)
Chemical & Electric Propulsion
Chemical propulsion
Electric Prouplsion
ΔV: 4– 5 km/s
Exhaust V:3 km/s
Exhaust V:30 km/s
Propellant
Payload = 200–400%
Propellant
Payload = 14–18%
1 ton Car + 150 kg gas
+ 3 ton gas 1 ton Car
1exp
Exhaust
PayloadPropellantv
VMM
Propulsion and Energy Systems; Dec. 7th (2015)
Saving propellant
Low cost by decreasing S/C weight
High quality by increasing equipment
Merit of EP 1)
Propulsion and Energy Systems; Dec. 7th (2015)
Merit of EP 2)
Electric propulsion gives us freedom to travel
Chemical propulsion
Your journey (orbit) is pre-fixed
You can freely change the journey as you do in the journey on the ground
Electric propulsion
Flexibility & Redundancy are increased
Excessive propellant
My opinion: “True” powered space flight needs
Electric Propulsion
Propulsion and Energy Systems; Dec. 7th (2015)
1. Introduction
2. Fundamentals of orbit
Purpose of today’s lecture
Scope of Today’s Lecture
to learn “Powered Space Flight” using electric propulsion by actual orbit examples
3. Examples of powered flights
3.1 HAYABUSA
3.2 DAWN
3.3 Boeing 702SP
Contents
Propulsion and Energy Systems; Dec. 7th (2015)
Motion in space
on the ground in space
Free-form path governed by celestial bodies
©JAXA
Propulsion and Energy Systems; Dec. 7th (2015)
Equation of Motion
M>>m
Position of the S/C
Thrust
Standard gravitational parameter: 𝐺𝑀
Massive body Spacecraft
: thrust
𝑑2
𝑑𝑡2𝒓 = −
𝜇
𝑟2𝒓 +
𝑭 𝑡
𝑚
𝑀
𝑟
𝑚
𝑭(𝑡)
Propulsion and Energy Systems; Dec. 7th (2015)
Two-body Problem w/o thrust
Ellipse Hyperbola Parabola
Three types
Propulsion and Energy Systems; Dec. 7th (2015)
Orbit Terminology Apoapsis
Periapsis
a: Semi-major axis
Perigee
Semi-minor axis
Apogee
Apolune Perilune
Perihelion Aphelion
e: Eccentricity ea
Focus Peri Apo
Sun
Earth
Moon
Propulsion and Energy Systems; Dec. 7th (2015)
Initial velocity and its orbit
V: small
V: middle
V: large
Ellipse (from apoapsis)
Circle
Ellipse (from periapsis)
Propulsion and Energy Systems; Dec. 7th (2015)
Typical trajectory by CP
Orbital period >> Thrusting time
Impulse approximation
Connect the analytical solutions of I.C. problem of Momentum eq.
©JAXA
Propulsion and Energy Systems; Dec. 7th (2015)
Typical Trajectories of EP ; Spiral
Tangential thrust
Spiral orbit
Gradual orbit raising/lowering
T = 25 mN Msc = 500 kg 1000 days
Propulsion and Energy Systems; Dec. 7th (2015)
Typical Trajectories of EP ; Deform.
Constant Thrust
Eccentricity change
Earth gravity assist Ellipse to/from Circle
T = 25 mN Msc = 500 kg 1000 days
Orbit raising and lowering
Propulsion and Energy Systems; Dec. 7th (2015)
1. Introduction
2. Fundamentals of orbit
Purpose of today’s lecture
Scope of Today’s Lecture
to learn “Powered Space Flight” using electric propulsion by actual orbit examples
3. Examples of powered flights
3.1 HAYABUSA
3.2 DAWN
3.3 Boeing 702SP
Contents
Propulsion and Energy Systems; Dec. 7th (2015)
HAYABUSA
Feature: Return trip using electric propulsion
Mission: Sample return of a small asteroid
©JAXA
Propulsion and Energy Systems; Dec. 7th (2015)
ITOKAWA (small asteroid)
500 m
Orbit specifications
Semi-major axis: Aphelion: Perihelion: Eccentricity: Inclination:
35,000,000 ton
ITOKAWA; the asteroid
1.32 AU 1.70 AU 0.95 AU 0.28 1.6 deg
©JAXA
Propulsion and Energy Systems; Dec. 7th (2015)
HAYABUSA’s journey
2003-2004 Delta-V for Earth Gravity Assist
2004-2005 Delta-V for rendezvous with ITOKAWA
2007-2010 Delta-V for reentry to the Earth
ITOKAWA touch down
Some troubles
Propulsion and Energy Systems; Dec. 7th (2015)
Trajectory from Earth to ITOKAWA
Earth HAYABUSA
ITOKAWA
Departure (2003, May 9th)
Earth gravity assist (2004, May 19th)
Sun
Propulsion and Energy Systems; Dec. 7th (2015)
In the case of free flight
HAYABUSA was launched with hyperbolic excess velocity: 3.2 km/s
Sun orbital velocity: 29.8 km + Initial ΔV 3.2 km/s
Departure
Earth
Spacecraft
Unit is AU (astronomical unit) 1 AU = Sun-Earth distance
= 150 Million km
Propulsion and Energy Systems; Dec. 7th (2015)
In the case of free flight
HAYABUSA orbit on
Earth
Spacecraft
Sun direction
Unit is AU (astronomical unit) 1 AU = Sun-Earth distance
Spacecraft does not meet with the Earth
Propulsion and Energy Systems; Dec. 7th (2015)
In the case of free flight
Earth
Thrust off
Sun direction
With thrust (18 mN average)
Thrust on
HAYABUSA orbit on
Spacecraft meets with the Earth
Gravity assist
Propulsion and Energy Systems; Dec. 7th (2015)
Real HAYABUSA orbit
©JAXA
June 24th
July 29th
Aug. 4th
Sep. 3rd
Oct. 2nd
Oct. 29th
Dec. 3rd
in 2003
©JAXA
Propulsion and Energy Systems; Dec. 7th (2015)
Earth Gravity Assist
Velocity increment: 4 km/s
Alt. 3700 km
Required accuracy is Position: 1 km Velocity: 1 cm/s
©JAXA
Propulsion and Energy Systems; Dec. 7th (2015)
Gravity Assist; Principle
Moving wall
Propulsion and Energy Systems; Dec. 7th (2015)
Hyperbolic Trajectory
Hyperbola
ui
uf = R(θ*)ui
θ* Scattering angle
Collision parameter b
bu22
*tan
Propulsion and Energy Systems; Dec. 7th (2015)
GA = Velocity Rotation
θ*
ui
Vp
vsc,i
vsc,f
β
ui = vsc,i - Vp
Red arrows: S/C inertial velocity
Black arrows: S/C relative velocity
uf
Green arrow: Planet inertial velocity
Propulsion and Energy Systems; Dec. 7th (2015)
Accurate Trajectory Control for GA
Collision parameter: b
Scattering angle: θ*
Gravity assist
Planet velocity
Spacecraft velocity
Orbit scale
Planet scale
1 AU = 150,000,000 km
To get 90 deg scattering b = 4,4000 km (relative V : 3 km/s, Earth)
Accurate Orbit Control is required
Propulsion and Energy Systems; Dec. 7th (2015)
Trajectory from Earth to ITOKAWA
Earth HAYABUSA
ITOKAWA
Departure (2003, May 9th)
Earth gravity assist (2004, May 19th)
Sun
©JAXA
Propulsion and Energy Systems; Dec. 7th (2015)
Toward the ITOKAWA
Rendezvous
Position & Velocity must be matched
Orbits of two objects must be matched
Propulsion and Energy Systems; Dec. 7th (2015)
Toward the ITOKAWA
The semi-major axes
ITOKAWA: 1.32 AU
Hayabusa :1.37 AU (after the GA)
Earth: 1.00 AU
Ion thruster Delta-V : reducing the perihelion (deceleration)
Aphelion matching
Propulsion and Energy Systems; Dec. 7th (2015)
Return to Earth
Outward journey
Homeward journey
Rendezvous with ITOKAWA
Reentry to the Earth
Position & velocity must be exactly matched
Only position must be matched
Delta-V requirement is lower Troubles
Propulsion and Energy Systems; Dec. 7th (2015)
1. Introduction
2. Fundamentals of orbit
Purpose of today’s lecture
Scope of Today’s Lecture
to learn “Powered Space Flight” using electric propulsion by actual orbit examples
3. Examples of powered flights
3.1 HAYABUSA
3.2 DAWN
3.3 Boeing 702SP
Contents
Propulsion and Energy Systems; Dec. 7th (2015)
DAWN
Weight:1250 kg
by NASA JPL DAWN
NSTAR
90 mN ion thruster
3 kW
3100 s
Mission: rendezvous with asteroids
ΔV : 11 km/s (Ion propulsion)
Propellant: 400 kg
©NASA
Propulsion and Energy Systems; Dec. 7th (2015)
NSTAR ion engine (NASA)
Deep Space 1(1998): Flyby of comet
Single NSTAR
Demonstration of NSTAR (16 k-hours operation)
DAWN(2007-): Asteroid probe
Three NSTARs NSTAR engine
Thrust 93 mN
Isp 3100 s
Power 2550 W
Efficiency 62 %
Beam D. 29 cm
©NASA
©NASA
Vesta
Ceres
The second most massive
The most massive
530 km
950 km
©NASA
©NASA
Propulsion and Energy Systems; Dec. 7th (2015)
Spiral orbit raising
Launch, 2007 Sept.
Spiral orbit raising
Earth
Ceres
Vesta Thrust on
Thrust off
Propulsion and Energy Systems; Dec. 7th (2015)
Spiral orbit raising
・Tangential thrust to the orbit ・Assuming the circular orbit
FVdt
dE
r
μm
r
μmmVE
22
1 2
r
μF
dt
dr
r
μm
22 )/)(( 12
21
mttFV
VVV
Spiral orbit raising requires ΔV equal to the difference between the initial orbit and the final orbit
©JAXA
Propulsion and Energy Systems; Dec. 7th (2015)
Let’s estimate the thrust of DAWN
Spacecraft momentum change = given impulse
FTVM SC
DAWN wet mass = 1250 kg Xenon propellant = 425 kg
Get from the orbit and events
kg 1000SCM
km/s 9.11V
? T
Propulsion and Energy Systems; Dec. 7th (2015)
Phase-1; from Earth to Mars
Earth
Three thrusting phases
1. Earth departure – Mars gravity assist
600 days = Mars GA (Feb 2009) - Launch (Oct 2007) - Mars period/6
687 days
Propulsion and Energy Systems; Dec. 7th (2015)
Phase-2; from Mars to Vesta
Earth
Three thrusting phases
2. Mars gravity assist – Vestra arrival
550 days = Vesta arv. (July 2011) - Mars GA (Feb 2009) - Mars period/6
Propulsion and Energy Systems; Dec. 7th (2015)
Phase-3; Vesta to Ceres
Earth
Three thrusting phases
3. Vesta departure – Ceres arrival
950 days = Vesta dept. (July 2012) - Ceres arrv. (Feb 2015)
Propulsion and Energy Systems; Dec. 7th (2015)
Let’s estimate the thrust of DAWN
FTVM SC
S/C mass (average):1000 kg
Estimate: 65 mN
Thrusting time:2100 days (550 + 600 + 950)
ΔV:11.9 km/s
「 John R. Brophy et al.,J. Propul. Power 25(2009)」
Actual: 91 mN
Propulsion and Energy Systems; Dec. 7th (2015)
Solar power is decreasing
Earth:1 AU
Ceres: 2.8 AU
Solar power at Ceres is
1/2.82 (= 13%) of Earth
Solar power averaged from Earth to Ceres is 57% of Earth
Estimated: 65 mN
Actual: 91 mN
70% Good estimation!
Propulsion and Energy Systems; Dec. 7th (2015)
Very low power near Ceres
Earth
Phase 1+2 (Earth to Vesta)
Phase 3 (Vesta to Ceres)
Spiral ΔV = 1.5 km/s
Period = 950 days
Spiral ΔV = 10.4 km/s
Period = 1150 days
Estimated F = 105 mN
Estimated F = 18 mN
Over 90 mN is caused by initial dV & Mars GA
Propulsion and Energy Systems; Dec. 7th (2015)
1. Introduction
2. Fundamentals of orbit
Purpose of today’s lecture
Scope of Today’s Lecture
to learn “Powered Space Flight” using electric propulsion by actual orbit examples
3. Examples of powered flights
3.1 HAYABUSA
3.2 DAWN
3.3 Boeing 702SP
Contents
Propulsion and Energy Systems; Dec. 7th (2015)
GEO: Geostationary Earth Orbit
24 hrs/cycle
90 min/cycle
600 km 36000 km
Communication satellite
Broadcasting satellite
©JAXA
Propulsion and Energy Systems; Dec. 7th (2015)
Disturbances from Sun and Moon
GEO:on equatorial plane
Sun, moon, planets: on ecliptic plane
Sun and Moon gravity forces are disturbances to GEO S/C
Propulsion and Energy Systems; Dec. 7th (2015)
North South Station Keeping
Maintaining the orbit plane requires ΔV of 50 m/s per year
(NSSK: north south stationkeeping)
Eelectric(3000 s)
Chemical (200 s)
Propellant: 50 kg
Propellant: 850 kg
3 ton+10 year operation
Propulsion and Energy Systems; Dec. 7th (2015)
Orbit transfer from GTO to GEO
ΔV (GTO → GEO) =1500 m/s
GTO: GEO Transfer Orbit (insertion by a rocket)
GEO
©JAXA
Propulsion and Energy Systems; Dec. 7th (2015)
By all EP, mass becomes half
ΔV = 500 + 1500 m/s
1expSatPropellant
eu
VMM
Msat = 2.0 ton
MPropellant = 1.9 ton
MPropellant = 0.14 ton
by Chemical
by Electric
Propulsion and Energy Systems; Dec. 7th (2015)
Disadvantage-1; long time
GEO longer time
Time (GTO→GEO)
CP:half day
EP:half year
©JAXA
Propulsion and Energy Systems; Dec. 7th (2015)
Disadvantage-2; radiation
Passing Van-Allen belt Electron belt
Proton belt damage to electronics
©JAXA
Propulsion and Energy Systems; Dec. 7th (2015)
1. Introduction
2. Fundamentals of orbit
Purpose of today’s lecture
Scope of Today’s Lecture
to learn “Powered Space Flight” using electric propulsion by actual orbit examples
3. Examples of powered flights
3.1 HAYABUSA
3.2 DAWN
3.3 Boeing 702SP
Contents