ASEN 5050 SPACEFLIGHT DYNAMICS Interplanetary

Transcription

1 ASEN 5050 SPACEFLIGHT DYNAMICS Interplanetary Prof. Jeffrey S. Parker University of Colorado Boulder Lecture 28: Interplanetary 1

2 Announcements HW 8 is out now! Due in one week: Wednesday, Nov 12. J2 effect Using VOPs Mid-Term handed back today! Concept quiz after today s lecture, due 8 am Friday Not quite ready, but I ll send out an . Reading: Chapter 12 Lecture 28: Interplanetary 2

3 11/5: Interplanetary 1 11/7: Interplanetary 2 Schedule from here out 11/10: Entry, Descent, and Landing 11/12: Low-Energy Mission Design 11/14: STK Lab 3 11/17: Low-Thrust Mission Design (Jon Herman) 11/19: Finite Burn Design 11/21: STK Lab 4 Fall Break 12/1: Constellation Design, GPS 12/3: Spacecraft Navigation 12/5: TBD 12/8: TBD 12/10: TBD 12/12: Final Review Lecture 28: Interplanetary 3

4 Final Project Due 12/18. If you turn it in by 12/12, I ll forgive 5 pts of deductions. Worth 20% of your grade, equivalent to 6-7 homework assignments. Final Exam is worth 25%. Find an interesting problem and investigate it anything related to spaceflight mechanics (maybe even loosely, but check with me). Requirements: Introduction, Background, Description of investigation, Methods, Results, Conclusions, References. You will be graded on quality of work, scope of the investigation, and quality of the presentation. The project will be built as a webpage, so take advantage of web design as much as you can and/ or are interested and/or will help the presentation. Lecture 28: Interplanetary 4

5 Final Project Instructions for delivery of the final project: Build your webpage with every required file inside of a directory. Name the directory LastName_FirstName i.e., Parker_Jeff/ there are a lot of duplicate last names in this class! You can link to external sites as needed. Name your main web page index.html i.e., the one that you want everyone to look at first Make every link in the website a relative link, relative to the directory structure within your named directory. We will move this directory around, and the links have to work! Test your webpage! Change the location of the page on your computer and make sure it still works! Zip everything up into a single file and upload that to the D2L dropbox. Lecture 28: Interplanetary 5

6 HTML If you ve never coded in HTML, don t fret (but don t wait to try it out). Lots of tutorials online One student suggested this page for HTML tutorials: Think of a webpage as a blank canvas, fill it with invisible tables, lists, links, animations, pictures, and text. Word, LaTex, and other programs can save documents as HTML, but then it s awful to edit / personalize. Lecture 28: Interplanetary 6

7 Space News China s lunar swingby vehicle successfully landed. Philae lands next week. Neat video of the Aurora Australis, viewed from the ISS: aurora-new-zealand-space-station/ / Lecture 28: Interplanetary 7

8 ASEN 5050 SPACEFLIGHT DYNAMICS Mid-Term Prof. Jeffrey S. Parker University of Colorado Boulder Lecture 28: Interplanetary 8

9 High score: 98 Mean: 88 Statistics I tried my best to knock down your grades, but couldn t find many holes. Lecture 28: Interplanetary 9

10 ASEN 5050 SPACEFLIGHT DYNAMICS Interplanetary Prof. Jeffrey S. Parker University of Colorado Boulder Lecture 28: Interplanetary 10

11 Destination Mercury Venus Mars Asteroids, Comets Jupiter Saturn Missions Mariner 10, MESSENGER LOTS LOTS Uranus Voyager 2 Neptune Voyager 2 Pluto / KBO Interplanetary Missions ISEE-3/ICE, NEAR, Deep Impact, Galileo, Dawn, Rosetta, etc. Pioneer 10, 11, Voyager 1, 2, Ulysses, Galileo, Cassini, New Horizons, Juno Pioneer 11, Voyager 1, 2, Cassini New Horizons Lecture 28: Interplanetary 11

12 History of Interplanetary Exploration Earth This timeline may be found here: Moon Moon 1 st Mission to get close to the Moon 1 st Mission to impact the Moon Lecture 28: Interplanetary 12

13 History of Interplanetary Exploration Moon Mars Moon Venus Moon 1 st Mission to fly by Venus Moon Venus Americans fly by Venus Moon Mars Lecture 28: Interplanetary 13

14 History of Interplanetary Exploration Americans successfully impact the Moon First Mars Flyby Lecture 28: Interplanetary 14

15 History of Interplanetary Exploration 1 st Soft Lunar Landing 1 st American soft lunar landing Lecture 28: Interplanetary 15

16 History of Interplanetary Exploration 1 st Venus Atmospheric probe Lecture 28: Interplanetary 16

17 History of Interplanetary Exploration Humans are at the Moon! Humans are at the Moon! Lecture 28: Interplanetary 17

18 History of Interplanetary Exploration Apollo Nuff Said Apollo Apollo Robotic lunar sample return Robotic lunar rover Lecture 28: Interplanetary 18

19 History of Interplanetary Exploration Apollo Mars orbiters Apollo 1 st Mission to Jupiter! Apollo Apollo Final Apollo mission Lecture 28: Interplanetary 19

20 History of Interplanetary Exploration 1 st Mission to Saturn! 1 st Mission to Mercury 1 st Mars lander Lecture 28: Interplanetary 20

21 History of Interplanetary Exploration Grand Tour 1 st libration orbiter and Comet flyby Lecture 28: Interplanetary 21

22 History of Interplanetary Exploration 1 st Japanese mission 1 st ESA mission 1 st Jupiter Orbiter 1 st Low-Energy Lunar Transfer Lecture 28: Interplanetary 22

23 History of Interplanetary Exploration 1 st Asteroid Orbiter 1 st Mars Rover 1 st Saturn Orbiter Lecture 28: Interplanetary 23

24 History of Interplanetary Exploration 1 st Comet Sample Return 1 st Asteroid Sample Return 1 st Low-Thrust Lunar Transfer 1 st Mercury Orbiter 1 st Comet Impact Lecture 28: Interplanetary 24

25 History of Interplanetary Exploration 1 st Mission to Pluto/KBOs 1 st Low-Thrust to Main Belt Asteroids 1 st Chinese mission 1 st Indian mission Lecture 28: Interplanetary 25

26 Ongoing exploration at Mars Human exploration aiming for Mars Waypoints may include the Moon, L2, Asteroids, and/or Phobos/ Deimos. Europa Enceladus Titan Lakes Uranus/Neptune systems Other stars!? Future Exploration Plenty of proposals being submitted for every major (and many minor) destinations in the solar system. Lecture 28: Interplanetary 26

27 Interplanetary Trajectories Pioneer 10 s Interplanetary Trajectory Earth Jupiter Lecture 28: Interplanetary 27

28 Interplanetary Trajectories Pioneer 11 s Interplanetary Trajectory Earth Jupiter Saturn Lecture 28: Interplanetary 28

29 Interplanetary Trajectories Mariner 10 s Interplanetary Trajectory Earth Venus Mercury Lecture 28: Interplanetary 29

30 Interplanetary Trajectories Voyager 1 s and Voyager 2 s Interplanetary Trajectories: Earth Jupiter Saturn & Beyond Lecture 28: Interplanetary 30

31 Interplanetary Trajectories Galileo s Trajectory to Jupiter VEEGA (Venus Earth Earth Gravity Assist) Lecture 28: Interplanetary 31

32 Interplanetary Trajectories Cassini s Trajectory to Saturn VVEJGA (Venus Venus Earth - Jupiter Gravity Assist) Lecture 28: Interplanetary 32

33 Interplanetary Trajectories Ulysses Trajectory past Jupiter Image courtesy of: Planetary and Space Science, Volume 54, Issues 9 10, August 2006, Pages Lecture 28: Interplanetary 33

34 Interplanetary Trajectories Juno s Trajectory to Jupiter Lecture 28: Interplanetary 34

35 Interplanetary Trajectories MESSENGER s Trajectory to Mercury Lecture 28: Interplanetary 35

36 Interplanetary Trajectories DAWN s Trajectory to Main Belt Asteroids Lecture 28: Interplanetary 36

37 Moon Tours Jupiter: Galileo Lecture 28: Interplanetary 37

38 Moon Tours Saturn: Cassini Lecture 28: Interplanetary 38

39 Cassini s Extended Mission Lecture 28: Interplanetary 39

40 Cassini s Extended Mission Why are there no small body flybys here? Lecture 28: Interplanetary 40

41 Building an Interplanetary Transfer Simple: Step 1. Build the transfer from Earth to the planet. Step 2. Build the departure from the Earth onto the interplanetary transfer. Step 3. Build the arrival at the destination. Added complexity: Gravity assists Solar sailing and/or electric propulsion Low-energy transfers Lecture 28: Interplanetary 41

42 Use two-body orbits Patched Conics Lecture 28: Interplanetary 42

43 Patched Conics Gravitational forces during an Earth-Mars transfer Lecture 28: Interplanetary 43

44 Sphere of Influence Measured differently by different astrodynamicists. Hill Sphere Laplace derived an expression that matches real trajectories in the solar system very well. Laplace s SOI: Consider the acceleration of a spacecraft in the presence of the Earth and the Sun: Lecture 28: Interplanetary 44

45 Sphere of Influence Motion of the spacecraft relative to the Earth with the Sun as a 3 rd body: Motion of the spacecraft relative to the Sun with the Earth as a 3 rd body: Lecture 28: Interplanetary 45

46 Sphere of Influence Laplace suggested that the Sphere of Influence (SOI) be the surface where the ratio of the 3 rd body s perturbation to the primary body s acceleration is equal. Lecture 28: Interplanetary 46

47 Sphere of Influence Laplace suggested that the Sphere of Influence (SOI) be the surface where the ratio of the 3 rd body s perturbation to the primary body s acceleration is equal. Primary Earth Accel 3 rd Body Sun Accel Primary Sun Accel 3 rd Body Earth Accel Lecture 28: Interplanetary 47

48 Sphere of Influence Laplace suggested that the Sphere of Influence (SOI) be the surface where the ratio of the 3 rd body s perturbation to the primary body s acceleration is equal. Primary Earth Accel 3 rd Body Sun Accel = Primary Sun Accel 3 rd Body Earth Accel Lecture 28: Interplanetary 48

49 Sphere of Influence Find the surface that sets these ratios equal. After simplifications: Lecture 28: Interplanetary 49

50 Sphere of Influence Find the surface that sets these ratios equal. Earth s SOI: ~925,000 km Moon s SOI: ~66,000 km Lecture 28: Interplanetary 50

51 Use two-body orbits Patched Conics Lecture 28: Interplanetary 51

52 Interplanetary Transfer Use Lambert s Problem Earth Mars in 2018 Lecture 28: Interplanetary 52

53 Interplanetary Transfer Lambert s Problem gives you: the heliocentric velocity you require at the Earth departure the heliocentric velocity you will have at Mars arrival Build hyperbolic orbits at Earth and Mars to connect to those. V-infinity is the hyperbolic excess velocity at a planet. Lecture 28: Interplanetary 53

54 Earth Departure We have v-infinity at departure Compute specific energy of departure wrt Earth: Compute the velocity you need at some parking orbit: Lecture 28: Interplanetary 54

55 Earth Departure Departing from a circular orbit, say, 185 km: Lecture 28: Interplanetary 55

56 Launch Target Lecture 28: Interplanetary 56

57 Launch Target Outgoing V Vector Locus of all possible interplanetary injection points Lecture 28: Interplanetary 57

58 C 3, RLA, DLA Launch Targets Lecture 28: Interplanetary 58

59 Launch Targets Lecture 28: Interplanetary 59

60 Mars Arrival Same as Earth departure, except you can arrive in several ways: Enter orbit, usually a very elliptical orbit Enter the atmosphere directly Aerobraking. Aerocapture? Lecture 28: Interplanetary 60

61 Aerobraking Lecture 28: Interplanetary 61

62 Comparing Patched Conics to High- Fidelity Lecture 28: Interplanetary 62

63 Gravity Assists A mission designer can harness the gravity of other planets to reduce the energy needed to get somewhere. Galileo launched with just enough energy to get to Venus, but flew to Jupiter. Cassini launched with just enough energy to get to Venus (also), but flew to Saturn. New Horizons launched with a ridiculous amount of energy and used a Jupiter gravity assist to get to Pluto even faster. Lecture 28: Interplanetary 63

64 Gravity Assists Gravity assist, like pretty much everything else, must obey the laws of physics. Conservation of energy, conservation of angular momentum, etc. So how did Pioneer 10 get such a huge kick of energy, passing by Jupiter? Lecture 28: Interplanetary 64

65 Designing Gravity Assists Rule: Unless a spacecraft performs a maneuver or flies through the atmosphere, it departs the planet with the same amount of energy that it arrived with. Guideline: Make sure the spacecraft doesn t impact the planet (or rings/moons) during the flyby, unless by design. Turning Angle ~V out 1 ~V 1 in r p = µ planet V 2 1 E = ~ V ~ V out 1 = ~ V in Lecture 28: Interplanetary 65 cos A

66 How do they work? Use Pioneer 10 as an example: OUT OF FLYBY INTO FLYBY ~V sun sc = ~ V 1 + ~ V sun jup V sun sc V sun jup V sun jup ~V 1 ~ V out 1 = ~ V in 1 ~V 1 = ~ V sun sc ~V sun jup Lecture 28: Interplanetary 66

67 Gravity Assists We assume that the planet doesn t move during the flyby (pretty fair assumption for initial designs). The planet s velocity doesn t change. The gravity assist rotates the V-infinity vector to any orientation. Check that you don t hit the planet V sun jup V sun jup V sun sc ~V 1 ~V 1 = ~ V sun sc ~V jup sun ~V 1 Lecture 28: Interplanetary 67

68 Gravity Assists We assume that the planet doesn t move during the flyby (pretty fair assumption for initial designs). The planet s velocity doesn t change. The gravity assist rotates the V-infinity vector to any orientation. Check that you don t hit the planet V sun jup V sun sc V sun jup ~V 1 ~V 1 = ~ V sun sc ~V jup sun Lecture 28: Interplanetary 68 ~V 1

69 Designing a Gravity Assist Build a transfer from Earth to Mars (for example) ~V 1 in Defines at Mars Build a transfer from Mars to Jupiter (for example) ~V 1 out Defines at Mars Check to make sure you don t break any laws of physics: r p = µ planet V 2 1 ~ V out 1 = ~ V in cos A Lecture 28: Interplanetary 69 1

70 Gravity Assists Please note! This illustration is a compact, beautiful representation of gravity assists. But know that the incoming and outgoing velocities do NOT need to be symmetric about the planet s velocity! This is just for illustration. Lecture 28: Interplanetary 70

71 Gravity Assists We can use them to increase or decrease a spacecraft s energy. We can use them to add/remove out-of-plane components Ulysses! We can use them for science Lecture 28: Interplanetary 71