ENB443 : Launcher Systems

1. ENB443: Launcher Systems Caption: The generic Ariane-5 (Ariane Flight 162) lifting off from the Guiana Space Centre, Europe’s spaceport at Kourou, French Guiana. Image Credit: ESA

2. Today’s Key Learning Objectives Today’s Key Content: • Examples of Launcher Systems and Rockets • Launch Sites • Launch Environment • Orbits Issues Learning Objectives: • Motivation: Why rockets important.

3. Launcher Systems: Summary • Introduction and Overview • Examples of Launcher Systems and Rockets • Launch Sites • Launch Environment • Orbits Issues

4. Introduction • Roles/attributes of Launch System: • Places S/c in orbit. • Protects S/c during launch. • Create a severe environment. • Delta-Velocity is fundamental measure of performance. • A “launcher system” involves: • One of more rocket stages. • Ground station + launch infrastructure.

5. Introduction (cont.) • Launcher system typically designed in different organisation than satellite. • Launch payload = whole s/c to be put in orbit. Everything above the “boost adaptor”. • Yet, launch process can constrain S/C design: • Lift capacity (mass and dimensions). • Severe environment during launch: • Force/shock/vibrations/pressure, etc.

6. Apogee burn Overview: Basic Orbit Injection Three distinct phases: • Vertical launch, followed by turn manoeuvre. • Elliptical ballistic trajectory • Orbit insertion burn at orbit apogee. Image Credit: NASA

7. Overview: Basic Orbit Injection Image Credit: braeunig

8. Overview: Basic Launch Equation • Basic performance characterised by velocity. • We can estimated the velocity required from the launch vehicle as: where

9. Overview: Launch Losses The actual losses experienced are system dependent. Image Credit: SMAD, p. 722

10. Overview: Launch Reliability • Has slowly increased from 0.85 to 0.95 in the last 30 years. Image Credit: SMAD, p. 727

11. Overview: Basic S/C Deployment Options • 3 main deployment options: • Direct injection by launch system. • Using various vehicle/stage configurations. • Injection using integral propulsion system (kick stage). • Small payloads typically use option 1. • GEO satellites typically need to augment launch vehicles with upper stage. • Third option allows us to both orbit injection and maintain orbit/attitude (if engine restart possible).

12. Overview: Option 2 - Upper Stage • An extra stage added to launch system • Not part of satellite. • Different from integral propulsion system (or “Kick” motor). • Discarded during transfer orbit or once final orbit reached. • Once discarded, designed to avoid other GEO satellites.

13. Launcher Systems: Overview Orbit insertion Burn: Upper stage? Launcher stage burns Image Credit: N. A. Bletsos

14. Launcher Systems: Summary • Introduction and Overview • Examples of Launcher Systems and Rockets • Shuttle/ESA • Rocket stages • Upper Stages. • Launch Sites • Launch Environment • Orbits Issues

15. A bit dated.. Up to Delta IV and Atlas V. Notes: - Both mass and dimensional constraints. - Mass constraints depend on desired orbit. Ariane 5 ECA is a higher capacity Ariane 5 Generic launcher. Designed to place up to 9 tonne in GTO (geosynchronous transfer orbit). GTO means mass placed on Holmann Transfer orbit to GEO. Apogee burn required at GEO. Image Credit: SMAD, p. 728

16. GTO: Transfer orbit? Apogee burn required at GEO. GEO Or Holmann transfer orbit Typ. Low earth orbit Image Credit: Braeunig

17. Space Shuttle: From Nixon (1972) to 2010 An expressive commercial option.. Real cost > 6 times Atlas-Centaur or Ariane cost. By 2010 phase-out 131 successful missions over a 30 year life. In 1973, was “sold” as 580 missions over 12 years.

18. ESA Launcher System: Current • An Ariane 5G rocket engine Image Credit: ESA

19. Rocket Engines Stages Some pictures of: • Liquid • RL10 • RS-68 • Solid • Atlas V solid rocket motor (booster stage) • Note: Atlas V has liquid stages, and various configurations.

20. RS-68 • The Delta IV RS-68 main engine is the world's most powerful hydrogen/oxygen engine. • Bi-propellant Image Credit: NASA

21. Image Credit: International Launch Services Atlas V solid rocket motor

22. RL10 • The RL10 engine propels the Delta IV and Atlas V upper stages to their final orbit for payload delivery. • Initial version used in the Surveyor program (Late 1960s). Upgrade version, still used today… 45 years.. Image Credit: US Air Force

23. Upperstages Image Credit: SMAD, p. 730

24. Launcher Systems: Summary • Introduction and Overview • Examples of Launcher Systems and Rockets • Launch Sites • Sites • Direction • Launch Related Orbit Issues • Launch Environment • Orbits Issues

25. Launch Sites • Launch from near the equator is preferred: • To take maximum advantage of easterly rotation of the Earth. • Launch from higher latitudes cannot easily access orbit inclination below their latitude. • 1 degree of inclination change ~ 210m/s delta-v in LEO. • The Delta-V cost of inclination changes decreases with altitude. Hence ??? • are typically done towards the end of the transfer orbit.

26. Image Credit: SMAD, p. 733 Launch Sites

27. Image Credit: SMAD, p. 734 Launch Directions Western Range Eastern Range Why not out here? Retrograde launch

28. Launch Performance Mini-Quiz: Which system to put 10,000kg in LEO? Answer: Assume LEO is 300km, then red box suggests: Proton, Titan IV or Zenit. Image Credit: SMAD, p. 729

29. Polar Launch performance Image Credit: SMAD, p. 729

30. Launcher Systems: Summary • Introduction and Overview • Examples of Launcher systems and Rockets • Launch Sites • Launch Environment • Accelerations and Shocks • Vibration and Fundamental Frequencies • Pressure • Orbits Issues Sort of numbers might be required in structure sub-system design

31. Launch Acceleration loads. During several important events. Image Credit: SMAD, p. 740

32. Image Credit: SMAD, p. 741 Fundamental Frequencies. Payload/boost-adaptor stiffness should be above these.

33. Image Credit: SMAD, p. 740 Vibration loads But payload/adaptor stiffness should avoid these. That is, dampen vibration energy at these frequencies.

34. Image Credit: SMAD, p. 741 Shock Environment. Often payload separation by pyrotechnic device. Causes a shock load. For example:

35. High pressure Fairing and Pressure Low pressure Must withstand and vent pressure differentials Image Credit: SMAD, p. 737

36. Image Credit: SMAD, p. 739 Launch Differential Pressures

37. Launcher Systems: Summary • Introduction and Overview • Examples of Launcher Systems and Rockets • Launch Sites • Launch Environment • Orbits Issues • Accuracy • Ground tracks • Orbital Transfers

38. Injection Accuracy • Important because injection errors typically need to be corrected: • Often the job of the last stage of launcher. • Might require some of the mission delta-v budget.

39. Image Credit: SMAD, p. 138 Ground Tracks L =change in longitude

40. Points from Figure • E is geosynchronous. • Question: Period of E is ? • Answer: 1436 mins (matching Earth rotation). • An orbit’s inclination can be determined by the ground tracks maximum latitude. (SMAD p. 138). • Question: Geostationary has a maximum latitude of? • Answer=0 degrees (ie. at/above the equator). • Retrograde orbit track ground tracking in an westerly direction. (Direct orbits shown in the figure).

41. Least Energy Transfer Image Credit: Braeunig

42. Fastest Transfer These are larger Image Credit: Braeunig

43. Transfer Orbits Image Credit: SMAD, p. 185 • Often, satellite is initially placed in low-earth orbit. • Must transition to operational orbit. Remember their low thrust profile

44. Today’s Key Learning Objectives Today’s Key Content: • Examples of Launcher Systems and Rockets • Launch Sites • Launch Environment • Orbits Issues Learning Objectives: • Motivation: Why rockets important.