1 / 24

ORBITALS Phase A Extended Interim Meeting U of A Phase A2 Work Update

ORBITALS Phase A Extended Interim Meeting U of A Phase A2 Work Update. ORBITALS Science Team, University of Alberta CSA HQ, St. Hubert, 2010/03/17. WP 2.1.1 Launch and Orbit. Work by Louis Ozeke New 8 hour period orbit with magnetic conjunctions to multiple ground segments

kedem
Télécharger la présentation

ORBITALS Phase A Extended Interim Meeting U of A Phase A2 Work Update

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ORBITALS Phase A ExtendedInterim Meeting U of A Phase A2 Work Update ORBITALS Science Team, University of Alberta CSA HQ, St. Hubert, 2010/03/17

  2. WP 2.1.1 Launch and Orbit • Work by Louis Ozeke • New 8 hour period orbit with magnetic conjunctions to multiple ground segments • Review science return from orbit options for tomorrows launch/orbit discussion ORBITALS Mission Orbit Analysis and Science Impact (D2.1.1.1, D2.1.1.3) P1, 2010/02/28

  3. 3.5.1 Primary Science Objective:1. Understand the dynamical variation of outerradiation belt electron flux, including determining the dominant acceleration and loss processes.3.5.2 Secondary Science Objectives:2. Understand the dynamical behaviour ofinner zone and slot region radiation belt particle fluxes.3. Understand the structure of global inner magnetospheric electric and magnetic fields.4. Understand the core ion composition of the outer plasmasphere, plasmapause and plasmatrough regions and its dynamics during storms. Science Objectives

  4. Outer, Inner and Slot Regions Outer Belt 3 Re – 6 Re Inner Belt 1 Re – 2 Re Slot Region 2 Re – 3 Re All distances are geocentric in the equatorial plane

  5. Orbit Parameters for Candidate Options

  6. Daily Averaged Worst Case Electron and Proton Integral Flux (AE-8/AP-8 and CRRES ELE/PRO models) For protons > 50 MeV the flux is more than an order of magnitude greater along the low perigee orbits. The risk of SEU maybe greater at lower perigee. For electrons the flux is the same for raised & lower perigee orbit options at these energies. Deep dielectric charging risk may not depend on the orbit choice.

  7. ULTIMA Magnetometers (as of 2006)

  8. New 8 hrs period orbit option • A new orbit option with 3 orbits/day has been examined. • This orbit option has magnetic conjunctions with different magnetometer arrays at each apogee pass. • To obtain the 8 hr period the apogee has had to be reduced to ~5.24 Re (radial geocentric distance) for a perigee of 750 km.

  9. Magnetic Footprints along the 3 petal orbit (plot shows 20 orbits) • 7.96 hr period (3orbit/day) • Apogee 27000 km (4.24 Re) • Perigee 750 km • Incl 7 degs • Dipole tilts of 10 degs & 15 degs give max L-shells of 5.7 & 6.1 • RAAN=240 degs • Argument of perigee=0 • True anomaly=0

  10. Primary Science Goal Measurement Need to measure PSD peak radial location L*=5.6 (6.3 Re in the equatorial plane for -100nT Dst). To measure particles at L=6.3 the inclination needs to be at least ~10 degs assuming dipole tilt of 15 degs ~15 degs assuming a dipole tilt of 10 degs Results taken from “The energization of relativistic electrons in the outer Van Allen radiation belt” Yue Chen, Geoffrey D. Reeves & Reiner H. W. Friedel, Nature, 2007

  11. Raised Perigee Orbit (12 hr orbit) • - Once per day apogee conjunctions with Churchill and Alberta line magnetometers • - Over an order of magnitude lower flux of > 5-10 MeV protons, reduced risk of SEU • Over 2 orders of magnitude lower flux of > 20 MeV protons, reduced risk of SEU • - Inner zone region is missed below altitudes of 1 Re • Lower Perigee Orbit (750 km no main & 375 km with main) • Once per 2 days apogee conjunctions with Churchill & Alberta line magnetometers • Good coverage of the inner zone at perigee • Increased risk of SEU due to higher flux of > ~10 MeV protons • Lower Apogee Orbit (8 hr orbit) • 3 times per day conjunctions with Church/Alberta, Japanese and European lines • Good coverage of the inner zone at perigee • Reduced coverage of outer zone; poorer conjunctions with GEO satellites. • Increased risk of SEU due to higher flux of > ~10 MeV protons also higher TID • Inclination increase needed

  12. Raised perigee Apogee conjunctions -Alberta line -Churchill line Perigee conjunctions -Europe -Japan-poor -Antarctica

  13. 375 km perigee maintenance Apogee conjunctions -Alberta line -Churchill line -Alaska station -Antarctic-poor Perigee conjunctions -Europe -Japan

  14. 750 km perigee Apogee conjunctions -Alberta line-poor -Churchill line -Alaska station -Europe-poor -Antarctic-poor Perigee conjunctions -Europe -Japan

  15. SEU rates detected on 64 Mbit DRAM (COTS) on-board MDS-1 JAXA Sample time 2.6-5.25 hrs. Er1 & Er2 are two memory slices. Taken from IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 53, NO. 4, AUGUST 2006

  16. Particle flux measurements • TID is slightly greater than the other orbit options due to greater time spent in the middle of the outer radiation belt at apogee. However TID over 2 years is < 50 krads behind 8 mm of Al so that 100 krad parts may still be used assuming an RDM of 2. • Worst case electron and proton flux is the same as the other orbit options. • 750 km perigee means measurements of the inner belt are possible.

  17. Radiation Dose over 2 years

  18. 250 km perigee. Apogee drifts through all local times in less than 6 months.

  19. What apogee can reach L=5.6* • L*=5.6 is approximately equal to a dipole L-shell of L=6.3 for a Dst of -100nT • To reach L=6.3 with the 8 hr period orbit the inclination of the spacecraft needs at least 13 degs assuming a dipole tilt of 11 degs. • If the dipole tilt is 15 degs (true in the southern hemisphere) then the inclination needs to be at least 10 degs.

  20. Dependence on apogee and perigee of the 8hr period orbit. • Dropping the perigee down to 375 km means that the apogee can be extended slightly to 27500 km and the 8hrs period is maintained. • The TID and worst case particle flux are not affected. • Orbit maintenance is needed at 375 km.

  21. Data still available from the Japanese meridian stationshttp://denji102.geo.kyushu-u.ac.jp/denji/obs/cpmn/station/map/russia.gif

  22. L-shell CoverageER102618 ORBITALS Orbit Analysis DRAFT May 16 2008(3)

  23. Raised Perigee ER102618 ORBITALS Orbit Analysis DRAFT May 16 2008 Raised perigee typically >30% more conjunctions with the Churchill and Alberta line than lower perigee orbits. 375 km Perigee main 375 km Perigee No main 750 km Perigee 250 km Perigee

  24. 375 km perigee No maintenance 5 orbits/2 days Apogee conjunctions -Alberta line -Churchill line -Alaska station -Europe -Antarctic Perigee conjunctions -Europe -Japan

More Related