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 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 (D , D ) P1, 2010/02/28

Science Objectives Primary Science Objective: 1. Understand the dynamical variation of outer radiation belt electron flux, including determining the dominant acceleration and loss processes Secondary Science Objectives : 2. Understand the dynamical behaviour of inner 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.

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

Orbit Parameters for Candidate Options Orbit Parameter Raised Perigee Orbit 375 km Perigee Orbit 750 km Perigee Orbit 250 km Perigee Orbit Epoch1/1/ :00 Apogee Altitude (km)33743 (L=6.3)32835 (L=6.1)32435 (L=6.1)35950 (L=6.6) Perigee Altitude (km)6627 (L=2.04)375 (L=1.06)750 (L=1.12)250 (L=1.04) Semi-Major Axis (km) Eccentricity Inclination (°)7777 Argument of Perigee (°)0000 RAAN (°)270 True Anomaly (°)0000 Period (hrs) (2 orbits/day) 9.63 (5 orbits/2 days) 9.62 (5 orbits/2 days) (7 orbits/3 days)

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.

ULTIMA Magnetometers (as of 2006)

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.

7.96 hr period (3orbit/day) Apogee 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 Magnetic Footprints along the 3 petal orbit (plot shows 20 orbits)

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

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

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

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

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

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

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.

Radiation Dose over 2 years Al, m m New orbit Apogee 4.24Re Perigee 750 km Raised perigee375 km perigee750 km perigee250 km perigee CRRES ELE/ PRO max dose AE-8/AP-8 max dose CRRES ELE/ PRO max dose AE-8/AP-8 max dose CRRES ELE/ PRO max dose AE-8/AP-8 max dose CRRES ELE/ PRO max dose AE-8/AP-8 max dose CRRES ELE/ PRO max dose AE-8/AP-8 max dose E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E+03

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

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.

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 km and the 8hrs period is maintained. The TID and worst case particle flux are not affected. Orbit maintenance is needed at 375 km.

Data still available from the Japanese meridian stations u.ac.jp/denji/obs/cpmn/statio n/map/russia.gif

L-shell Coverage ER ORBITALS Orbit Analysis DRAFT May (3) Orbit OptionsLow Earth Orbit Spatial Coverage h < 0.5R e (% of Time) Inner Zone Spatial Coverage 0.5R e < h < 1.5R e (% of Time) Slot Region Spatial Coverage 1.5R e < h < 3.0R e (% of Time) Outer Zone Spatial Coverage 3.0R e < h < 6.0R e (% of Time) Raised Perigee Orbit km Perigee Orbit with Orbit Maint km Perigee Orbit without Orbit Maint km Perigee Orbit km Perigee Orbit

Meridian Location Good Conjunction (ΔLong. < 15°) Very Good Conjunction (ΔLong. < 10°) Excellent Conjunction (ΔLong. < 5°) Churchill (94°W) Alberta Line (110°W) Europe (20°E)000 Japan (138°E)000 Churchill (94°W) Alberta Line (110°W) Europe (20°E) Japan (138°E)000 Churchill (94°W) Alberta Line (110°W) Europe (20°E) Japan (138°E) Churchill (94°W) Alberta Line (110°W) Europe (20°E) Japan (138°E)000 Churchill (94°W) Alberta Line (110°W) Europe (20°E) Japan (138°E) km Perigee 750 km Perigee 375 km Perigee No main Raised Perigee 375 km Perigee main ER ORBITALS Orbit Analysis DRAFT May Raised perigee typically >30% more conjunctions with the Churchill and Alberta line than lower perigee orbits.

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