Juno MCR-117198 Change Science Orbit Period to 14 Days …lasp.colorado.edu/home/mop/files/2015/02/MCR-117198.pdf5/6/2015 Stuart Stephens Juno Project Supplemental info for MCR-117198

Jet Propulsion Laboratory!California Institute of Technology!

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Supplemental info for MCR-117198:

Change Science Orbit Period from 11 Days to 14 Days

Juno Project

Stuart Stephens Mission Engineer

6 May 2015


2 5/6/2015 Stuart Stephens Juno Project

Supplemental info for MCR-117198 Change Science Orbit Period from 11 Days to 14 Days

Contents

•  Geometry data, and reference trajectory summary •  Solar conjunction in Activity Period 28 •  Overview of 14-day orbits •  DSN coverage and downlink capability •  Maneuvers: PRM, OTMs, Backup OTMs, and Deorbit •  Planetary protection and other Nav updates •  Attitude plan, and departures from Earth-point •  Power and thermal •  Other geometry, or other requirements associated with a typical science orbit •  Radiation •  For additional material, see summaries of orbit trade study and current trajectory




Geometry data, and reference trajectory summary [1/2]

•  Geometry data for 14-day orbits are available: –  Nav trajectory file, with summary comments, is in DocuShare Collection 193804:

•  spk_ref_150326_180221_150326.bsp –  Data at perijoves, apojoves, N/S poles, and equator crossings are at DS 180250:

•  Juno_Orbital_Data_Useful_for_Science_Planning_150413.xlsx –  Geometry data tabulated daily and every 10 minutes are at DS 121158:

•  Juno_Geometry_Data_for_150326_Ref_Traj_as_of_150413.xlsx •  Reference trajectory summary (from Juno_150326_ref_update_v4.pptx, presented at

4/1/15 Mission Planning meeting – see DS 193885), including updates wrt trade study: –  PJ1 longitude = 97.00° W (was 98.80° W). –  Deterministic JOI cleanup OTM now included to target longitude and orbital radius at

PJ1 (JOI cleanup OTM was previously purely statistical), with ΔV = 1.85 m/s. –  PJ1 altitude controlled such that perijove altitude remains below 7950 km at EOM

(altitude was previously maintained below 8000 km via PJ30+4d OTM). –  PJ4 shifted to delay repeat of PJ1 longitude until PJ31 (previously, PJ1 longitude was

most closely repeated at PJ18). –  Perijove times are now approximately 15 minutes earlier than previous delivery. –  Trajectory now includes only one extra orbit and impacts at PJ37 (was PJ38).




Geometry data, and reference trajectory summary [2/2]

•  14-day science orbits use 32 orbits to build up a complete grid: –  90° spacing after 4 science orbits (PJ4-7) –  45° spacing after 8 science orbits (through PJ11) –  22.5° spacing after 16 science orbits (through PJ19) –  11.25° spacing after 32 science orbits (through PJ35)

•  This is accomplished using 7 longitude shifts (generally associated with larger OTMs). •  See Nav materials accompanying presentations at orbital trade study reviews as well

as Mission Planning meetings on 3/10/15 (DS 192652) and 4/1/15 (DS 193885).




•  For geometric data, see geometry data files listed earlier •  For the trajectory with 14-day orbits, there is a solar conjunction in Activity Period 28, on:

–  10/26/2017 22:02 UTC (DOY 299). –  Minimum SEP = 0.93°. –  SEP ≤ 3° (likely downlink moratorium) = 10/23 06:08 to 10/30 11:45 (~7.2 days). –  SEP ≤ 2° (likely uplink moratorium) = 10/24 15:41 to 10/29 03:36 (~4.5 days). –  For reference, AJ28 is 10/24 20:03, and PJ29 is 10/31 19:33. –  For 11-day orbits, solar conjunction occurred sson after planned EOM on 10/16/2017.

•  See downlink capability summary (and effect of solar conjunction in AP28) on slide 12.

Solar conjunction in Activity Period 28




Overview of 14-day orbits [1/4]

•  Orbital trajectory (Mission Plan Figure 15-1):





•  Geometry and Activity Period templates for MWR AP4 and GRAV AP5 (shown individually on next 2 slides):





•  Geometry and Activity Period template for MWR AP4 (Mission Plan Figure 15-10):





•  Geometry and Activity Period template for GRAV AP5 (Mission Plan Figure 15-12):




•  Template for science orbits DSN coverage (Mission Plan Table 15-2):

DSN coverage and downlink capability [1/3]




•  An orbital downlink capability spreadsheet, based on this DSN coverage, is available at DS 175400: Juno_Orbital_Downlink_Capability_150410.xlsx





•  Resulting downlink data volume capability (total and science) per Activity Period:





•  Capture Orbits: –  07/05/16 02:30:00 UTC (02:31:08 ET) = JOI (at PJ0) –  07/13/16 17:58:52 UTC (18:00:00 ET) = JOI cleanup OTM (at PJ0+8.6d) –  07/27/16 17:58:52 UTC (18:00:00 ET) = AJ0 OTM (at PJ0+22.6d or AJ0-4d) –  09/10/16 17:58:52 UTC (18:00:00 ET) = PJ1+14d OTM –  10/19/16 18:00:00 UTC (18:01:08 ET) = PRM (at PJ2)

•  The Nav team has fixed JOI and PRM at Ephemeris Times that give familiar round numbers for UTC (02:30 and 18:00 UTC). These times are valid following the leap second that we know will be added on 7/1/15 (ET = UTC + 68.184 seconds), but they will change if one or more additional leap seconds is added before JOI or PRM. –  UTC times for JOI or PRM will move earlier by 1 or more seconds if this occurs.

•  OTMs – see see slide 14. •  Backup OTMs – see slide 15. •  Deorbit maneuver – assumed by Nav at 02/13/18 12:36:04 UTC in the reference

trajectory, 30 seconds before AJ36. •  For a maneuver ∆V summary, see Juno_150326_ref_update_v4.pptx (presented at

4/1/15 Mission Planning meeting – see DS 193885), or orbital data file (DS 180250)

Maneuvers: Capture Orbit, OTMs, Backup OTMs, and Deorbit [1/3]




•  OTMs have new times (decided at 3/10/15 Mission Planning meeting – see DS 192652), some of which are related to the 14-day orbit change: –  Previous baseline had all OTMs at PJ+4h, but MCRs 116311 and 116716 delayed

them to allow more time for south polar auroral science, especially in MWR orbits. –  MWR orbits – OTMs 4, 6, 7, 9 and 14 = PJ+7.5h. –  MWR Tilt orbit – OTM 8 = PJ+4h (largest OTM, and less important for JIRAM). –  GRAV orbits – OTMs 5, 10-13, and 15-35 = PJ+6h, mostly, except ...

•  GRAV orbits with larger OTMs – OTMs 12, 15-16, 19-20, and 26 = PJ+4h. •  Nav recommended keeping at PJ+4h all OTMs that would otherwise have ∆V 99% > 4.5 m/s at PJ+6h.

•  OTM 4 is an exception due to its importance following the first MWR perijove.





•  Backup OTMs now have 2 opportunities – PJ+4d and PJ+6d DSN tracks (see slide 10): –  PJ+4d is the default, for larger maneuvers (∆V would be even higher if done later). –  However, beyond a certain size, ∆V 99% > 25 m/s, we would not do a backup OTM. –  PJ+6d could be used for smaller maneuvers, at minimal ∆V cost, to afford a more

relaxed development schedule. –  Strategy would be decided in advance.





•  For preliminary planetary protection analysis for 14-day orbits that was provided to Cassie Conley in February 2015, see DS 195370.

•  Nav will be updating sections of the Navigation Plan as needed for the 14-day orbits.

Planetary protection and other Nav updates




•  C-kernel for reference trajectory with 14-day orbits is on the NAIF public site: –  http://naif.jpl.nasa.gov/pub/naif/JUNO/misc/nomck150410/

•  Attitudes were specified as follows (continued on next slide):

Attitude plan, and departures from Earth-point [1/2]




•  Attitudes were specified as follows (continued from previous slide):

Attitude plan, and departures from Earth-point [2/2]




•  Ed suggested at the 9/29/14 STM that I include a bullet/warning about power availability: –  I know we've said it several times during the week, but it bears emphasizing again in

this forum. I don't think we want to constrain the planning this early but perhaps there is an SPWG discussion about priorities and where they might cut back if we find we have a power problem.

•  Also note thermal considerations, since we plan to have MWR on near perijove. I.e., MWR has thermal stability requirements. The L2 requirements read (paraphrasing) ... –  Turn on MWR ≥ 10h before any required MWR science or cal (L2-PS-915) –  Keep MWR power on in each MWR orbit from ≤ PJ-120h to ≥ PJ+12h (L2-PS-910) –  Ensure MWR radiometer temperature varies ≤ 1 K in PJ±1h (L2-PS-773) –  Ensure MWR radiometer T varies ≤ 0.1 K for any 5-min interval in PJ±1h (L2-PS-991)

Power and thermal




•  See material generated for AP4 and AP5, and the two spreadsheets referred to in slide 3.

Other geometry, or other requirements associated with a typical science orbit




Radiation

•  Comparing total radiation dose for our current trajectory and for 11-day orbits (including final pre-impact PJ), we see the cost for PJ1 and two additional orbits is relatively small:

•  In addition, Heidi Becker and Virgil Adumitroaie updated Juno Radiation Environment model predictions for the 150326 reference trajectory at DS 181290 (energy and proton particle spectra, at 60-second resolution, from PJ-24h to PJ+8h for all orbits).




For additional material, see summaries of orbit trade study and current trajectory

•  DS 180884 for 8/13/14 Mission Planning meeting (IOT reports on trajectory options) •  DS 179635 for 12/18/14 NASA IRT external review, and earlier discussions •  DS 192652 for 3/10/15 Mission Planning meeting (to discuss trajectory for 14d orbits) •  DS 193885 for 4/1/15 Mission Planning meeting (to discuss trajectory and MP products) •  Magnetospheres of the Outer Planets site (MWG polar plots for 14d orbits)




Backup




Candy’s nomenclature graphic updated for 14-day orbits

•  For reference:




Two 53.5-day capture orbits with PJ1 (updated to show 14-day science orbits)

1st 53.5-day orbit (actually 53.419 days) 2nd 53.5-day orbit (actually 53.222 days)

AJ0 7/31/16 19:42

AJ1 9/23/16 03:44

PJ0 = 7/5/16 02:48 (JOI starts 02:30)

PJ2 = 10/19/16 18:11 (PRM starts 18:00)

PJ1 = 8/27/16 12:51

(all 3 PJs)

PJ0+1d PJ0+2d PJ0+3d

PJ0+10d PJ0+20d

PJ0+30d

PJ0+40d PJ0+50d ~ PJ1-3.4d

All tick marks are every 1 day from PJ0

All times are UTC

Solar conjunction (9/26/16 21:42)

JPE = 90° (9/7/16 01:08 ~ PJ0+64d)

JOI cleanup, PJ0+8.6d (7/13/16 17:59)

AJ0 OTM (7/27/16 17:59)

PJ1+14d OTM (9/10/16 17:59)

Approximate start of JOI critical sequence Instruments off JOI-5d

Instruments on JOI+50h

Instruments off PRM-5d

Earth-to-Jupiter View (Jupiter North Pole Up)




Orbital data useful for science planning [1/7]

•  Juno_Orbital_Data_Useful_for_Science_Planning_150413.xlsx [DS 180250]:


































Capture orbits and science orbits for previous baseline

•  Summary: Baseline mission is 30 science orbits (3-32). An extra orbit (33) is a spare.




Science orbit templates for previous baseline [1/2]

•  MWR activity period template (Activity Periods 3 and 5-8) – e.g., AP3:

–  PJ pass for MWR and other perijove science (6h, DSS-25, with MGA, no playback). –  PJ+4h pass for OTM (2.5h, 70-m track, with MGA, no playback). –  PJ+1d and PJ+2d downlink passes (8h, 70-m tracks, first return of PJ science data). –  PJ+4d downlink pass (8h, 70-m track, including backup OTM opportunity). –  PJ+5d downlink pass (10h, two 70-m tracks). –  PJ-3d downlink pass (4h, 70-m track). –  PJ-1d downlink passes (8h, two 70-m tracks, including for next OTM uplink).




•  Gravity Science activity period template (Activity Periods 4 and 9-32) – e.g., AP4:

–  PJ downlink pass for GRAV and other perijove science (8h, DSS-25, Earth-pointed). –  PJ+4h pass for OTM (2.5h, 70-m track, with MGA, no playback). –  PJ+2d downlink passes (8h, 70-m track, first return of PJ pass data). –  PJ+4d downlink pass (8h, 70-m track, including backup OTM opportunity). –  PJ+5d downlink pass (10h, two 70-m tracks). –  PJ-3d downlink pass (4h, 70-m track). –  PJ-1d downlink passes (8h, two 70-m tracks, including for next OTM uplink).

Science orbit templates for previous baseline [2/2]

Documents

Juno MCR-117198 Change Science Orbit Period to 14 Days …lasp.colorado.edu/home/mop/files/2015/02/MCR-117198.pdf5/6/2015 Stuart Stephens Juno Project Supplemental info for MCR-117198