Trident – a Mission to Triton

Trident – A mission to Triton

Dr. Carly J.A. Howett (SwRI) Drs. K.L. Mitchell (JPL) and L. Prockter (APL) The Trident Team Trident: An ambitious Discovery 2019 proposal to 30 AU Returning to Triton one season after Voyager 2

• Solar System’s 7th largest moon & largest KBO • Capture into inclined retrograde orbit likely catastrophic (e.g. McKinnon, 1984) • Extreme obliquity tides → ocean (Nimmo & Spencer, 2015)? Trident: An ambitious Discovery 2019 proposal to 30 AU

• With only 29 images and no compositional spectroscopy, Triton is: • The largest unmapped surface in the Solar System • Challenging to interpret with most feature types of unknown or disputed origin • Trident will perform multiple science investigations, including ocean detection, determining ionosphere origin, detailed IR/visible mapping and resolving plume origins … Voyager observed the ﬁrst ever plumes on an icy world

• Voyager 2’s camera observed multiple plumes, 2-4 compelling • ~8 km tall dark columns • 100s of km long streaks • Associated shadows • Close association with bright south Triton orbit polar terrain • Tear-shaped, dark “fan” deposits Planetary Cryovolcanism

Mars Enceladus Triton Cryovolcanism: Galileo showed us that Material CO2 H2O N2? cryovolcanism was less ubiquitous on icy Mass flux 0.15 kg/s 300 kg/s (total) 400 kg/s worlds than thought post-Voyager Duration <2 hours Sustained? Unknown

Pluto: An older surface, dominated by craters, plus surface- atmosphere exchange processes, has a similar atmosphere and volatile deposits. If plumes or fans were seen on seasonal caps, Triton plumes would be considered solved. No seasonal caps + no plumes or fans = inconclusive.

Mars: Solar- Enceladus: Ceres: Ahuna Mons, the young driven jets on H2O Jets sampling a dome on an old dwarf planet seasonal potentially habitable ocean CO2 caps Charon: Finally! Effusive NH3-H2O cryovolcanism? Mission Timeliness

• Triton’s 2038 flyby will obtain new imagery, of the unexplored anti-Neptune hemisphere at ~100 m/ px and revisit the sub-Neptune hemisphere obtaining Voyager-like quality images (~2 km/px). • SSG prediction: Migrated plume and fan locations will drift north on the south polar terrain • Cryovolcanism prediction: Sustained activity at previous sites more likely. Mission Design Consideration

Ballistic trajectory with no deterministic maneuvers Cruise • The baseline trajectory is ballistic from launch to the Triton flyby. Remote sensing instruments tuned for long-range observations give excellent opportunities. • Jupiter system encounter presents opportunities, but there are challenges due to radiation. • Small changes to the nominal trajectory prior to the Triton flyby can causes large growth in Δ�. • Post Triton Flyby, KBOs can be targeted with little Δ� by changing the Triton flyby date/time, but keeping the orbit geometry the same. Encounter List Several opportunities for outstanding bonus science

• Given current baseline trajectory:

BODY Date of C/A (ET) C/A Range (km) Diameter (km) NAC px (km) JUPITER-SYSTEM Metis 6/27/32 12:03 68,298 40 0.137 Callisto 6/27/32 14:39 685,595 4,821 1.371 Adrastea 6/28/32 0:53 219,767 20 0.44 Ganymede 6/28/32 2:36 659,982 5,268 1.32 Europa 6/28/32 6:47 485,336 3,122 0.971 Thebe 6/28/32 10:42 288,277 100 0.577

Io 6/28/32 15:37 15,587 3,643 0.031 NEPTUNE MOONS Nereid 9/28/38 15:29 4,861,030 340 9.722 Proteus 9/28/38 21:21 63,953 420 0.128 KBOS e.g. 2006 QL181 2001 2/11/41 20:29 64,274,844 154 128.55

• All of these timings are subject to change • Centaur, Comet, TNO and KBO encounter opportunities are being actively investigated by the team Comets

• List of closest approach with comets the Solar System Dynamics (SSD) website

Spice Body Name Date of C/A C/A Range BodySpice ID Body Name Date(ET) of C/A C/A(km) Range Body1000181 ID D/1993 F2-A (Shoemaker-Levy 9) 14-JUL-2032 (ET)11:54:42.4838 ET 1,348,930(km) 10001811000378 D/1993152P/Helin-Lawrence F2-A (Shoemaker-Levy 9) 14-JUL-203214-OCT-2031 11:54:42.483808:40:08.2166 ET 1,348,9307,641,049 10003781000271 152P/Helin-LawrenceP/1999 RO28 (LONEOS) 14-OCT-203123-JUL-2031 08:40:08.216607:01:23.9925 ET 17,806,786 7,641,049 10002711003007 P/1999335P/Gibbs RO28 (LONEOS) 23-JUL-203119-OCT-2032 07:01:23.992523:48:39.0381 ET 17,806,78627,011,107 10030071000703 335P/GibbsD/1766 G1 (Helfenzrieder) 19-OCT-203217-APR-2027 23:48:39.038118:35:34.5931 ET 27,011,10729,835,999 10007031003263 D/1766364P/PANSTARRS G1 (Helfenzrieder) 17-APR-202727-MAR-2028 18:35:34.593115:44:49.2444 ET 29,835,99930,864,423 10032631001656 364P/PANSTARRS169P/NEAT 27-MAR-202823-JAN-2031 15:44:49.244416:50:46.4140 ET 30,864,42332,270,896 10016561000337 169P/NEATP/2001 H5 (NEAT) 23-JAN-203114-OCT-2032 16:50:46.414020:29:59.5433 ET 32,270,89634,408,351 10003371000508 P/2001320P/McNaught H5 (NEAT) 14-OCT-203225-MAY-2026 20:29:59.543317:18:48.9615 ET 34,408,35134,531,227 1000508 320P/McNaught 25-MAY-2026 17:18:48.9615 ET 34,531,227 Centaurs

• Initial recon: Even distant data improves knowledge, but maybe increments w.r.t. JWST. • No good “deterministic” targets. Currently ~500 known, but probably only ~1% have been mapped. More opportunities likely for distant, disk-resolved observations. • No spatially-resolved IR Spectroscopy available. • Well-documented red-blue spectrum of surface colors. • Likely surface organics, so >2.5 μm particularly useful.

Current Trajectory All bodies in search Body ID Body Name Date of C/A C/A Range C/A Range C/A < 1 AU (ET) (km) (AU) 3531654 2010 BV62 11/18/32 66,827,592 0.4467 3721165 2015 KJ153 9/4/31 72,502,034 0.4846 3600676 2011 WA24 4/27/29 72,782,123 0.4865 3633713 2013 EN69 3/14/33 72,905,355 0.4873 3628995 2013 DK 3/24/33 80,287,079 0.5367 3667711 2013 CT160 12/30/32 102,436,540 0.6847 3740746 2016 AM67 3/1/33 114,331,995 0.7643 2389820 2011 WU92 1/30/34 126,528,801 0.8458 3794672 2014 EX156 5/10/33 126,634,275 0.8465 TNOs

• Initial recon: TNO encounters are feasible. • Currently ~1000 known TNOs, but probably only ~1% mapped. More options will open up. • New Horizons proof-of-concept: Arrokoth, type “cubewano (cold)” contact binary. • New Horizons data limited in spatial resolution and spectral range. • Like Centaurs, populations vary from blue to red colors. • Likely surface organics, so >2.5 μm particularly useful.

• Trident proof-of-concept: 2006 QL181. • Cubewano (cold) type (~150 km), like Arrokoth (30-45 km diameter). • 64,000,000 km encounter in Feb 2041, near 40 AU (14.5-yr after launch). • Delay to Triton encounter (~70 m/s delta-v) enables targeted 10000 km ﬂyby.

Spice Body Name Date of C/A C/A Range C/A Range Current Trajectory Body ID (ET) (km) (AU) All bodies in search 3378785 2006 QL181 11-FEB-2041 20:29:38.6107 ET 64274844 0.430 3092431 2001 QO297 26-JUL-2041 07:16:02.6433 ET 172917021 1.156 3092452 2001 QQ322 24-JUN-2041 07:47:28.7280 ET 179586242 1.201 3160763 2003 QT91 21-OCT-2041 18:58:38.8250 ET 214024551 1.431 3830984 2015 RX277 18-SEP-2041 07:05:25.9089 ET 220044023 1.471 3835620 2015 RL279 15-SEP-2041 03:14:30.8896 ET 280647709 1.876 3835655 2015 RT280 09-NOV-2041 09:55:10.2248 ET 283092293 1.892 3255350 2004 PC112 13-SEP-2041 03:03:56.7132 ET 298301961 1.994 Conclusions

• Trident represents an exciting opportunity to explore Neptune’s captured KBO Triton • Multiple opportunities for Centaur, TNO and Comet ﬂybys are possible • We are still working on the exact details!