Neptune: the gateway to the Kuiper Belt Innovative Mission Concept Argo for New Frontiers 04 • Fly by a Trojan (no Jupiter GA) or Jupiter • Gravity assist from Saturn Voyage Through the • Fly by Neptune/Triton system Outer Solar System • Fly by a scientifically-selected Kuiper Belt Object Key Characteristics Candice Hansen (JPL) • Focused science mission Heidi B. Hammel (Space Science Institute) • Simple mission profile • Current instrument technology (NH) with Don Banfield (Cornell), Amanda Hendrix (JPL), Krishan Khurana (UCLA), Damon Landau (JPL), • Current spacecraft technology (NH) Alfred McEwen (U. Arizona), Linda Spilker (JPL), • Capable payload Tom Spilker (JPL), John Stansberry (U. Arizona), Ed Stone (Caltech) , Nathan Strange (JPL) • Radioisotope power Argo and Decadal Priorities Argo and Decadal Priorities NOSSE Report: "Opening New Frontiers in Space: Choices for the Next New Frontiers Announcement of Opportunity" • Planetary Decadal Survey also explicitly mentions In order for the New Frontiers Program to remain healthy over the long run, Neptune/Triton in multiple chapters it must maintain an influx of new ideas and grow the applicant pool for new missions. – Giant Planets, Large Satellites, Primitive Bodies Selected New A. Kuiper Belt – Pluto Explorer Innovative Mission Concepts • Neptune in far future because Flagship-class orbiter assumed B. Jupiter! Polar Orbiter with Probes • mission options outside the 3 remaining and 5 additional medium-sized! decadal 1975 1985 1995 2005 Three Remaining missions 1. South Pole-Aitkin Basin Sample Return Voyager 1 Cassini Pioneer 11 2. Venus In Situ Explorer • spurred by major scientific and Voyager 2 Orbiter technological developments made since 3. Comet Surface Sample Return the decadal survey! Five Additional • offer potential to dramatically advance fundamental scientific goals of the 4. Mars Network Science Pioneer 10 Voyager 1 Galileo New ! Cassini 5. Trojan/Centaur Reconnaissance decadal survey Pioneer 11Voyager 2 Orbiter Horizons 6. Asteroid! Rover/Sample Return • accomplish scientific investigations well 7. Io Observer beyond! the scope of the Discovery 8. Ganymede Observer != Argo program Argo Neptune Flyby is Crucial Access to Kuiper Belt Objects Argo’s accessible KB volume is ~4000x that of New Horizons The Neptune flyby enables the opportunity to: New Horizons cone of accessibility, Kuiper Belt Objects without propulsive assistance, visit a Trojan would be 1/4 the diameter of the period at the end of this swing past Saturn sentence. fly by Neptune/Triton New Horizons, ~0.9° with propulsive assistance AND continue on to a KBO Carolyn Collins Petersen, and Richard Wright for Gemini Observatory Argo without Potentially in the Argo cone: propulsive assistance ~60° The Neptune flyby also 18 Cold Classical KBOs permits selection of the 40 KBOs with 200 < D < 400 km Neptune-to-KBO flight times 9 KBOs with D > 400 km (large KBOS) Neptune are ~1.5-3 years KBO with highest scientific interest Graphic created by Mark Petersen, several binary KBOs (KBO at 35-39 AU) Compelling Neptune science Argo Science Opportunities • Planetary System Architecture Fundamental New Science – Exoplanet population increasing – Comparative planetology of multiple KBOs: Pluto (large in situ), NH's KBO, dramatically Argo's Triton (captured), Argo's KBO (scientifically-selected) • Growing number of – First surface geology of a Trojan ice-giant-mass objects – First detailed images of Neptune's atmosphere in a new season • Pushing towards U/N equivalent – First detailed images of Triton's atmosphere after significant change distances in near future – First measurement of stability of an offset/tilted magnetic field – Microlensing – Near-IR radial velocity – First detailed images of Neptune's ring system in new dynamical state – Knowledge of local ice giants Incremental Science Engages a significant fraction of extremely limited – Ice giant interior measurements the planetary community • Earth-based efforts extraordinarily challenging compared to J & S – Small satellite science – Ice giants smaller – Ice giants much more distant Significant small icy body science as per decadal objectives – Ice giants colder Adapted from the ExoPlanet Task Force Presentation to the AAS, Austin, TX (Jan 2008) Progress on decadal Neptune science objectives – No currently planned mission to Neptune until an orbiter >2045 Sets the stage for a future Neptune System Flagship Orbiter Argo will set the stage for a future orbiter Achievable within New Frontiers resources Why New Frontiers 04? Argo Launch Windows for Fast Flights • Preliminary • Launch options between 2017 and 2020 – Such windows occur every 12 years due to giant-planet gravity assist • Searched 2013-2027 • Two criteria • Neptune flagship orbiter precludes a KBO flyby (and likely no Trojan) V! <17 km/sec at Neptune arrival Time of Flight <10 yrs • Fills in the >50-year observational gap of a dynamic system – Will enable linking of future flagship to past flyby Both criteria met – The season has already changed on Neptune (solstice was 2005) Criteria not met – Loss of expertise from Voyager-era scientists from the 1989 Neptune flyby FF launch window ~2 yrs long The next window opens in 2027 • Exoplanetary Neptunes are now known to exist – Knowledge of local ice giants is substantially less than gas giants Mission Trip Time V! (km/sec) Argo w/ JGA 8-10 yrs 12 - 16 Voyager 12 yrs 17 New Horizons 9.5 yrs 14 Outer Solar System Exploration: Current Plan Sample Trojan-Triton-KBO trajectories 2005 2015 2025 2035 New Horizons Neptune Flagship? Cassini Orbiter A531/Bi-prop = 755 kg (delivered mass at KBO) A531/Bi-prop = 720 kg (delivered mass at KBO) Trojan: 2001 TW148, D ~ 20 km Trojan: Deikoon, D ~ 50 km Juno OP Triton: flyby alt 500 km at V = 13 km/s Trojan/Centaur Flyby? ! Triton: flyby alt 735 km at V! = 13 km/s Orbiter Flagship KBO: 2001 QX297, D ~ 150–350 km KBO: 2005 TB190, D ~ 250–600 km Cold Classical Large KBO Trojan trajectories increase flight time, e.g., from 10 yrs to 13+ yrs Outer Solar System Exploration with Argo 2005 2015 2025 2035 New Horizons KBO Flyby 2038 Neptune/Triton Neptune Flyby 2032 Flagship? BACK UP CHARTS Argo NF04 Cassini Orbiter Saturn Flyby 2024 Juno OP Trojan Flyby 2023 Orbiter Flagship or !!!!!Jupiter Flyby 2023 Argo dates notional - still under study Of $1B Boxes and Bricks Argo Mission Concept Team “I heard that a joint NASA study by JPL and APL said NASA couldn’t send any mission to the outer Solar System for less than $1B.” This is wrong. • Principal Investigator (PI): Candice Hansen, Triton science The “Titan and Enceladus $1B Mission Feasibility Study” actually said: Pg 1-1: “no missions to Titan or Enceladus that achieve at least a moderate understanding • Deputy PI: Heidi Hammel, Neptune science beyond Cassini-Huygens were found to fit within the cost cap of 1 billion dollars (FY’06).” Relevance to Neptune: None • Project Scientist: Linda Spilker, ring science • Senior Science Advisor: Ed Stone “But I also heard that the study said NASA couldn’t even send a BRICK • Co-Investigator: John Stansberry, KBO science (spacecraft with no instruments) to the outer Solar System for less than $800M.” This is only partially correct. • Co-Investigator: Krishan Khurana, magnetospheric science CORRECT Pg 1-11: “Even the lowest cost mission studied [Enceladus flyby], without the cost of science payload, has a minimum expected cost of ~$800M.” • Mission Architect: Tom Spilker HOWEVER Pg 2-4: “[The Enceladus flyby’s] design (and therefore cost) was uniquely derived using actual cost data from the NH mission.” • Trajectory Design: Nathan Strange Neptune cost mitigators: Can use an Atlas 541 instead of a 551. Do not require Star-48 upper stage. Other savings under study. • Instrument Leads: Alfred McEwen, Don Banfield, Amanda Result: $$ available for Argo science payload within $800M cap Hendrix Past, Present, and Future of Outer Solar System Exploration Argo Science Objectives 1975 1985 1995 2005 2015 2025 2035 New Horizons Nearly all aspects of the Neptune system detectable from Earth have changed significantly since Voyager fly-by in 1989 Voyager 2 • Neptune's atmosphere shows fundamental differences in large- Voyager 2 scale structure – No Vgr GDS, significant atmospheric evolution on <5-yr timescale; evidence Voyager 1 Cassini for stratospheric heating since Voyager Pioneer 11 Voyager 2 Orbiter Neptune Measurement Goals – Small-scale cloud distribution – Atmospheric lightning – Magnetic field measurements in completely different Pioneer 10 Voyager 1 Galileo New Juno orientation Pioneer 11Voyager 2 Cassini OPF Orbiter Horizons Orbiter – First detailed compositional/spectral map – First detailed infrared map – Gravitational moments refined for interior models Argo Science Objectives Argo Science Objectives - Triton Nearly all aspects of the Neptune system detectable from Earth Map regions of Triton seen only from a distance by Voyager ("terra have changed significantly since Voyager fly-by in 1989 obscura") -- as well as more of Triton's northern hemisphere -- in order to extend the post-capture cratering history and reveal surface modification. Ring system science objectives (plus small satellites) • More of Triton's northern hemisphere will be sunlit – Most of it was in seasonal darkness for Voyager • The ring system has changed Terminator in 2027 Terra incognita – Arcs evolved within <8 yrs timeframe: 60° Terminator in 1989 VGR era: 45° • Neptune’s Magnetosphere – Very complex and Terra Terra undetectable from Earth obscura obscura Argo