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Home , Argo (NASA spacecraft), Flyby (spaceflight), Juno (spacecraft), Magnetometer (Juno), Pioneer 11, Ralph (New Horizons)

Argo: New Frontiers 4 Mission Concept

A small body explorer doing exceptional science Argo - Fly by a Object; close of - Fly by - assist from and

Voyage Through Key Characteristics: Focused science mission the Outer Simple mission profile Current instrument technology Update Current technology Capable payload Nuclear power Candice Hansen (JPL) & Heidi B. Hammel (Space Science Institute)

Outline - Updates since last Past, Present, and Future of Outer Solar System Exploration OPAG meeting 1975 1985 1995 2005 2015 2025 2035

• Short review of concept w/ tightened science focus

– New Frontiers 4 Voyager 2 – New trajectory options

• Updates Cassini Voyager 2 – Spacecraft partner Orbiter Orbiter – Payload definition

Pioneer 10 Voyager 1 New Cassini • Decadal Survey Pioneer 11Voyager 2 Orbiter Horizons Orbiter Orbiter • OPAG request

1 Past, Present, and Future of Outer Solar System Exploration Neptune flyby enables KBO science 1975 1985 1995 2005 2015 2025 2035 New Horizons Argo - Kuiper Belt • to continue on to a KBO! Voyager 2 Argo - Neptune & Triton • Potential KBO Targets – Our cone of accessibility includes ~40 of Voyager 2 the largest KBOs – Several binary KBOs – Many objects in the cold classical disk Argo - Saturn GA Voyager 1 Cassini Titan

Pioneer 11 Observatory Gemini for Wright Richard and Petersen, Collins Carolyn Voyager 2 Orbiter Orbiter • Neptune flyby permits selection of KBO with highest scientific interest Argo - Jupiter GA Voyager 1 Galileo New Juno Europa

Cassini Petersen, Mark by created Graphic Pioneer 11Voyager 2 Orbiter Horizons Orbiter Flagship Address evolution of the solar system…

Access to Kuiper Belt Objects Argo Science Objectives - KBO

Argo’s accessible volume is ~4000x that of New Horizons • Reconnaissance of primitive solar system body that is Flight time to KBO is just ~1.5 - 3 years (KBO at 35-39 AU) member of a much larger population • Determine comparative properties of captured KBO Triton and a KBO in situ

• Expand the diversity of volatile-rich small bodies explored in the outer solar system New Horizons, – Between Argo and New Horizons ~0.9° with propulsive assistance (shown here) we will double the number of explored KBOs Argo without • Potentially in this cone: propulsive assistance ~60° • New Horizons in situ KBO 9 KBO’s with diameter > 400 km 40 KBO’s with 200 < diam < 400 km • Triton 18 cold classical KBO’s • Argo in situ KBO

2 Argo Science Objectives - Triton Argo Science Objectives - Triton

Triton Science Objective 1: Triton has a youthful surface, substantially Triton Science Objective 2: Triton’s climate is controlled by its modified when Triton was captured by Neptune. Argo will map the side of nitrogen atmosphere in vapor equilibrium with surface frost. Argo Triton seen only at a distance by Voyager (‘ obscura”) and more of the will map the distribution of ices on Triton’s surface and measure the northern hemisphere. Near-global surface coverage will extend the post- atmospheric pressure to capture another point in time for modelling capture cratering history and other modification of Triton’s surface. climate change on an icy body • More of Triton's northern hemisphere will be sunlit • Triton's atmosphere has changed significantly since the Voyager flyby in 1989 – Most of it was in seasonal darkness for Voyager – Nitrogen and ices move seasonally from hemisphere to hemisphere and the pressure of the Terminator Terra incognita in 2027: 60° atmosphere increases and decreases seasonally

Terminator in 1989 for VGR flyby: 45° Terra Terra obscura obscura Will Triton’s enigmatic plumes still be active?

Example 2019 Launch Options Why NF4? Voyager-like flight times to Jupiter and Saturn

• Launch opportunity window from 2017 - 2019 – Such windows occur every 12 years due to Jupiter • Waiting for flagship, or next window, will result in ~50- year gap in observations of a Triton dynamic system • Neptune / Triton Flyby is complementary to eventual Neptune system orbiter – Outstanding ice giant science can also be obtained on the way to the KBO • Need time to resolve nuclear power issues Time of Flight = 9.3 yr Time of Flight = 10.2 yr Neptune flyby 2028 Neptune flyby 2029 38S Neptune periapsis 21N Neptune periapsis KBO: 2005 PS21 KBO: 2001 QS 322

3 NF3 vs. NF4 NRC Midterm Report New Frontiers 3 New Frontiers 4 AO comes out 2008 • The Committee on Assessing the Solar Proposal writing, down-select 2009 System Exploration (CASSE) Program gave Step 2 = Phase A 2010 NASA a “C” in its 2008 Report, on Science Phase B 2011 Question #2*, and made the specific Phase C/D 2012 Phase C/D 2013 AO comes out 54 months after recommendation: NF3, write proposal – “The next solar system exploration decadal survey Phase C/D 2014 Down-select, Step 2 = Phase A should address the objectives and merit of a opens 2015 Phase B Neptune/Triton mission” Launch 2016 Phase C/D Launch backup 2017 Phase C/D Launch backup 2018 Phase C/D • NF4 can raise this grade without a flagship 2019 Launch in February 2020 Launch backup

* How long did it take the gas giant Jupiter to form, and how was the formation of the ice giants ( and Neptune) different from that of Jupiter and its gas giant sibling, The schedule for NF4 is tight but not out of the question Saturn?

Spacecraft Update Notional Argo Payload Preliminary suite based on science traceability matrix • Envisioned spacecraft is similar to New • High resolution visible camera - New Horizons (NH) or reduced Horizons spacecraft Cassini heritage - Alfred McEwen – Similar total mass and mass distributions • Near- spectrometer - NH heritage - Don Banfield (~400 kg dry mass) • UV solar & stellar occ. spectrometer - reduced Cassini heritage – Similar power needs (200 W) - Amanda Hendrix • Must use nuclear power • Far-infrared linear radiometer - Diviner heritage - David Paige • - Krishan Khurana • Spacecraft partner = • Charged particle spectrometer - McNutt Aerospace (LMA) • Gimballed high-gain antenna - heritage radio science instrument Beyond this: explore trade space for other instrumentation in terms of science, cost, power, and mass

4 Payload mass Argo science team KBO Triton Neptune Neptune Neptune Rings Magneto- sphere 8.6 kg Lorri J. C. H. L. Spilker K. Khurana Stansberry Hansen Hammel 10.5 Ralph High res A. McEwen M. Brown M. imager Showalter 5.0 UV Near IR D. Banfield imager 12.0 Diviner UV A. Hendrix Your J. Colwell spectrograph 10.0 Magnetometer w/ boom Far IR linear D. Paige A. Simon- radiometer NameMiller 3.5 Charged particle spectrometer Magnetomet K. Khurana M. er Here Dougherty 1.5 USO Charged R. McNutt particle 51.1 kg Total spectrometer Lead scientists recruited; plus other key members Most slots will stay open until we are ready to write the proposal

Motivation for Argo Decadal Survey Argo 2008 - 2011 Activities • Most important near-term goal is to be highly ranked in the new decadal survey • Previous Decadal Survey drove the – Panels to be formed in 2009 selections for New Frontiers 1, 2, and 3 – Report due to HQ 2010 – NF1: New Horizons – Launch window is 2011 - 2020 – NF2: Juno – NF3: No-nuclear mission constraint excludes all targets beyond Saturn • Argo science team activities for 2008, 2009 – White paper (~done) • Previous studies (e.g., two vision mission – Address SBAG, OPAG, PSS, Complex concepts) focused on Neptune orbiter, not on advantages of a flyby • Timing is urgent: when Argo is selected we will need – Scientific selection of a KBO can only happen with to hit the ground running because NF4 puts us at the flyby end of the good launch opportunity

5 Argo and New Frontiers Of $1B Boxes and Bricks

“I heard that a joint NASA study by JPL and APL said NASA couldn’t send any • Argo must fit within a New Frontiers mission to the outer Solar System for less than $1B.” This is wrong. budget The “Titan and $1B Mission Feasibility Study” actually said: Pg 1-1: “no missions to Titan or Enceladus that achieve at least a moderate understanding • Our most important challenge is to get a beyond Cassini- were found to fit within the cost cap of 1 billion dollars (FY’06).” good cost estimate as quickly as Relevance to Neptune: None possible “But I also heard that the study said NASA couldn’t even send a BRICK (spacecraft with no instruments) to the outer Solar System for less than • Advantage of early partnership with $800M.” This is only partially correct. LMA is key to scope the mission 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.” HOWEVER Pg 2-4: “[The Enceladus flyby’s] design (and therefore cost) • We need to do this now to support the was uniquely derived using actual cost data from the NH mission.” Decadal Survey Neptune cost mitigators: Can use an 541 instead of a 551. Do not require -48 upper stage. Other savings under study. Result: $$ available for Argo science payload within $800M cap

Cost-Saving Options Proposed Short-term Activities

• Use simple spacecraft with current (New Horizons) heritage A. Top Priority – Experience base and corporate knowledge available 1. Trajectory analyses – No miracle developments required • trades • Identify many trajectories, some of which offer mass relief • Triton and Neptune science vs. KBO accessibility – NH’s upper stage may not be needed 2. Power trades and plutonium availability • MMRTG vs. ASRG • Use smaller launch vehicle 3. Mission Cost – 541 instead of 551 -- promising for some trajectories • How to accomplish this mission with a New Frontiers budget • Scale instrument requirements to available $ • Team X session B. Additional work on mission design • Use the market-based approach that Cassini followed for payload development (power, mass, dollars were trade-able) 1. Assessment of spacecraft mass, power (from analogs) • No instruments over-ran or were descoped from payload 2. Evaluation of DSN requirements and onboard data storage 3. Trade study on how KBO selection affects spacecraft lifetime requirements • Science ops at Jupiter or Saturn will be a mission of opportunity – Under SALMON umbrella We will only get one shot at this proposal because the window will close

6 Argo Summary Request for OPAG Findings • A KBO encounter explores another primitive outer solar system body • We request OPAG’s endorsement for Argo as – Triton / KBO comparison important mission for outer (big and – Pluto / KBO comparison dwarf) exploration – Numerous potential targets • We request that OPAG keep the pressure on • Triton and Neptune are compelling flyby targets for the nuclear power situation to be solved – Dynamic worlds, rich opportunities for new science discoveries – Trajectories identified with reasonable trip times and approach velocities – A letter should be sent to the NRC Radioactive Power Supply committee stressing how essential • The Argo Mission is this is for exploration of the outer reaches of our feasible for New Frontiers solar system – Key science addressed by instrument package based on New Horizons heritage • We request that OPAG stress the importance – Avenues available for additional cost savings to HQ of keeping the communications in development, operations, and launch vehicle infrastructure intact for outer planet missions – Mission is scoped to be accomplished within New Frontiers cost cap (DSN 70 m stations)

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