Technologies for Outer Solar System Exploration

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1 Technologies for Outer Solar System Exploration Ralph L. McNutt, Jr. Johns Hopkins University Applied Physics Laboratory and Member, OPAG Steering Committee

2 Space Exploration has historically been aligned with an outward look and with humans as key players. but robotic, scientific exploration has ALWAYS come first PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 2

3 Technology development is never as easy as we initially think PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 3

4 The Devil is ALWAYS in the Details Say, I think I see where we went off. Isn t eight times seven fifty-six? PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 4

5 For Any Mission There Are Four Key Elements Science the case for going Technology the means to go Strategy all agree to go Programmatics money in place A well-thought-out systems approach incorporating all key elements is required to promote and accomplish a successful exploration plan PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 5

6 Answering the Science Questions is a System of Systems Problem DRIVERS Reach objective in a reasonable time Return data Operate reliably through end of mission Science Questions Mission Science Objectives Objective Questions Science Measurement Objectives Required Instruments Instrument Resources and Requirements Mission and Spacecraft Requirements Data Product Analysis Product Science Result PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 6

7 How Does Technology Fit In? Talk is cheap ( ) Flight qualified hardware is expensive ( $ ) New developments ARE research projects Research projects can hit dead ends -> need exit strategy Take time ( $$ ) Require skilled, motivated people - not plug-and-play personnel ( $$ ) Must be moved from lab to implementation ( $$$$ ) Enabling technology is just that - i.e. REQUIRED A robust infrastructure is necessary - but not sufficient - and largely invisible and expensive to maintain ( $$$$$ ) PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 7

8 Technologies for Outer Planet Missions Generic Spacecraft (onboard, primary) propulsion Spacecraft power Infrastructure Launch vehicle availability, cost, and characteristics Deep Space Network and upgrades Electronic parts availability and radiation tolerance Qualification of systems to decades-long missions Focused Extreme environments and mission specific PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 8

9 Technology Comes in Several Colors Enabling vs enhancing - mission specific Infrastructure Parts, testing, and qualifying NASA vs other customers - mission specific NASA Unique Multiple missions - generic Single missions - unique If enabling then a show stopper if un(der)funded Long-lead vs development after new start PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 9

10 Destinations: Where the Clues Are Drives a mix of technology requirements Giant gas planets Jupiter Saturn Ice giant planets Uranus Neptune Pluto and the Kuiper Belt Objects Small icy worlds Ganymede Callisto Enceladus Tethys Dione Ariel Intriguing moons Europa Titan Triton Io Miranda PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 10

11 Propulsion Issues for Robotic Missions Object Equatorial escape speed (km/s) Going to the outer solar system and into orbit Landing on any solid planet (Mercury through Pluto + minor bodies) - high thrust required What works for the Moon can work for all cases - most stressing is Ganymede of 2.74 km/s escape speed (versus 2.38 km/s for the Moon) [All cases includes Europa, Titan, Triton] Earth Venus Mars Mercury Moon PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 11

12 High Thrust Requires Thermal Rockets For a chemical biprop system I sp ~ 320s --> v exhaust = 3.1 km/s For a cryogenic biprop I sp ~ 420s --> v exhaust = 4.1 km/s For a nuclear thermal system I sp ~ 900s --> v exhaust = 8.8 km/s LH2 storage is an issue - being worked for VSE return to Moon LOX and CH 4 is a possibility - being worked for VSE ISRU Integrated systems studies are required All targets are also effectively vacuum environments - notable exception of Titan PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 12

13 Propulsion Systems Status I Chemical propulsion remains the primary propulsive means and is the only current high-thrust option Aerocapture - braking into planetary orbits - may be an alternative; requires a target atmosphere, good knowledge of the target atmosphere, and is yet to be demonstrated PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 13

14 Propulsion Systems Status II Large ΔV at low thrust can be enabling for multiple advanced exploration missions WE KNOW THE CHARACTERISTICS AND LIMITATIONS WITH GOOD ESTIMATES FOR SPECIFIC MASS Solar Electric Propulsion was tested with DS-1 and is being implemented on Dawn but is limited limited by need for solar arrays Nuclear Electric Propulsion was started under Project Prometheus and no longer being pursued. Radioisotope Electric Propulsion looks VERY promising but needs more development to get specific mass down Solar sails required in-space testing remains elusive PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 14

15 RPS Issues Specific power has reverted to lower values from he old RTG architecture (Cassini, Galileo, Ulysses) Outer planet missions, in general, cannot use solar arrays due to low solar illumination levels (Jupiter may be an exception depending on orbital tour) For some missions efficiencies above ~8 We/kg may be enabling due to mass constraints MMRTGs (current gen) are too heavy (< 4 W/kg) SRGs offer Pu savings - ideal solution at high specific mass if lifetime and EMI/EMC issues can be retired Current DOE plans (see Idaho National Larobratory website) are Consolidate production of Pu-238 at INL Production rate of 5 kg per year Operational plan calls for running from 2012 through 2047 (35 years) PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 15

16 Extreme Environment Spacecraft Radiation levels - high Pressure - high Temperature - low and high Must be Buildable and launchable in an Earth environment Testable at target environement ( test as you fly ) Survivable at target environment for mission duration PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 16

17 Strategic Roadmap for Solar System Exploration - Mission Set Options Used for Technology Requirement Audit NEEDS CANNOT BE ASSESSED WITHOUT EXAMPLE MISSIONS New Frontiers Kuiper Belt/Pluto Jupiter Polar Orbiter (Juno mission selected June 3, 2005) Lunar South Pole Aitken Basin Sample Return Comet Surface Sample Return Venus In Situ Explorer Jupiter Fly by with Probes (added by SRM team, May 22, 2005) Flagship Missions Decade 1 Europa Geophysical Orbiter Decade 2 Titan Explorer Venus Surface Explorer Decade 3 (one of four) Europa Astrobiology Lander Neptune Orbiter with Probes Comet Cryo Nucleus Sample Return Venus Sample Return Discovery missions implemented 5 times a decade are also an integral part of the Strategic Road Map plan PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 17

18 From: SRM 3 The Solar System Exploration Strategic Roadmap Two areas of technology development have been identified as of the highest priority to enable the flagship mission concepts discussed here. These are radioisotope power sources and technologies for extreme environments including those characterized by high radiation, high and low temperature, extreme pressure, and the high heating rates encountered by atmospheric entry probes. In addition, technologies for ultrahigh bandwidth and ultra-high pressure (for deep atmospheric entry probes) communications warrant careful assessment, as do technologies for autonomous systems, in situ science instruments, nanotechnology, and advanced modeling. These and other areas of technology development, including advanced propulsion to shorten trip time to distant destinations in the outer solar system, are discussed in more detail below. PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 18

19 Implementation Desires Imply a Technology Development Timetable PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 19

20 Gas Giants - Technology Atmospheric probes Certain measurements can t be done any other way Always a need for entry probes Need for this technology will not go away Power not a major issue as long as RPS is available Thermal protection PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 20

21 Europa - Technology Mass and power will be tight - see next major bullet Need generic low-mass RPS MUST have programmatic sign-off for Earth flyby Radiation levels are Europa-mission specific Hardening of electronics and optics hardware ASIC and Actel hardening by implementation design Vault - throw mass at the problem Need ALL approaches to deal with levels A Lander will drive the technology needs even more No high-thrust propulsion system at Isp> ~320s is credible Cryo-lander needed - low mass Cryo-instruments needed - low mass These are also issues for Titan, Triton, and other targets - but without the radiation background Radiation is a significant technology driver PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 21

22 Small Bodies - Technology KBOs technology need: propulsion, power, propulsion (P 3 ) Up to 10 years cruise and 1 year orbit Multiple body flybys - a desirement for diversity (even more P 3!) Orbital mission to Centaur 6-8 years Centaur orbiter mission 1 year in orbit Low-mass, efficient RPS - generic Long lifetime parts qualification - generic Low(er) power, efficient ion engines - less generic but we are relatively close PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 22

23 Titan - Technology Efficient, low-mass RPS - enabling Orbiter/ delivery craft Aerobot/lander/rover Blimps and/or aerobots - enabling for significant terrain coverage [is this a REQUIREMENT?] Operation in extreme (cold) environments - cryogenic spacecraft - generic Upgraded DSN - enhancing Automomy - enabling - generic High bandwidth from data platform - likely enabling [but need REQUIREMENTS] Technology demonstration - needed for the platforms (demonstrations in relevant environements is a generic problem that tends to be mission specific) PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 23

24 Technology REQUIRED for CREDIBLE Outer Solar System Exploration Generic Technology Advanced high mass-to-power radioactive power sources (RPS) 2nd gen EMI-quiet Stirling Radioisotope Generator Advanced high-temperature RTG, e.g. skutterudite converters Autonomous systems (long one-way light time) Space-flight parts and subsystems qualified for long missions and environments - appropriate testing and validation for reasonable costs (!!) Infrastructure Cost-efficient, high-performance EELVs (current designs - maintain adequate inventories); are upper stage tweaks needed? DSN Ka-band antenna farm of massively phased array ( m antennas) Affordable DSN aperture time for the antenna farm PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 24

25 Example Assessment of a point design : Titan Organics Explorer 1 km Ziels Enabling Technologies Advanced RPS Aeroshell/Aerocapture + autonomous navigation Communications infrastructure (post-70m DSN) Cryogenic spacecraft ( extreme environments ) Airship - development and TEST - mission specific Mission specific miniaturized instruments (sample acquisition, manipulation, and analysis) PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 25

26 Technology, Programmatics, and Out-year Budgets are Intertwined Need to coordinate science and technology Review CONCENSUS mission concepts - prioritize the technologies Document position Need validations of priorities New Millennium validates flight technologies - choke point for all Need understanding of required mission architecture to feed into technology funding PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 26

27 Flagship Decision Criteria Decision Points are influenced by the confluence of 3 major factors: scientific priorities and knowledge technological readiness or capability, and programmatic considerations Precursor missions influence the destination(s), the campaign architecture, and the approach Discovery and New Frontiers missions selected can influence other priorities A focused investment in critical technologies and capabilities will enable the missions, and will dictate the timetable for their implementation. PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 27

28 Outer Planets Program 3 NF missions to the outer solar system/decade Discovery mission opportunities Telescopic observations Research and Analysis Technology development PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 28

29 OPAG (Self-)Goals for Technology Review the mission set for science content and priorities Develop, as needed, equivalent mission concepts to meet the science priorities Evaluate the mission concepts in terms of the operational scenarios (in situ, orbiter, both) Validate the key technologies required Prioritize the technologies, considering the mission priority and benefit trades of the technologies to the desired timeline for the mission start (What do you need in what order, and when do you want to launch) Document this position! PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 29

30 Top Technology Needs RPS - efficient, minimize 238 Pu needed Available launch vehicles for reasonable cost - better upper stages?? Up-scaled DSN at Ka-band - at reasonable aperture cost Space-qualified parts and reasonable qualification and test requirements Mission specifics begin to enter PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR RLM - 30