Presentation on theme: "1 Lunar Atmosphere and Dust Environment Explorer (LADEE) Mission--a Report Tom Morgan LADEE Program Scientist NASA HQ."— Presentation transcript:
1 Lunar Atmosphere and Dust Environment Explorer (LADEE) Mission--a Report Tom Morgan LADEE Program Scientist NASA HQ
2 Lunar Atmosphere and Dust Environment Explorer (LADEE) Mission--a Report I. Background II. SDT III. Project Snapshot IV. Synergies with Artemis
3 Background The top eleven science goals identified in the National Research Councils report, Scientific Context for the Exploration of the Moon include: –(a) determine the global density, composition, and time variability of the fragile lunar atmosphere before it is perturbed by further human activity, and –(b) determine the size, charge, and spatial distribution of electrostatically transported dust grains and assess their likely effects on lunar exploration and lunar-based astronomy. The LADEE Mission was designed to address these objectives Identify a prioritized set of scientific goals that can be addressed in the near term (~2006-2018) by robotic lunar missions…
What What We Know Is There Looks Like From Potter and Morgan (1998) observations of the Na exosphere using a coronagraph--can be fit with a temperature of 1280 K, falling off with a cos 3 function of latitude. Model of the expected global distribution of Ar-40 at 30 km and 50 km [provided by D. Hodges]. Gas densities peak at the sunrise terminator, where desorption is greatest. The gas densities are sizeable and detectable (> 4000/cc at 50 km).
What What We Know Is There Looks Like-II Based on what we know is there: Assaying the lunar exosphere requires that we access a large volume of the space above the Lunar surface; In general, the closer you go to the surface, the better; The distribution of each species is different, and the distribution is variable.
What What We Know Is There Looks Like--Dust There is additional evidence for dust from the Apollo 17 ALSEP LEAM experiment, and from Clementine Observations. Surveyor 6 Horizon Glow at Twilight.--most likely explanation is forward scattering of Sunlight by dust Cernan sketched observations of streamers in the Sunrise horizon as the CSM approached local sunrise. Based on what data we have on dust: Most of the dust is close to the surface; Most of the dust is small.
LADEE Science Definition Team Began recruiting a small LADEE Science Definition Team early in February. Very focused direction--composition of atmosphere, and Characterization of dust. Constrained to 3 instruments and a target payload mass of 20 Kg--encouraged to think off the shelf in response to aggressive launch date. Work with ARC orbiter design for a low orbit (50 km), and a minimum 3 month prime mission. Mid-term report expected no later than April 21, with Final Report by May 21---both met. SDT could work with project--we did. RFI assessment completed after the SDT report was submitted by HQ/GSFC/ARC team.
Science Definition Team Laurie Leshin, NASA Goddard Space Flight Center (Chair) William Farrell, NASA Goddard Space Flight Center (Vice Chair) Dana Crider, Catholic University of America Rick Elphic, NASA Ames Research Center Paul Feldman, Johns Hopkins University Dick Hodges, University of Texas at Dallas (Emeritus) Mihaly Horanyi, University of Colorado Wayne Kasprazak, NASA Goddard Space Flight Center Richard Vondrak, NASA Goddard Space Flight Center Ex Officio Members Steve McClard, NASA Marshall Space Flight Center, LADEE Mission Manager Butler Hine, NASA Ames Research Center, LADEE Project Manager Will Marshall, NASA Ames Research Center, LADEE Flight Dynamics Thomas Morgan, NASA HQ, HQ Liaison Sarah Noble, NASA HQ, HQ Liaison Kelly Snook, NASA HQ, HQ Liaison With help from IMS focus group (R. Elphic, lead): M. Collier, E. Sittler, J. Keller NASA/GSFC
LADEE Atmosphere Findings - Species that make up exosphere 1)prevalent at 50 km altitude 2)maximize at sunrise terminator 3)peak densities at equator - Species can be categorized by their sources, including solar wind, regolith and radiogenic - Ar, He, H/H 2, OH, CH 4, CO, CO 2, Na, K, Si, Al, Fe all of interest - No one instrument/technique can obtain all species of interest - Mission lifetime of a year is ideal, but new, interesting science can be done in 3 mo. - A NMS will likely detect Ar, He, H 2 but will have great difficulty with trace species requiring a supporting instrument Model results from R. Hodges for LADEE SDT
LADEE Dust Findings - Two dust components: 1)Dust of Lunar Origin (DoLO) 2)Interplanetary Dust (IDP) - DoLO peaks near terminator with 50 km densities at ~10 -4 /cc, IDP detected at all longitudes - Distinct Targets-of-Opportunity for improved dust observations: Known meteor shower/comet tails Magnetotail/plasma sheet crossings Solar Storms - DoLO single impacts very difficult to detect since grains are submicron and slow - Remote sensing UV/VIS instrument will provide critical complementary data to in situ observations Clementine 94 Stubbs et al 2006
11 LADEE Dust Recommendations - Any in situ dust detector needs sensitivity to submicron levels to detect DoLO - Take full advantage of periods when external environment is being driven extra hard, like during solar storms, plasma sheets crossings, meteor showers - Because of difficulty in DoLO detection, recommend the use of supporting remote sensing UV/VIS sensor - At least one lunation to get through tail, likely see a meteor shower and solar storm M. Horanyi for SDT
12 LADEE Spacecraft/Trajectory Findings - Most active science location: Periseline at < 50 km over sunrise terminator - Retrograde orbit (keep instruments in ram but out of sunshine) - Equatorial orbit preferred over polar orbit: Densest portion of exosphere, dont expect emitted polar water from cold traps. LADEE can contribute to search for water by following the OH and examining the terminator desorption processes - Ideal orbit: Circular, retrograde, low inclination - Spacecraft is dirty and will have the potential to contaminate instruments via outgassing, thruster firings, and EMI
14 LADEE Mission Timeline 2/4/2008 - LADEE Announced 4/7/2008 - LADEE Authorization Letter from AA/SMD 3/24/2008 - LADEE Instrument RFI Released 4/1/2008 - LADEE Spacecraft Technical Interchange Meeting 4/8/2008 - PPBE Submit to SMD 4/21/2008 - Launch Accommodation Study Completed 5/21/2008 - Science Definition Team Final Report 8/12/2008 - Initial Payload Concept Studies Completed 8/19/2008 - SMD Guidance on LLCD Payload 8/20/2008 - Flight Planning Board Approval for Minotaur V 8/24/2008 - Initial Payload Accommodation Study Completed 10/1/2008 - Project Mission Concept Study Guidance Received 10/21/2008 - Mission Concept Study Kick-Off 12/8/2008 - Mission Concept Review Scheduled DATEACTION
15 Programmatics-I Lunar Atmosphere & Dust Environment Explorer (LADEE ) Mission Objectives Determine the composition of the lunar atmosphere and investigate the processes that control its distribution and variability, including sources, sinks, and surface interactions Characterize the lunar exospheric dust environment and measure any spatial and temporal variability and impacts on the lunar atmosphere Demonstrate LLCD Create a low cost reusable spacecraft architecture that can meet the needs of certain Planetary Science Missions Demonstrate the use of Minotaur V as a launch vehicle for planetary mission Key parameters Launch: 2011 Science Data Acquisition: 3 months (following short check out period) after which we demonstrate Laser communication Spacecraft Type: Small Orbiter - Category 3, Class D Provider: ARC provided small sat (partnered with GSFC) Cost: $100M LADEE with 3 science instruments; $46M LV $54M LLCD
16 Programmatics-II Instruments Science Instruments: NMS (directed to GSFC), UV/VIS (directed to ARC), and Dust Detector (competed through the SALMON AO (on the street) Technology Payload: Lunar Laser Communications Demonstration (LLCD) instrument ( LLCD), funded by SOMD (managed by GSFC). Science Team The Project Scientist will provide science team coordination functions Science decisions arrived at by consensus between the Instrument Pis through Project Science Group (PSW) Conflicts that cant be resolved internally will be elevated to the LADEE Program Scientist Each directed instrument will each contribute three members to the initial science team The Dust team element of the Science Team will be determined through the AO competition A Participating Scientist call will be offered through the ROSES Launch Vehicle Minotaur V (out of Wallops)--still requires DoD approval
LADEE Science Requirements In order to accomplish the science objectives, the LADEE mission shall meet the following baseline science requirements: o Measure spatial and temporal variations of Ar, He, Na, and K over time scales from several (3) lunar orbits to one lunation. o Detect or obtain new lower limits for other species for which observations have been made. These include the following elements or compounds and the current limit * (part/cm 3 ); CH 4 (1x10 4 ), S(150), O(1x10 3 ), Si(48), Kr(2x10 4 ), Xe(3x10 3 ), Fe(3.8x10 2 ), Al(55), Ti (1), Mg(6x10 3 ), OH(1x10 6 ), and H 2 O(100). o Search for other species (beyond those listed in the previous two bullets) or positive ambient ions of these species and other atoms or compounds in the 2-150 Da mass range. o Detect or set upper limits as small as 10 -4 dust particles / cm 3 from 1.5 to 50 km altitude for particles as small as 100 nm via occultation measurements. o Detect or set upper limits on the dust population at 50 km. *Limits measured against Table 1.1, S. A. Stern, Reviews of Geophysics, 37, 453, 1999. (Stern contains no limit for H 2 0)
18 Lunar Atmosphere and Dust Atmospheric Explorer Neutral Mass Spectrometer The Lunar Atmosphere and Dust Atmospheric Explorer (LADEE) Neutral Mass Spectrometer (NMS) will (with the Ultraviolet Spectrometer-next chart) determine the composition of the lunar atmosphere from an orbit of 50 km above the surface and for a period of one lunation. Features: NMS is a high sensitivity quadrupole mass spectrometer with a mass range to 150 Dalton and unit mass resolution. For lunar orbits of 50 km or lower NGIMS can measure the abundance and variability of helium, argon, methane and other species either released from the deep lunar interior or from the surface of the moon. The NM is designed to produce a substantial improvement in sensitivity and spatial coverage from Apollo era instruments. It will characterize this environment before it is irreversibly changed by human activity. Team: Instrument PI: Dr. Paul Mahaffy/GSFC Instrument Manager: Jim Kellogg/GSFC
19 Lunar Atmosphere and Dust Atmospheric Explorer Neutral Mass Spectrometer The Lunar Atmosphere and Dust Atmospheric Explorer (LADEE) Neutral Mass Spectrometer (NMS) will (with the Ultraviolet Spectrometer-next chart) determine the composition of the lunar atmosphere from an orbit of 50 km above the surface and for a period of one lunation. Features: NMS is a high sensitivity quadrupole mass spectrometer with a mass range to 150 Dalton and unit mass resolution. For lunar orbits of 50 km or lower NGIMS can measure the abundance and variability of helium, argon, methane and other species either released from the deep lunar interior or from the surface of the moon. The NM is designed to produce a substantial improvement in sensitivity and spatial coverage from Apollo era instruments. It will characterize this environment before it is irreversibly changed by human activity. Team: Instrument PI: Dr. Paul Mahaffy/GSFC Instrument Manager: Jim Kellogg/GSFC
20 LADEE Atmosphere UV/Vis Measurements Measured Atmospheric Species (At SNR=5) Dust Occultation Detection Limit -Target A: For known species (Na, K; use them as markers for variability -Target B: For expected species, reduce known limit or make the discovery detection -Sample species in each of three source categories -Monitor dust component - Measure for at least one lunation
29 Artemis Mission Concept Probe instruments: ESA: ElectroStatic Analyzer (coIs: Carlson and McFadden) SST: Solid State Telescopes (coI: Larson) FGM: FluxGate Magnetometer (coIs: Glassmeier, Auster & Baumjohann) SCM: SearchCoil Magnetometer (coI: Roux) EFI: Electric Field Instrument (coI: Bonnell) SST ESA EFIa EFIs FGM SCM T spin =3s D2925-10 @ CCAS Combined Goals Heliophysics from the Moon EM Environment of the Moon Dust Levitation in E-field Composition of the Exosphere Distribution of the Exosphere EM sounding of Interior