REMOTE MEASUREMENT OF LUNAR HEAT FLOW FROM EARTH BASED RADIO ASTRONOMYSCIENTIFIC OBJECTIVES: THE PRIMARY OBJECTIVE OF THIS STUDY IS TO BETTER CONSTRAIN THE GEOTHERMAL HEAT FLUX FROM THE LUNAR INTERIOR USING VLA PASSIVE RADIO OBSERVATIONS OF THE LUNAR NEARSIDE. CURRENTLY WE HAVE ONLY TWO VALUES OF LUNAR HEAT FLOW FROM THE APOLLO 15 AND 17 MISSIONS WITH A POTENTIAL 3RD UPPER LIMIT MEASUREMENT FROM DIVINER LUNAR RADIOMETER (DIVINER) MEASUREMENTS NEAR THE LUNAR SOUTH POLE [SIEGLER ET AL. 2014 PAIGE ET AL. 2016]. USING C L AND P BAND (~6 21 AND 90CM WAVELENGTH) PASSIVE RADIO MEASUREMENTS OF THE LUNAR NEARSIDE WE CAN POTENTIALLY CONNECT THESE DATA TO CONSTRAIN THE LUNAR NEAR SIDE AT ~100KM RESOLUTION. AS IN THE APOLLO HEAT FLOW EXPERIMENTS (HFE) [E.G. LANGSETH ET AL. 1976] AND THE UPCOMING INSIGHT MISSION MEASUREMENTS OF THE TEMPERATURE GRADIENT AT DEPTH CAN BE USED TO CHARACTERIZE THE GEOTHERMAL HEAT PRODUCTION OF A PLANET. PASSIVE RADIO-WAVELENGTH MEASUREMENTS HAVE BEEN LONG SUGGESTED [E.G. KEIHM ET AL. 1975] AS A METHOD FOR CONSTRAINING THERMAL EMISSION (AND THEREFORE THE TEMPERATURE GRADIENT) FROM SEVERAL METERS BELOW THE SURFACE. HOWEVER A MAJOR SOURCE OF ERROR ON SUCH A MEASUREMENT IS THE EMISSION FROM THE NEAR SURFACE WHICH VARIES DIURNALLY WITHIN THE UPPER METER. SUCH LIMITATIONS HAVE LED TO LITTLE MORE BEING DONE ON THE TOPIC THAN FULL-DISC OBSERVATIONS IN THE 1960 S AND 70 S. WITH THE VLA AND ARECIBO WE CAN INCREASE THE RESOLUTION BY A FACTOR OF 30 POTENTIALLY MAPPING NEARSIDE HEAT FLOW TO 100KM RESOLUTION. NEW DATA FROM THE DIVINER AND CHANG E 1 AND 2 PASSIVE MICROWAVE RADIOMETERS NOW ALLOWS DETAILED CONSTRAINT ON THIS NEAR SURFACE EMISSION. THESE INSTRUMENTS HAVE REVOLUTIONIZED OUT UNDERSTANDING OF INFRARED AND MICROWAVE BRIGHTNESS TEMPERATURES OF THE UPPER ~1M OF THE LUNAR SURFACE (ASSUMING ~10 WAVELENGTHS PENETRATION). COMBINED WITH THERMAL MODELS DESIGNED TO REPRODUCE DIVINER TEMPERATURES WE SHOULD NOW BE ABLE TO CHARACTERIZE THIS NEAR SURFACE EMISSION PRECISELY ENOUGH TO CONSTRAIN EMISSION FROM DEPTH ALONE. METHODOLOGY: L-BAND(~21CM) AND P-BAND(~90CM) MEASUREMENTS WILL BE USED TO BACK OUT PHYSICAL TEMPERATURE AS A FUNCTION OF DEPTH ON THE MOON IN THE UPPER ~10M. L-BAND WILL COLLECT THERMAL EMISSION WITHIN THE UPPER ~2M P-BAND WITHIN THE UPPER ~9M. FOR A SYNTHESIS IMAGING INSTRUMENT LIKE THE VLA A SPATIAL DYNAMIC RANGE OF ~30-40 BEAMS IS TYPICAL MEANING THAT WE NEED A SPATIAL RESOLUTION OF ~45 . THIS CAN BE ACHIEVED AT P-BAND IN THE C-CONFIGURATION AND AT L-BAND IN THE D-CONFIGURATION. THIS WILL YIELD A PHYSICAL RESOLUTION OF ~100 KM ON THE SURFACE OF THE MOON. VLA IS NOT ABLE TO MAKE FULL LUNAR MAPS AT SHORTER WAVELENGTHS LEADING TO A DESIRE TO MAP C-BAND (~6CM) DATA WITH ARECIBO WHICH COINCIDENTALLY WILL ALSO BE ~30-35 BEAM SPOTS ACROSS THE MOON RESULTING IN A COMPARABLE MAP TO THE VLA LONG WAVELENGTH DATA. THIS WILL REQUIRE TWO SEPARATE OBSERVING CAMPAIGNS AT THE VLA AS THESE CONFIGURATIONS ARE CHANGED EVERY 4 MONTHS AND ONE CAMPAIGN AT ARECIBO. EACH CAMPAIGN WILL IDEALLY INVOLVE MEASUREMENTS AT 3 PHASES WITHIN THE LUNAR MONTH TO AID IN CHARACTERIZATION OF THE DIURNAL COMPONENT OF THERMAL EMISSION. MODELS OF SUBSURFACE TEMPERATURES AND HEAT FLUX WILL BE USED TO PRODUCE FORWARD MODELS OF THERMAL FLUX CONSISTENT WITH THE TELESCOPE(AND EXISTING DIVINER AND CHANG E) OBSERVATIONS. RELEVANCE TO THE NASA SOLAR SYSTEM OBSERVATIONS PROGRAM: SSO SOLICITS OBSERVATIONS AT ALL WAVELENGTHS INCLUDING RADIO THAT CONTRIBUTE TO THE UNDERSTANDING OF THE NATURE AND EVOLUTION OF THE SOLAR SYSTEM BODIES. CONSTRAINING THE INTERNAL HEAT PRODUCTION OF THE MOON WAS A DESIRED GOAL OF THE NASA PLANETARY DECADAL SURVEY AND SUCH A MEASUREMENT MAY BE A VALUABLE PRECURSOR TO THE PROPOSED LUNAR GEOPHYSICAL NETWORK LISTED IN THAT DOCUMENT.