Goldstone Apple Valley Radio Telescope Research Articles

The Goldstone Apple Valley Radio Telescope (GAVRT) Search for Extra Terrestrial Intelligence (SETI)

This paper reports the results from a student-led Search for Extraterrestrial Intelligence (SETI), also known as technosignatures, targeting the plane of the Milky Way as a part of the Goldstone Apple Valley Radio Telescope (GAVRT) collaboration between the Lewis Center for Educational Research (LCER) and the Jet Propulsion Laboratory. Students associated with LCER submit analytic reports of spectral data targeting specific regions of the Milky Way, identifying interference, noise, and Candidate signals potentially originating from intelligent sources. GAVRT-SETI's search is guided by the assumption that a narrow-band radio signal (<1.5 Hz) from a fixed location in the sky, occurring across multiple observation periods, is unlikely to be caused by instrument noise or by a natural source. Thus, we searched the reported data for similar signals occurring during different observation periods within the same region of sky. No such signals were found. However, our analysis of the frequency distribution of Candidates suggests that at least a few percent of the Candidates are associated with low-level radio-frequency interference.

Variability of Jupiter’s Synchrotron Radiation: Goldstone Apple Valley Radio Telescope (GAVRT) Observations -II

Jupiter’s decimeter-wavelength flux density is dominated by synchrotron emission from magnetically trapped ∼5–50 MeV electrons in the radiation belts. Synchrotron radio emission remains the most useful diagnostic of the radiation belts, and a global picture is provided by ground-based observations. Monitoring of the long-term variations of Jupiter’s Synchrotron Radiation (JSR) flux density is crucial to understanding its relationship with the solar wind. The GAVRT (Goldstone-Apple Valley Radio Telescope) program operates two retired Deep Space Network (DSN) antennas, and as part of their K-12 program and Juno support, GAVRT has been collecting data to monitor JSR radio emission at 2280 MHz (13 cm wavelength). We present new results from 2019 August to 2021 December GAVRT monitoring observations. As viewed from Earth the JSR varies systematically (by about 10%) with Jupiter’s 9.9 hr rotation period, and our observations were typically much shorter than 9.9 hr. To estimate the daily flux density of JSR, we took advantage of recent progress in modeling the radiation belt, scaling individual observations by the predicted relative variation due to Jupiter’s rotation as viewed from Earth. We discuss the JSR variability from 2015 to 2021, combining our results with previous GAVRT data. Our new results show a marked decrease (∼1 Jy) in JSR flux density between 2018 and 2021, while earlier observations showed an increase from 2015 to 2018. These results are remarkably consistent with long-term variability shown by the simulations of Han et al. based on models driven by the solar wind ram pressure.

Goldstone Apple Valley Radio Telescope Monitoring Flux Density of Jupiter's Synchrotron Radiation during the Juno Mission

Goldstone Apple Valley Radio Telescope (GAVRT) is a science education partnership among NASA, the Jet Propulsion Laboratory (JPL), and the Lewis Center for Educational Research (LCER), offering unique opportunities for K-12 students and their teachers. As part of a long-term Jupiter synchrotron radiation (JSR) flux density monitoring program, LCER has been carrying out Jupiter observations with some student participation. In this paper we present the results of processed data sets observed between 2015 March 6 and 2018 April 6. The data are divided into 5 epochs, grouped by time and by Jupiter’s ephemeris parameters as observed from Earth. We derive JSR beaming curves at different epochs and Earth declinations. We present a comparison of the observed beaming curves with those derived from most recent models for the radiation belts. Our results show an increasing trend of the JSR flux density which seem consistent with the models for the magnetospheric solar wind interactions.

Goldstone Apple Valley Radio Telescope Observations of 2012 Solar Eclipse: A Multi-wavelength Study of cm-λ Gyroresonance Emission from Active Regions

Goldstone Apple Valley Radio Telescope (GAVRT) is a science education partnership among NASA, the Jet Propulsion Laboratory, and the Lewis Center for Educational Research, offering unique opportunities for K-12 students and their teachers. The GAVRT program operates a 34 m radio telescope with a wide-band, low noise receiver, which is tunable in four independent dual-polarization bands from 3 to 14 GHz. The annular eclipse of the Sun on 2012 May 20 was observed by GAVRT as part of education outreach. In this paper we present the results of this eclipse data and discuss the multi-wavelength strip scan brightness distribution across three active regions. We derive the source brightness temperatures and angular sizes as a function of frequency and interpret the results in terms of the gyroresonance mechanism. We show examples of the increasing brightness and widening of source size (isogauss surface) with wavelength as evidence for gyroresonance emission layers of broader (diverging) isogauss surfaces of the magnetic field geometry in the corona above solar surface. We present an example how the derived frequency–brightness temperature relationship is translated to a magnetic field–brightness temperature relationship under the frame-work of gyroresonance emission. Our results demonstrate the usefulness of GAVRT bands as excellent probes to study the layers of the corona above the active regions (Sun spots), in particular the prevalence of the gyroresonance mechanism. Our results provide a frame-work for multiwavelength cm-λ eclipse observations and illustrate how the GAVRT program and K-12 student/teacher participation can produce science data useful to the scientific community and science missions.

An Automated Approach to Modeling Jupiter’s Synchrotron Radiation from Radio Telescope Observations

In this study, we used 2.295 GHz radio telescope data to study synchrotron radiation from Jupiter’s magnetosphere. We processed scans of Jupiter and calibrators taken by the Goldstone Apple Valley Radio Telescope on various dates, developing and automating algorithms for outlier removal, baseline subtraction, and Gaussian fitting in order to determine the peak intensity of each scan. Comparing the peak intensities of Jupiter to those of the calibrators and the known fluxes of the calibrators, we computed the flux of Jupiter on each scan. Plotting Jupiter’s flux against the longitude facing Earth at the time of each scan revealed a periodic relationship between the variables and thus a model for expected synchrotron flux from Jupiter observed at a given longitude. This estimate can corroborate other flux measurements of Jupiter at similar frequencies, such as those taken by the microwave radiometer on the Junoprobe.

Inspiring the next generation of scientists with their observations of quasars, black holes, Jupiter, and SETI with the Goldstone Apple Valley Radio Telescope, GAVRT

This paper describes a radio astronomy programfor schools, the Goldstone-AppleValley Radio Telescope,GAVRT. The GAVRT program is designed to bring the inspiration and enthusiasm to a younger generation of teachers and children who learn about science by doing real science, just as Iosif Shklovsky brought to an older generation.

The Design and Performance of a Wideband Radio Telescope for the GAVRT Program

A wideband Radio Telescope was designed and built for use in the Goldstone Apple Valley Radio Telescope (GAVRT) program. It uses an existing 34-m antenna retrofitted with a tertiary offset mirror placed at the vertex of the main reflector. It can be rotated to allow using two feeds that cover the 0.5-14-GHz band. The feed for 4.0-14.0 GHz is a cryogenically cooled, commercially available, open-boundary quadridge horn from ETS-Lindgren. Coverage from 0.5 to 4.0 GHz is provided by an uncooled lower frequency version of the same feed that uses a cooled LNA. The measured aperture efficiency is greater than 40% over much of the band.

Long-term variations in the microwave brightness temperature of the Uranus atmosphere

We present a self-consistent, 36-year record of the disk-averaged radio brightness of Uranus at wavelengths near 3.5 cm. It covers nearly half a uranian year, and includes both equatorial and polar viewing geometries (corresponding to equinox and solstice, respectively). We find large (greater than 30 K) changes over this time span. In agreement with analyses made of more limited microwave data sets, our observations suggest the changes are not caused by geometric effects alone, and that temporal variations may exist in the deep uranian troposphere down to pressures of tens of bars. Our data also support an earlier suggestion that a rapid, planetary-scale change may have occurred in late 1993 and early 1994. The seasonal record presented here will be useful for constraining dynamical models of the deep atmosphere, and for interpreting observations made during Uranus' 2007 equinox passage. As part of a multi-wavelength observing campaign for this event, the Goldstone-Apple Valley Radio Telescope (GAVRT) project will continue to make frequent, single-dish observations near 3.5 cm.

Jupiter Quest

The authors describe a scientific endeavor that excites students and changes their thought processes as they embark on a journey of discovery. ALL SCIENCE teachers want to convey to students the true meaning of the scientific endeavor. We want them not just to understand science, but also to feel some part of the exhilaration that comes with scientific discovery. But there remains a significant difference between even advanced science classrooms and professional science. For students to get a taste of the world of professional science, they must have access to the scientific community and be given the chance to be real scientists. The Goldstone Apple Valley Radio Telescope (GAVRT) Project began as a proposal from two educators at the Lewis Center for Educational Research (then called the Apple Valley Science & Technology Center) in Apple Valley, California, to allow students in middle and high schools to experience science using a 34-meter radio antenna located at the Goldstone (California) facility of NASA's Deep Space Network. The dish had already been scheduled to be decommissioned. This idea has given rise to a partnership involving NASA (National Aeronautics and Space Administration), the Jet Propulsion Laboratory, and the Lewis Center for Educational Research. Today, the project has one complete curriculum package, called Jupiter Quest, and a number of others are under development. The new curriculum packages will focus on the sun/Earth relationship, the birth of new stars in our galaxy, and the mapping of radio sources on the galactic plane. The goal of all these curriculum packages is to allow students to step briefly into the world of professional research scientists and to experience the process of discovery. The Jupiter Quest curriculum concerns a hypothetical space mission to the Jovian system. Students work in teams to study Jupiter and its four largest moons. They perform experiments to understand science concepts that may be new to them, they observe Jupiter with the radio antenna, and they scrutinize data collected during observations. Then the students select Jupiter itself or one of its larger moons for further study and as a destination for a hypothetical manned or unmanned mission. They must consider environment, planetary geology, gravity, time, nutrition, and health concerns. In the process, they learn the importance of asking such questions as What further information is needed? and How do scientific teams plan missions to collect specific types of information? Depending on the focus of each class, students may investigate one or a few areas in depth while just touching on others. Skills in scientific reasoning, in the presentation of evidence, and in effective communication are stressed, while students learn the value of peer review and how research scientists discover, verify, and share information and ideas. Jupiter Quest, which partners middle schools and high schools nationwide with the Jet Propulsion Laboratory and the Lewis Center for Educational Research, engages students in the process of scientific discovery while helping teachers provide a standards-based course of study. At the close of the 1999-2000 school year, 58 teachers in 36 schools in nine states had been trained to use Jupiter Quest. This project gives students a chance to become part of a team whose members truly depend on one another. It gives them a chance to collect and process real-world scientific data, using state-of-the-art equipment and software, and to contribute that information to the scientific community. Because Jupiter Quest is a real investigation, not a simulation in which nothing ever goes wrong, students must learn to anticipate likely problems and to handle those that cannot be anticipated as they arise. After the data from the antenna have been collected and analyzed, they are posted on a special Internet site along with other Jupiter data collected by other radio antennas or arrays of antennas, and a long- term picture of Jupiter's radio emissions emerges. …