THE FUTURE OF THE ARECIBO OBSERVATORY:
THE NEXT GENERATION ARECIBO TELESCOPE
Contact Author: D. Anish Roshi1, email@example.com
Authors: N. Aponte1, E. Araya2 , H. Arce 3 , L. A. Baker7 , W. Baan35 , T. M. Becker4 , J. K. Breakall34 , R. G. Brown5 , C. G. M. Brum1 , M. Busch6 , D. B. Campbell7 , T. Cohen24 , F. Cordova1 , J. S. Deneva8 , M. Devogèle1 , T. Dolch30 , F. O. Fernandez-Rodriguez1 , T. Ghosh9 , P. F. Goldsmith10 , L. Gurvits27 , M. Haynes7 , C. Heiles11 , D. Hickson1 , B. Isham12 , R. B. Kerr 13 , J. Kelly28 , J. J. Kiriazes5 , S. Kumar14 , J. Lautenbach1 , M. Lebron15 , N. Lewandowska16 , L. Magnani17 , P. K. Manoharan1 , S. E. Marshall1 , A. K. McGilvray1 , A. Mendez36 , R. Minchin18 , V. Negron1 , M. C. Nolan19 , L. Olmi26 , F. Paganelli9 , N. T. Palliyaguru20 , C. A. Pantoja15 , Z. Paragi27 , S. C. Parshley7 , J. E. G. Peek6,21 , B. B. P. Perera1 , P. Perillat 1 , N. Pinilla-Alonso22,1 , L. Quintero1 , H. Radovan37 , S. Raizada1 , T. Robishaw23 , M. Route31 , C. J. Salter9,1 , A. Santoni1 , P. Santos1 , S. Sau1 , D. Selvaraj1 , A. J. Smith1 , M. Sulzer1 , S. Vaddi1 , F. Vargas33 , F. C. F. Venditti1 , A. Venkataraman1 , A. K. Virkki1 , A. Vishwas7 , S. Weinreb32 , D. Werthimer11 , A. Wolszczan29 and L. F. Zambrano-Marin1.
Affiliations are listed after the acknowledgements, immediately before the appendices in the Full Version.
The Arecibo Observatory (AO) hosted the most powerful radar system and the most sensitive radio telescope in the world until the unexpected collapse of the 1000-ft “legacy” AO telescope (LAT) on December 1, 2020. For 57 years, the facility uniquely excelled in three separate, major scientific areas: planetary science, space and atmospheric sciences, and astronomy. Through its final day of operation, the LAT continued to produce new, groundbreaking science, adding to its long history of extraordinary achievements, including a Nobel Prize in Physics. Its collapse has produced a significant void in these scientific fields, which echoed across the extensive, world-wide scientific community. It also produced a deeply-felt cultural, socioeconomic, and educational loss for Puerto Ricans, and a tragic deprivation of opportunity, inspiration, and training for Science, Technology, Engineering, and Mathematics (STEM) students in Puerto Rico and across the U.S., all of whom represent the next generation of America’s scientists and engineers. In the tremendous wake of the LAT, we envision a new, unparalleled facility, one which will push forward the boundaries of the planetary, atmospheric, and radio astronomical sciences for decades to come. A future multidisciplinary facility at the site should enable cutting-edge capabilities for all three of the science branches that form the cornerstones of AO exploration. To facilitate the novel, consequential science goals described in this document, the new facility must meet the capability requirements described below, which ultimately drive our telescope concept design.
Planetary Radar Science
A key role of the LAT as the host to the world’s most powerful radar system was to characterize the physical and dynamical properties of near-Earth objects (NEOs), in support of NASA’s Planetary Defense Coordination Office and in line with national interest and security. In recent years, AO observed hundreds of NEOs as a part of NASA’s mandate by the US Congress [George E. Brown, Jr. [ADD: Near-Earth Object Survey] Act (Public Law 109-155 Sec. 321)] to detect, track, catalogue, and characterize 90% of all NEOs larger than 140 meters in size. Post-discovery tracking of NEOs with radar is an unparalleled technique for accurately determining their future trajectory and assessing whether they pose a real impact threat to Earth. These radar measurements secure the position and velocity of NEOs with a precision of tens of meters and millimeters per second, respectively. The LAT radar was also used to map the surfaces of Mercury, Venus, Mars, and the Moon, supporting human and robotic exploration of the Moon, Mars, and near-Earth asteroids. A new facility, with a more powerful radar system (5 MW at 2 to 6 GHz) and large sky coverage, will support Planetary Defense, Solar System science, and Space Situational Awareness by providing the following capabilities:
Planetary Defense and Solar System Exploration
Post-discovery characterization and orbit determination of up to 90% of possible asteroid impactors
Study the surface and sub-surface of ocean worlds around Jupiter, Saturn and other Solar System objects
Observe asteroids in the outer regions of the main-belt and beyond
Space Situational Awareness (SSA) to categorize space debris down to mm-size in LEO, and smaller than one meter in GEO and cislunar space
Support NASA Human Exploration program by characterizing spacecraft landing sites and identifying potential hazards at low cost
Support and extend the science return of missions including NASA’s DART, Janus, Europa Clipper, and Dragonfly missions; and ESA’s JUICE mission
Space and Atmospheric Sciences
Space and Atmospherics Sciences (SAS) at AO has traditionally utilized multiple approaches to atmospheric research. The LAT’s Incoherent Scatter Radar (ISR), the Light Detection and Ranging (Lidar) facility, the onsite and remote passive optical facilities, and the High Frequency facility formed the cornerstones of SAS research at AO. The powerful LAT’s ISR was the only instrument of its kind and was capable of profiling ionospheric parameters beyond 2000 km of the Earth’s atmosphere. The high resolution, range-resolved observations of electron concentrations, temperatures, ion compositions, and inference of electric fields in the ionosphere are important for the investigations of the coupling processes between different atmospheric regions, influence of solar and space weather disturbances on the Earth’s environment, and fundamental plasma processes, since the ionosphere acts as a natural plasma laboratory. The LAT’s ISR provided unique contributions in the space sciences due to its high sensitivity and power. However, a major drawback was its limited beam steering capabilities, which will be overcome with the proposed new facility. Increased sky coverage (>±45° zenith coverage), and more power (≳ 10 MW at 430 MHz; a 220 MHz radar is also under consideration) open up new possibilities that will lead to innovative research and discoveries in the following topics
Advances in Space and Atmospheric Sciences
Investigate global climate change and its influence on the upper atmosphere
Unravel the mysterious causes of short-period perturbations in the ionosphere
Understand interactions in Earth’s atmosphere in the northern and southern hemispheres
Investigate coupling between Earth’s atmospheric layers to improve satellite navigation, radio wave propagation, and weather forecasting models
Disambiguate between the influence of meteorological and space weather on the neutral and ionized coupling phenomena in Earth’s atmosphere
Understand the neutral and ionized atmospheric behavior by combined active and passive observations
LAT’s unique capabilities enabled several key discoveries in radio astronomy. The loss of the instrument was felt most keenly by pulsar, galactic and extragalactic researchers. The new facility should enable complementary observations with other existing and upcoming radio facilities. For example, the new facility must provide a substantial increase in sensitivity for Very Large Baseline Interferometry, of which the LAT was a contributing instrument whenever higher sensitivity was required. In addition, wider sky coverage, greater collecting area, increased frequency coverage, and a larger field-of-view (FoV) will substantially increase the research potential in a wide range of fields, some of which are highlighted below.
New Frontiers in Radio Astronomy
Test General Relativity with Galactic Center pulsars
Illuminate underlying physics of pulsars, the emission mechanism, and propagation of radio waves in the interstellar medium
Gain new insights into the causes and physical processes of Fast Radio Bursts
Constrain cosmological theories for Dark Matter in the local Universe
Search for Exoplanets and Earth-like Worlds including studies on habitability and magnetic fields
Measure the distribution of matter to moderate redshifts to constrain Dark Energy
Observe Active Galactic Nuclei with Very Long Baseline Interferometry
Detect the fingerprints of prebiotic molecules in our Galaxy and beyond
Detect and study Gravitational Waves using pulsar timing
Probe the star formation history of the Universe by observing 12CO emission from massive galaxies at redshift > 3
Study the formation of massive stars through ammonia observations
Search for Technosignatures from advanced life forms
Interdisciplinary science - Space Weather Studies
The US “space weather preparedness” bill [116th Congress Public Law 181 (10/21/2020)] emphasizes the importance of space weather research and forecasting efforts. It is important to efficiently track and understand the propagation and dynamics of solar storms to improve space weather forecasting and to provide sufficient warnings for the safety of the technological systems and humans in space. The new capabilities for interplanetary space observations enabled by extended FoV coverage will facilitate solar wind measurements that probe the dynamics of space weather between the Sun and Earth at several points inaccessible to current space missions, with the goal of improving the lead time and advanced warning capabilities for space weather events.
Forecasting Space Weather
Protect humans in space and ground and space-based technology by tracking solar storms and predicting their arrival at Earth
Study the effects of space weather on Earth’s atmosphere and the near-Sun environment
Perform high frequency and spatial resolution observations of solar radio bursts associated with powerful coronal mass ejections
The Concept of a Next Generation Arecibo Telescope
In order to accomplish the overarching scientific goals stated above, we present a concept for the Next Generation Arecibo Telescope (NGAT) - an innovative combination of a compact, phased array of dishes on a steerable plate-like structure. Compared to the LAT, the NGAT will provide 500 times wider field of view, 2.5 times larger sky coverage, 3 times more frequency coverage, nearly double the sensitivity in receiving radio astronomy signals, and more than four times greater transmitting power required for both Planerary and Atmospheric investigations. We summarize the new capabilities and direct applications of this facility in Table 1. The new telescope will coexist with an extended High Frequency (HF) facility, and a diverse set of radio and optical instrumentation that continue to operate at AO and at the Remote Optical Facility (ROF). The largely new proposed concept for a radio science instrument requires extensive engineering studies that will be the next step to ensure the new facility achieves the driving scientific requirements for the aforementioned science objectives.
Table 1: The significant technical improvements of the proposed concept and their impacts on the science studies.
The Necessity to Rebuild in Arecibo, Puerto Rico
We propose that NGAT be located at the Arecibo Observatory, preferably at the location of the LAT to take advantage of the existing infrastructure and the extension of the RFI active cancellation system, an active project in development at the AO location. Several other advantages for the Arecibo site include:
Contents of the white paper
This white paper was developed in the two months following the collapse of LAT through discussions with hundreds of scientists and engineers around the world who support the construction of a new and more powerful telescope at AO site. Our goal is to acquire vastly enhanced capabilities that will open exciting new possibilities for the future of radio science with direct applications for planetary defense and the protection of US satellites and astronauts. The remainder of this white paper is outlined as follows: the Introduction (Section 1) includes the context for the push to construct NGAT at the AO site. We discuss the Key Science Goals for planetary science, atmospheric science, and astronomy in Section 2 after first defining the new facility’s projected capabilities. In Section 3 we discuss the NGAT concept. Following the main text, we discuss alternative concepts considered for the new facility in Appendix A. An important extension of the NGAT’s capabilities in space and atmospheric sciences relies on relocating the High Frequency facility within the AO site, and we describe these plans in Appendix B. Appendix C describes additional science objectives the NGAT concept will enable to continue or improve, and finally, we discuss other AO science activities that interlock with NGAT in Appendices D and E. A summary of the contents of Appendix C and D is listed below. The acronyms used in the document are defined in Appendix F. Page numbers are provided in a Table of Contents starting on page 11.