2103.01367.pdf

THE FUTURE OF THE ARECIBO OBSERVATORY: THE NEXT GENERATION ARECIBO TELESCOPE

THE FUTURE OF THE ARECIBO OBSERVATORY:

THE NEXT GENERATION ARECIBO TELESCOPE

White Paper, ver 2.0, 02-01-2021

______________________________________________________________

Contact Author: D. Anish Roshi

aroshi@naic.edu

Authors:

D. Anish Roshi

N. Aponte

, E. Araya

H. Arce

, L. A. Baker

, W.

Baan

T. M. Becker

, J. K. Breakall

, R. G. Brown

, C. G. M. Brum

, M. Busch

D. B. Campbell

, T. Cohen

, F. Cordova

, J. S. Deneva

, M. Devogèle

, T. Dolch

F. O. Fernandez-Rodriguez

, T. Ghosh

, P. F. Goldsmith

, L.I. Gurvits

14,27

, M.

Haynes

, C. Heiles

J. W. T. Hessel

35, 38

, D. Hickson

, B. Isham

, R. B. Kerr

J. Kelly

, J. J. Kiriazes

, J. Lautenbach

, M. Lebron

, N. Lewandowska

Magnani

P. K. Manoharan

, J. L. Margot

S. E. Marshall

, A. K. McGilvray

A. Mendez

, R. Minchin

, V. Negron

M. C. Nolan

, L. Olmi

, F. Paganelli

N. T. Palliyaguru

, C. A. Pantoja

, Z. Paragi

, S. C. Parshley

, J. E. G. Peek

6,21

B. B. P. Perera

, P. Perillat

, N. Pinilla-Alonso

22,1

, L. Quintero

, H. Radovan

S. Raizada

, T. Robishaw

, M. Route

C. J. Salter

9,1

, A. Santoni

P. Santos

S. Sau

, D. Selvaraj

A. J. Smith

, M. Sulzer

, S. Vaddi

, F. Vargas

, F. C. F.

Venditti

, A. Venkataraman

H. Verkouter

, A. K. Virkki

A. Vishwas

, S.

Weinreb

, D. Werthimer

, A. Wolszczan

and L. F. Zambrano-Marin

Affiliations are listed after the acknowledgements, immediately before the appendices.

Please click

here

to endorse the contents of this white paper.

THE FUTURE OF THE ARECIBO OBSERVATORY: THE NEXT GENERATION ARECIBO TELESCOPE

Table of Contents

Executive Summary

Planetary Radar Science

Space and Atmospheric Sciences

Radio Astronomy

Interdisciplinary science - Space Weather Studies

The Concept of a Next Generation Arecibo Telescope

The Necessity to Rebuild in Arecibo, Puerto Rico

Contents of the white paper

1.0 Introduction

2.0 Key Science Goals

2.1 Planetary Defense

2.2 Exploration of Planetary Surfaces and Ocean Worlds

2.3 Space Debris Monitoring

2.4 Incoherent Scatter Radar

2.5 Climate Change Investigation

2.6 Space Weather Forecasting

2.7 AO as a laboratory to test theories of Global Climate Change

2.8 Searching for Habitable Worlds

2.9 Detecting Gravitational Waves with Pulsar Timing Arrays

2.10 Probing innermost regions of AGN

2.11 Prebiotic Molecules: the Precursors to Life in the Universe

2.12 Pulsars near Sgr A*: a new test bed for General Relativity

2.13 Fast Radio Bursts, other energetic events

2.14 Quantifying the local Dark Matter content with HI 21cm Line

2.15 Probing Dark Energy with HI Intensity Mapping

2.16 Searching for Advanced Life in the Universe

2.17 Molecular Gas in the distant Universe

2.18 High Mass Star Formation in the Galaxy

3.0 NGAT Design Concept

3.1 Compact dish array on a single plane

3.2 New Capabilities

3.3 Summary of example configurations

3.4 Rough Order of Magnitude Cost estimate

4.0 Summary

Acknowledgements

THE FUTURE OF THE ARECIBO OBSERVATORY: THE NEXT GENERATION ARECIBO TELESCOPE

Affiliations (for author list)

Appendix A: Alternate Design Concepts Considered

A.1 A Single Dish

A.2 An Array of Individually Pointing Dishes

Appendix B: A High Frequency Facility with Extended Capabilities

Appendix C: Additional Science Studies that are enhanced by NGAT

C.1 Planetary Science

C.2 Solar, Heliospheric, and Space Weather studies

C.2.1 Solar Wind and Space Weather studies

C.2.2 Highly Efficient Heliospheric Sampling, Space Weather events

C.2.3 Tracking Coronal Mass Ejections

C.2.4 Internal Magnetic Field of CMEs and Faraday Rotation

C.2.5 Solar Radio studies

C.2.6 Solar Wind and Space Weather Impacts on AIMI System

C.2.7 In-situ Data Comparison and Cometary Plasma Tail investigations

C.3 Pulsar studies

C.3.1 Pulsar searches

C.3.2. Binary pulsars

C.3.3. Pulsar Emission Mechanism and individual pulses

C.4. VLBI studies

C.5 New high-frequency explorations in Radio Astronomy

C.5.1 Probing the nature of early and late-type stellar evolution

C.5.2 Pulsars and radio transients at high frequencies

C.5.3 Zeeman measurements to detect Galactic Magnetism

C.6 A comprehensive snapshot of the Galactic Plane

C.7 Near-Field HI 21 cm Line Cosmology

C.8 Detection of Galactic Cold Dark Matter, standard model of particle physics

C.9. Space and Atmospheric Sciences

C.9.1 Ion-Neutral Interactions

C.9.2 Sudden Stratospheric Warming Events (SSW)

C.9.3 Plasmaspheric studies and modeling

C.9.4 Inter-hemispheric flux of particles and its impacts on the Caribbean Sector

C.9.5 Atmosphere-ionosphere-magnetosphere interactions (AIMI)

C.9.6 Vertical coupling of the Earth’s atmospheric layers

C.9.6.1 Science Driver for the NGAT 220 MHz Coherent Radar

C.9.6.2 Wave energy in the F-region thermosphere

C.9.6.3 Climatology, morphology and equatorward propagation (MSTIDs)

C.9.6.4 Tropospheric Forcing on the upper atmosphere

C.9.6.5 Aerosol and Coupling Processes in the Lower Atmosphere

THE FUTURE OF THE ARECIBO OBSERVATORY: THE NEXT GENERATION ARECIBO TELESCOPE

Appendix D: Other science activities at the Arecibo Observatory that interlock

with the NGAT

D.1 Space and Atmospheric Sciences

D.1.1 Ion Transport Processes using Lidars and ISR

D.1.2 Climate Studies and Forcing of the Ionosphere from below using Lidars

D.1.3 Geocoronal hydrogen: Secular change and storm response

D.1.4 Horizontal winds as a function of altitude

D.1.5 The AO Remote Optical Facility (ROF) in Culebra Island

D.1.5.1 High Doppler resolution measurements of vertical motion

D.1.5.2 Field line diffusion of HF produced electrons as a function of energy

D.1.5.3 First Caribbean meteor radar application

D.2 12m Telescope

D.3 e-CALLISTO spectrometer

Appendix E: Study of planetary subsurfaces with 40-60 MHz radar

Appendix F: Acronyms

References

THE FUTURE OF THE ARECIBO OBSERVATORY: THE NEXT GENERATION ARECIBO TELESCOPE

Executive Summary

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 Sci

ence, 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.

In the following sections of this summary, we describe the key scientific objectives and novel

capabilities that the new facility will offer to the three science areas and space weather forecasting,

a unique new interdisciplinary application.

Planetary Science:

5 MW of continuous wave transmitting power at 2 - 6 GHz,

1-2 arcmin beamwidth at these frequencies, and increased sky coverage.

Atmospheric Science:

0° to 45° sky coverage from zenith to observe both par

allel and perpendicular directions to the geomagnetic field, 10 MW peak trans

mitting power at 430 MHz (also at 220 MHz under consideration) and excellent

surface brightness sensitivity.

Astronomical Science:

Excellent sensitivity over 200 MHz to 30 GHz frequency

range, increased sky coverage and telescope pointing up to 48° from zenith to

observe the Galactic Center.

THE FUTURE OF THE ARECIBO OBSERVATORY: THE NEXT GENERATION ARECIBO TELESCOPE

Planetary Radar Science

A key role of the LAT as the host to the world’s most powerful radar system was to character

ize 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 character

ization and orbit determina

tion of up to 90% of pos

sible asteroid impactors

Study the surface and

sub-surface of ocean

worlds around Jupiter, Sat

urn and other Solar System

objects

Observe asteroids in the

outer regions of the main-

belt and beyond

Space Situational Aware

ness (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

THE FUTURE OF THE ARECIBO OBSERVATORY: THE NEXT GENERATION ARECIBO TELESCOPE

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, tempera

tures, 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 contribu

tions 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. In

creased 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 per

turbations in the ionosphere

Understand interactions

in Earth’s atmosphere in

the northern and southern

hemispheres

Investigate coupling

between Earth’s atmo

spheric 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

observation

THE FUTURE OF THE ARECIBO OBSERVATORY: THE NEXT GENERATION ARECIBO TELESCOPE

Radio Astronomy

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 Long 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 emis

sion mechanism, and propa

gation of radio waves in the

interstellar medium

Gain new insights into the

causes and physical pro

cesses 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 distribu

tion of matter to moderate

redshifts to constrain Dark

Energy

Probe Extreme

Astrophysical Regimes

with Very Long Baseline

Interferometry

Detect the fingerprints of

prebiotic molecules in our

Galaxy and beyond

Detect and study Gravi

tational Waves using pulsar

timing

Explore the star formation

history of the Universe by

observing

CO emission

from massive galaxies at

redshift > 3

Study the formation of

massive stars through am

monia observations

Search for

Technosignatures from

advanced life forms

THE FUTURE OF THE ARECIBO OBSERVATORY: THE NEXT GENERATION ARECIBO TELESCOPE

Interdisciplinary science - Space Weather Studies

The US “space weather preparedness” bill [116th Congress Public Law 181 (10/21/2020)] em

phasizes the importance of space weather research and forecasting efforts. It is important to ef

ficiently 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 ex

tended 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 atmo

sphere and the near-Sun

environment

Perform high frequency

and spatial resolution

observations of solar radio

bursts associated with pow

erful 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, 2.3 times larger declination 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 Planetary and Atmospheric investigations.

We summarize the new capabilities and direct applications of this facility in Table 1. The new tele

scope 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 require

ments for the aforementioned science objectives.

THE FUTURE OF THE ARECIBO OBSERVATORY: THE NEXT GENERATION ARECIBO TELESCOPE

Table 1: The principally new capabilities and signi

fi

cant technical improvements of the

proposed concept and their impacts on the science studies.

New NGAT Capability

Comparison with legacy

Arecibo Telescope (LAT)

Enabled/Improved

science

Structural and

Instrumental

Improvements

High sensitivity

(Gain > 18 K/Jy)

1.8 - 3.6 times more

sensitive from 0.3 to 10 GHz

All

fi

elds of science en-

hanced by increased sen-

sitivity,

fi

eld of view, and

frequency coverage

Large sky coverage; zenith

angle range 0

- 48

2.3 times declination cover-

age increase (5.5× increase

in sky coverage)

All

fi

elds of science ben-

fi

t from increased sky

coverage

Beam Width of each dish

~6 deg. at 0.3 GHz

~3.5 arcmin at 30 GHz

~500 times increase in FoV

All survey observations

immensely bene

fi

t from

increased

fi

eld of view

Frequency coverage from

~200 MHz to 30 GHz

A factor of 3× more

frequency coverage

Enhanced spectroscopic

capabilities, crucial for

Space Weather studies

High survey speed

Improved and New

Capabilities

Pulsar, FRB, and spectro-

scopic surveys at various

frequencies

Capable of mitigating radio

frequency interference (RFI)

through phased nulling

Improved and New

Capabilities

All observations bene

fi

from RFI mitigation

Dual observing modes as a

phased array and interfer-

ometer

Improved and New

Capabilities

Improves HI intensity

mapping,

Detecting and monitoring

Coronal Mass Ejections

Improved

Transmitting

Capabilities for

Planetary Radar

and Atmospheric

Sciences

5 MW of continuous wave

radar transmitter power at

2 - 6 GHz

A factor of 5× more power;

maximum transmitter power

was 900 kW at 2.38 MHz

Planetary defense: 90% of

the virtual impactors can

be tracked

New space situational

awareness capabilities

and space mission sup-

port

Radar of surfaces and

subsurfaces of icy worlds

10 MW peak transmitter

power at 430 MHz (also at

220 MHz under consider-

ation)

A factor of 4× more power

ISR studies: Better spatial

and temporal resolution

to study small-scale iono-

spheric structures, natural

or human-caused, to un-

precedented levels

For the con

fi

guration given in Table 2a on page 38.

THE FUTURE OF THE ARECIBO OBSERVATORY: THE NEXT GENERATION ARECIBO TELESCOPE

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 cancella

tion system, an active project in development at the AO location. Several other advantages for the

Arecibo site include:

Advantages of Arecibo, Puerto Rico as a site

Scientific

•

The proximity to equatorial

latitudes is ideal for observing

Solar System objects.

•

The location uniquely enables

ISR studies both parallel and

perpendicular to the Earth’s

magnetic field lines.

•

The geographic and geomag

netic location provides unique

latitude coverage which is not

offered by other facilities in the

world.

•

It is a strategic location from

which to study the effects of

the South Atlantic Magnetic

Anomaly (SAMA) in the Ca

ribbean upper atmosphere as

well as on the trans-ionospheric

radio signals.

•

The location is critical for

studying acoustic and gravity

waves generated by extreme

weather systems approaching

the U.S. and Caribbean.

Socioeconomic

•

To serve the population of Puerto Rico by inspiring

and educating new generations while contributing to

the socioeconomics of the island.

•

To take advantage of the existing infrastructure, which

is on federal property, and has the local government

support, significantly offsetting costs.

•

To leverage the strategic location in the Caribbean Sea,

a region with the largest traffic vessels and for which

accurate geopositioning is critical, and the ISR inputs

for space weather forecast models are crucial.

Technical

AO is located in a Radio Frequency Interference

(RFI) Coordination Zone which minimizes the effects

of RFI, protecting the radio bands needed for science

operations.

Legacy

To extend and further strengthen the ‘long-term

legacy’ ionospheric data for future climate change

investigations.

THE FUTURE OF THE ARECIBO OBSERVATORY: THE NEXT GENERATION ARECIBO TELESCOPE

Contents of the white paper

This white paper was developed in the two months following the collapse of LAT through discus

sions 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 con

struct 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 capabili

ties 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.

Additional science studies that are enhanced by new NGAT capabilities

C.1 Additional Planetary Science Studies including

•

Radar of comets

•

Spectroscopic studies of comets and interstellar visitors

•

Additional missions for spacecraft support

C.2 Solar Wind and Space Weather Studies including

•

Tracking Coronal Mass Ejections (CMEs)

•

Faraday Rotation and the internal magnetic field of CMEs

•

Solar Radio Studies

•

Solar Wind and Space Weather Impacts on the AIMI System

•

In-situ Data Comparison and Cometary Plasma Tail Investigations

C.3 Pulsars Studies including

•

Wide searches for

◦

new pulsars

◦

Binary pulsar studies

•

Pulsar emission mechanism and individual pulses

C.4 VLBI Studies including

•

General Relativity field tests

•

Applications to Stellar Physics

•

Observations of Extragalactic Continuum Polarization

C.5 Radio Astronomy at high frequencies

•

Probing the nature of early and late-type stellar evolution from the

local to the distant Universe

•

Pulsars and Transients at high frequencies

THE FUTURE OF THE ARECIBO OBSERVATORY: THE NEXT GENERATION ARECIBO TELESCOPE

Other Science Activities at the Arecibo Observatory that interlock with NGAT

C.6 A Comprehensive Snapshot of the Galactic plane

C.7 Further discussion of Near-Field HI 21 cm Line Cosmology

C.8 Detection of Cold Dark Matter and Testing the Standard Model of

Particle Physics

C.9 Additional Space and Atmospheric Science studies

•

Ion-Neutral Interactions in the Atmosphere

•

Sudden Stratospheric Warming Events

•

Plasmaspheric studies and modeling

•

Inter-hemispheric flux of particles and its impacts on the Caribbean

Sector

•

Atmosphere-ionosphere-magnetosphere interactions (AIMI)

•

Vertical Coupling of the Earth’s atmospheric layers

◦

Science driver for the NGAT 220 MHz Coherent Radar

◦

Wave energy in the F-region thermosphere

◦

Climatology, morphology and equatorward propagation of MS

TIDs

◦

Tropospheric Forcing on the upper atmosphere during Extreme

Weather Systems

◦

Aerosol and Coupling Processes in the Lower Atmosphere

D.1 Complementary Space and Atmospheric Science studies

•

Ion Transport processes using Lidars and ISR

•

Climate Studies and Forcing of the Ionosphere from below using

LidarsGeocoronal hydrogen: Secular change and storm response

•

Horizontal winds as a function of altitude: New wind measurements

above the exobase

•

The AO Remote Optical Facility (ROF) in Culebra Island

◦

High Doppler resolution measurements of vertical motion in the thermo

sphere

◦

Field line diffusion of HF produced electrons as a function of energy

◦

First Caribbean Meteor Radar and its application to enhance the atmo

spheric probing

D.2 12m Telescope for radio astronomy

D.3 e-CALLISTO spectrometer

E. Planetary subsurface studies with 40-60 MHz radar observations.

THE FUTURE OF THE ARECIBO OBSERVATORY: THE NEXT GENERATION ARECIBO TELESCOPE

1.0 Introduction

The Arecibo Observatory (AO) is a multidisciplinary research and education facility that is rec

ognized worldwide

as an icon to astronomy, planetary, and atmospheric and space sciences. The

hosts multiple radio and optical instruments onsite a

s well as

a Remote Optical Facility (ROF)

in Isla Culebra.

AO’s cornerstone research instrument was the

William E. Gordon telescope,

ferred

in this document as the legacy Arecibo Telescope (LAT). This telescope,

completed in 1963,

was a 305-meter spherical reflector dish built into a natural sinkhole of the karst topography near

Arecibo, Puerto Rico. The optics to correct for spherical aberration, radar transmitters, and radio

receivers to cover multiple frequency bands were housed in the Gregorian dome, suspended on a

platform 150 meters above the dish.

For over 57 years the

has led in scientific research and discoveries. Among the many pro

found achievements enabled by the

L AT

, we highlight here the discovery of binary and millisec

ond pulsars, the first detection of exoplanets, the determination of Mercury’s rotation period, and

more recently, the telescope’s critical role towards the detection of long-wavelength gravitational

waves, and the characterization of asteroids for NASA mission support and planetary defense

purposes. To date, the data collected at AO

- generated

from

over

1,700 observing proposals from

the scientific community

- has

resulted in

more than

3,500 scientific publications, 376 masters and

PhD theses, 1,000 student STEM projects, and a number of prestigious awards including the 1993

Nobel Prize in physics, the Henry Draper Award, and the Jansky Lectureship

in 2020

On August 10, 2020, an auxiliary cable that supported the

L AT

’s 900-ton platform experienced

a failure, resulting in damage to the telescope’s primary reflector dish and the Gregorian dome. In

the following weeks, structural models were developed for the platform, towers, and suspension

cables so that the appropriate temporary and permanent repair plans could be developed. On No

vember 6, 2020, before the temporary repair efforts could be implemented, a main cable connected

to the same tower unexpectedly snapped, possibly as a result of bearing the additional weight due

to the loss of the auxiliary cable. Following the second failure, two of the three commissioned

engineering reports recommended a controlled decommissioning of the telescope. Based on this

report, the National Science Foundation announced on November 19, 2020 that the telescope

will

be decommissioned. However, on December 1, before the controlled decommissioning could be

executed, the remaining cables attached to the same tower failed, causing the collapse of the plat

form into the 305-m receiver dish below, irreparably damaging the telescope.

In the three weeks following the collapse, AO’s scientific and engineering staff and the AO us

ers community initiated extensive discussions on the future of the observatory. The community is

in overwhelming agreement that there is a need to build an enhanced, next-generation radar-radio

telescope at the AO site. From these discussions, we established the set of science requirements

the new facility should enable. These requirements can be summarized as (see also Executive

Summary) 5 MW of continuous wave transmitter power at 2 - 6 GHz, 10 MW of peak transmit

ter power at 430 MHz (also at 220 MHz under consideration), zenith angle coverage 0 to 48 deg,

frequency coverage 0.2 - 30 GHz and increased FoV. These requirements determine the unique

specifications of the new instrument.

The telescope design concept we suggest

consists of a compact array of fixed dishes on a tilt

able, plate-like structure that exceeds the collecting area of the LAT.

This concept, referred to

throughout this text as

the Next Generation Arecibo Telescope (NGAT),

meets

all

of the desired

specifications and

provides significant new science capabilities to all three research groups at

AO.

We discuss the specifics of this unique concept in Section 3.

THE FUTURE OF THE ARECIBO OBSERVATORY: THE NEXT GENERATION ARECIBO TELESCOPE

2.0 Key Science Goals

We delineate in the following section the key science goals of NGAT. These science goals were

the drivers for the capabilities of the new concept described in Section 3. In order to better discuss

these objectives in the context of the new, unparalleled capabilities, we first illustrate the new pa

rameter spaces NGAT will open up. As shown in Fig. 1 (divided in four panels below), the NGAT

will have a field of view 500 times larger than the LAT and 3 times more frequency cover

age. It will also have 2.3 times more declination coverage, more than 4 times the radio signal

transmitting power, and nearly double the sensitivity to receive radio signals when compared

with the LAT.

Figure 1a.

Comparison of the sky coverage (see also Appendix C.3, Fig. 15) of NGAT with the legacy Are

cibo telescope (LAT).

Figure 1b.

Comparison of the telescope gain of NGAT

with the LAT. The NGAT covers a frequency range

from 200 MHz to 30 GHz, which is 3 times larger

than that of the LAT. The system temperature above 10

GHz was estimated using the ATM model (Pardo et al.

2004; Luca Olmi, private communication).

Figure 1c.

Comparison of the field of view

NGAT with the LAT.

For the configuration summarized in Table 2a