Executive Summary

Overview

In 2003, the University of Arizona (UA) and the National Optical Astronomy Observatories (NOAO) began their partnership as part of the NASA Astrobiology Institute (NAI). Much of the activity in the first six months of the funding period has been spent in starting up programs and instituting collaborations within and between the two organizations and with other entities. First postdoctoral workers are starting to arrive, and equipment is under construction. Those activities that have made most progress are those in which least preparatory activity was required. Good progress is underway in all areas including observational, experimental and theoretical work.

The Arizona NAI team is strongly focused on the astronomical activity needed to support astrobiology. We have three research modules. The first is “Building blocks of life", which asks the question: which molecules are present in potentially pre-planetary space, and therefore might become available for the origin or development of life? We are developing equipment to determine the laboratory spectra of complex organic molecules that are potentially important to the origin of life, so that searches can be made for them in space. We are continuing astronomical searches at millimeter (mm) and sub-mm wavelengths for spectral features of sugars and other pre-biotic molecules in star-forming environments analogous to conditions that may have given rise to our solar system. We are developing experiments in gas phase chemistry to explore the gas phase polymerization of formaldehyde to more complex sugars, and we have initiated quantum mechanical calculations to explore gas phase processes that might lead to pre-biotic molecules. These molecules can arrive at a young terrestrial planet either by accretion in a preplanetary disk or as material incorporated in the infall of comets or planetesimals. This module is also searching for these molecules in the spectra of comets.

Our second module, “Formation of Habitable Worlds", is concerned with the development of planets and planetary systems out of disks of gas and dust that commonly surround young sun-like stars. There are both observational and theoretical activities within this module: observing disks from the ground and space and studies of planet formation and dynamical studies of disks. Our goal in this work is to better understand the frequency of giant planet formation and the influence such planets have on the formation of terrestrial planets and their suitability for life. In this module we also include a study of the variability and magnetic activity of solar type stars of various ages. This information will be incorporated into studies of Earth climate and environment.

The third module, “Nature of Planetary Systems", is concerned with the detection of planets and the characteristics of other planetary systems. This module supports theoretical work on characteristics expected of extrasolar planets, searches for those planets, and studies of the terrestrial spectrum to understand extrasolar terrestrial planets. This last work is to assist the development of Terrestrial Planet Finder (TPF) and other means of detecting extrasolar planets. We have added to this work the development of a star list for the TPF missions.

In addition to these activities in research, we have an active program to develop our local astrobiology community by expanding our Life and Planets Astrobiology Center (LAPLACE) to include existing and new programs in astrobiology in Tucson, and especially to develop links with Life Science studies at the University of Arizona (UA).

A wide array of astrobiology-related research is ongoing in Tucson in addition to that of LAPLACE. For example the Mars Phoenix Mission is based in Tucson, and local researchers are playing a key role in the Cassini-Huygens mission to Saturn and Titan. LAPLACE is exploring ways to take maximum advantage of the physical proximity of these researchers. In addition our astrobiology-related programs are evolving and expanding to reach graduate education, international collaborations and education and public outreach to high school teachers and non-science undergraduates.

Construction of Equipment and Development of Techniques

In module 1 we are in the design and construction phase of a laboratory Fourier Transform spectrometer to obtain high precision radio frequencies enabling us to search for organic molecules in interstellar clouds, pre-planetary disks and comets. Large parts for the spectrometer are on order and the Steward Observatory machine shop has begun to produce smaller elements. The instrument is expected to be in use by the end of the year.

In module 2 we are constructing an automated telescope for the study of solar type stars. The major items for this telescope, large optical steel tube assemblies, are nearing completion. Researchers will initiate observations by the end of this year.

In module 3, we have two construction projects. Close and Biller completed their first observations using simultaneous differential imaging in two spectral bands near 1.6 microns. The technique is able to suppress speckle noise by using a methane spectral feature that occurs in planetary (or faint brown dwarf) companions, but not in the light of the central star. The technique has enabled a very large improvement in primary to secondary contrast. A first survey of the youngest stars that might host bright giant planets has been made in Chile, and data are being analyzed. The technique is now being used with the 6.5-meter MMT in Arizona to search for companions to nearby stars.

Freed and Hinz are constructing a second instrument, a 5-micron imager (Klio) for use with the infrared optimized adaptive optics system of the MMT. This instrument is nearing completion, and test observations are planned for Fall 2004.

Laboratory and Telescope Observations, and Development of Observation Plans

In module 1, graduate student Halfen’s observations of 25 rotational transitions with the 12-m telescope at Arizona Radio Observatory have confirmed the identification of glycoaldehyde in the interstellar medium from which stars and planetary systems form. This detailed process is necessary for the identification of complex molecules, and it has served as a preparatory program for future surveys to find more complex molecules.

Graduate student Milam has observed formaldehyde in three new comets and HCO⁺ in comet Hale Bopp. Some of the evidence suggests that mm-sized particles containing these molecules break off, and could be swept up by planets (Milam, Savage, Ziurys and Wyckoff, in press).

Werner and Judd are exploring the gas phase polymerization of formaldehyde to make more complex sugars in the laboratory. A series of experiments for necessary technique development are in progress.

In module 2, Meyer et al . have submitted the results of their first observations of disks around solar type stars observed with the Spitzer Space Telescope (SST). The results suggest that there is not a unique correlation between the age of the disk and the emission by its dust. Stochastic processes of asteroid collisions are one possible cause. Supporting work has been carried out in collaboration with graduate student Mamajek. They find that circumstellar disks in the terrestrial planet zone (0.1 to 10 AU) dissipate within 30 Myr (Mamajek et al. , in press). Meyer has also initiated a program to explore the relationship between stellar rotation and the presence or absence of circumstellar disks. Under the supervision of Hinz, Liu and collaborators have used the technique of nulling interferometry to resolve the circumstellar disk around the intermediate mass young star HD100546.

Najita (with Gorti, Hollenbach and Carr) has been awarded SST time to search for gas in circumstellar disks around very young stars. Najita, Strom (and Richter) have also been awarded observing time on the Infrared Telescope Facility (IRTF) on Mauna Kea to develop techniques for observing circumstellar atomic and molecular gas. In addition Najita was awarded observing time at the Keck telescope for detecting and characterizing circumstellar gas.

In module 3, using the Vatican Advanced Technology Telescope (VATT) at Mt. Graham International Observatory, the first observations have been made of earthshine in the near infrared and the data reduction will be part of Turnbull’s Ph.D. thesis. This spectral region is potentially important for studying terrestrial planets. It contains stronger water bands than the visible, and this could be significant for studying cold terrestrial planets. It also contains bands of carbon dioxide, from which a quantitative measure of abundance can be made, and the most easily observed band of methane, which is important for a Life Finder mission.

Figure 1: The near infrared albedo spectrum of the Earth obtained from earthshine measurements at the Vatican Advanced Technology Telescope at Mt. Graham International Observatory. From left to right the bands are: Oxygen A band 7600A, Water 8300A, Water 9400A, Water 11300A, Oxygen 12700A, Water 13800A, Water 18700A, Carbon dioxide 20000 and 20600A and Methane 22000A.

Theoretical Studies

In module 1, Adamowicz and Bednarz have started to use quantum mechanical calculations to investigate the processes leading to simple sugars. The first part of the project is to model stationary states and dynamical behavior of molecules and molecular ions, and the development of new algorithms and computer software is underway.

In module 2, Lunine has worked with Raymond and Quinn (University of Washington) to develop models of terrestrial planet formation, to explore the masses of the predicted planets, and the content of volatiles such as water. Studies of systems resembling the solar system typically yield one to four terrestrial planets, and they have a variety of water contents and eccentricities that seem determined by the giant planet characteristics. In planetary systems where a “roaster" Jovian planet had formed early, close to the star, they find that terrestrial planets can form with amounts of water similar to Earth, but formation of terrestrial planets is suppressed overall as the orbital radius of the “roaster" moves outward from 0.1 AU.

Malhotra (in collaboration with Kring, Ito and R. Strom) has been investigating the nature of the Late Heavy Bombardment (LHB) of the Moon ~3.9 Gyr. They are exploring the possibility that a large catastrophic asteroid break-up event close to a gravitational resonance was responsible for the LHB. They are modeling in detail the dynamics of such a break-up event, calculating synthetic crater records from such an event, and confronting these with the observed crater records.

Malhotra and Moro-Martin are modeling the expected signatures of planets in the mass surface density distribution of debris disks in support of observational programs. They have examined the observational consequence of such signatures in the unresolved stellar spectral energy distribution, and their dependence on the planetary and debris parameters.

Malhotra has also been studying the stability of orbits of sub-jovian mass planets She has developed a simple secular stability criterion for two-planet systems that provides strong constraints on the orbital location of sub-jovian mass planets.

In module 3, Burrows, Sudarsky and collaborators are building on their successful models of isolated planets to predict the brightness and spectra of Jovian planets around other stars. These studies are closely coupled with the plans to observe these objects.

Turnbull has used data collected to help the Search for Extraterrestrial Intelligence (SETI) project to help design searches for emission from terrestrial planets. She has worked with the TPF Science Working group to develop a list of stars appropriate to possible TPF missions.

Meetings and astrobiology development

This has been a busy year in planning new activities, and a number of them have been international in scope. In January LAPLACE hosted the first Graduate Student Astrobiology Conference in Tucson, attended by about 60 students from approximately 40 different schools, including a number from foreign countries.

In April we held a two-day meeting with physical and life science researchers, assisted by Juan Mercado of the Spanish Astrobiology Institute. Prior to the meeting we made presentations to a number of departments in the UA’s College of Science, and there was general enthusiasm for developing a much wider program than we currently have. The Planetary Science Institute (PSI) also sent a representative to the meeting, and we look forward to future collaborations with them. There was agreement for LAPLACE and life sciences to work together. As a first step the UA College of Science submitted a National Science Foundation Integrative Graduate Education and Research Traineeship (IGERT) grant proposal. This proposal focuses on the biochemical origins of life. Although they are not yet part of the LAPLACE team, UA life sciences researchers, including Nancy Moran, new member of the National Academy of Sciences, are keenly interested in working with us.

LAPLACE will be participating in the Vatican Observatory Summer School (VOSS) on astrobiology in Castel Gandolfo, Italy, in the summer of 2005. This is a joint project of the Vatican Observatory (Corbally and Coyne) and faculty from the UA (Impey, Lunine and Woolf) and the University of Washington (Baross and Sullivan). We found the polycom system to be helpful in holding a planning meeting.

Figure 2: UA, Vatican and University of Washington researchers during an April 2004 planning meeting for the VOSS. Use of the NAI polycom system aids greatly in the communication among the far-flung collaborators. Woolf, Lunine, Impey and Corbally participated from the UA campus; Baross and Sullivan participated from the Washington campus.

Chris Impey of the UA Astronomy Department is Principal Investigator for a grant from the Templeton Foundation to explore the relationship between astrobiology and religious thought. The funds will bring in speakers in science and other areas from outside UA, and be used for course development. The Templeton team includes Lunine and Woolf from LAPLACE and professors from the Vatican Observatory and UA Departments of Biology, Judaic Studies, Art, Humanities and Education. It is a promising avenue for interdisciplinary outreach.

LAPLACE has also received its first private funds for astrobiology scholarships for graduate students. These will be distributed for the first time for the Fall 2004 semester.

Teaching

We have taught a number of courses in astrobiology at UA as well as throughout the community. UA typically enrolls 100-200 students per term in the advanced Life in the Universe course for nonscience majors. Tim Slater leads the Education and Public Outreach (EPO) group. EPO held two courses Astrobiology for Teachers in Fall 2003 and Spring 2004. In Spring 2004, Meyer and Woolf taught an astrobiology course to seventeen astronomy and planetary science graduate students. In the summer of 2004 the EPO group taught a master’s level course for teachers. EPO held seven workshops for teachers in 2004.

These outreach efforts are part of an “advanced EPO" project in which our team is focused on exploring the conceptual problems encountered by students in astrobiology, and teaching at a higher level than commonly occurs in public outreach. We see this as an essential part of the process of developing broad based support for astrobiology.

Hiring of postdoctoral assistants

The hiring of postdoctoral assistants for this work began with receipt of funds in November 2003. In a few cases appropriate people were available, and they have already been hired. However in the majority of cases, the postdoctoral assistants are due to arrive at the start of the Fall 2004 semester. All available positions will be filled by year-end.