Planetary science, and the field of Near Earth Asteroids in particular, lost one of our most brilliant scientists and devoted friends with the death of Steve Ostro on December 15, 2008. During the 1980s, Steve reinvented the field of radar astronomy, showing the incredible results that could be obtained with the new, powerful radar telescopes at Arecibo (Puerto Rico) and Goldstone (California). I first met Steve in the context of trying to understand the anomalous radar signatures of the icy satellites of Jupiter: Callisto, Ganymede, and Europa. Most readers of NEO News, however, will think of Steve primarily as the originator of radar studies of near-Earth asteroids, not only to measure their orbits with exquisite precision, but also to provide images of astounding resolution and beauty. Who can forget Steve's pictures and models of Castalia, the binary asteroid that seems to be composed of two bread-buns rotating in contact, or Toutatis, the 5-km-long contorted object that is among the largest NEAs that could someday hit our planet. Steve was passionate about radar science, but also about the importance of protecting the Earth from impacts. Many times he said, with his characteristic blend of a big smile but forceful delivery, that all we needed for political support was to show the public these images, to let them see that NEAs were real, so they could recognize at an intuitive level that we do not want to collide with them. In addition to brilliant science and inspiration for a new generation of radar astronomers, Steve's legacy includes the public and political awareness today of the reality of the impact hazard.
Following are several obituaries and tributes from Steve's fellow planetary scientists.
Sky & Telescope: Steven J. Ostro (1946-2008)
Posted by Kelly Beatty, December 18, 2008
We received word this week that Steven J. Ostro, a pioneering radar astronomer at the Jet Propulsion Laboratory, died on December 15th after a two-year fight with cancer. He was 62.
The worldwide community of planetary scientists has grown tremendously since I started covering the solar-system beat in the mid-1970s, and a great many of them are friends. So too was Steve. He and I crossed paths in the mid-1980s, not long after he joined JPL's planetary-radar group. Steve basically invented the technique of using powerful radar antennas to probe asteroids, beginning with a successful "ping" of the main-belt heavyweight 1 Ceres while a graduate student at MIT.
Steve realized radar's potential not only for determining the surface characteristics of small rocky bodies but also for pinpointing their line-of-sight distance and velocity with incredible accuracy. Guided by his skill at wringing absolutely every bit of information from a radar echo, both of these capabilities became powerful analytical tools in the effort to understand near-Earth asteroids and the threat they pose to Earth.
Over time Steve and radar scientists he trained racked up hundreds of successful asteroid "hits" with the NASA dish and the even larger Arecibo radio telescope in Puerto Rico. They're all tallied on the informative website that Steve maintained to chronicle his team's work.
One encounter I'll never forget took place in August 1989, when I headed west to cover Voyager 2's historic flyby of Neptune. As it happened, a small Earth-crossing asteroid designated 1989 PB had been discovered just a week beforehand, and Ostro intended to use NASA's giant tracking antenna in the Mojave Desert - a couple hours' drive from JPL - to try to record the interloper.
After driving in predawn darkness to reach the facility, I met him at the base of the gargantuan antenna. The gleaming-white dish is 210 feet (70 m) across, and it looks a lot bigger in person than it does in photos. Steve took the time to give me an insider's tour that culminated with climbing onto the towering feedhorn. Once he'd completed his observing run, it became clear that the asteroid (later numbered and named 4769 Castalia) was a contact binary - a double-lobed body joined by a narrow waist of rubble.
I'll remember Steve as a study in contrasts. On one hand, there was a quiet intensity about him, even in friendly conversation, yet he had a powerfully persuasive style of lecturing that commanded your attention. And although he enjoyed having the fruits of his observations promulgated to a wide public audience, Steve notoriously guarded his findings until he felt the conclusions were rock-solid and beyond reproach.
"I feel extremely fortunate to be doing this work," he said in 2003, on the occasion of receiving a lifetime-achievement award from his planetary-scientist peers. "It's like a Star Trek fantasy - seeing a world that no one has ever seen before. That's what I've been able to do over and over."
Planetary News: Steven J. Ostro, 1946 - 2008
By Charlene Anderson, The Planetary Society
December 16, 2008
The Planetary Society has just lost a good friend and valued colleague: astronomer Steven J. Ostro died early in the morning of December 15, 2008. The world has lost one of the most skilled scientists tracking and studying the asteroids that pass close by our planet - and might one day threaten the survival of our civilization.
Steve was a radar astronomer -- not your garden-variety astronomer who makes passive measurements of reflected sunlight or naturally emitted radiation. Radar astronomy is active -- just like Steve was himself. Radar astronomers send radio transmissions to hit moving targets, then measure the characteristics of the echoes received back on Earth. From those measurements, they can deduce the shape and motions of an asteroid, and whether it is a solid rock or a loosely bound pile of rubble.
The Planetary Society got involved with near-Earth asteroids in the early 1980s, beginning with our support for the pioneering discoveries of Gene Shoemaker and Glo Helin at Palomar Observatory. Steve joined JPL in 1984 and headed the asteroid radar group. In 1989, he and his team used the great, 300-meter dish of the Arecibo Observatory to image an asteroid, 4769 Castalia, for the first time.
The combination of a superb instrument - the Arecibo antenna - and a passionate scientist - Steve - produced amazing results, including the observations that were used to confirm that 99942 Apophis will not collide with Earth when it passes under the orbits of geosynchronous satellites in 2029.
And then there was 1999 KW4 -- a bizarre astronomical object by anyone's appraisal. On its path about the Sun, it crosses the orbits of Mercury and Venus, then approaches Earth's orbit - with the potential to someday collide with our planet. Fortunately for those of us alive today, Steve's observations have shown that a collision is unlikely for at least the next thousand years.
Even while the Arecibo Observatory was proving its worth in precise tracking of those asteroids that might threaten Earth, budget cuts and internecine government-agency wrangling threatened to shut it down. With his best instrument threatened, Steve turned to The Planetary Society for help and our members responded, bombarding their congressional representatives with demands that Arecibo be kept open and sending their Society representatives to testify to the U.S. Congress in support of the observatory.
It was impossible to resist Steve's intense passion for his work, and when this morning I learned of his death, I went quietly down to the shelf on which the 1999 KW4 model was displayed and brought it up to my office. It's sitting on my desk, in all of its mud-ball splendor, as I write this. Remembering Steve, and looking at his asteroid model, I can truly appreciate its beauty.
DPS: Steven Ostro, In Memoriam
We are very sorry to report the news that pioneering JPL radar astronomer Steve Ostro died early on the morning of Monday December 15th. The following appreciation is based on a note sent by Bonnie Buratti to Steve's Cassini colleagues:
Steve was a luminary in the field of Radar Astronomy, and received the DPS Kuiper prize in 2003 for his groundbreaking work in asteroid and satellite radar studies. Steve's seminal work on the surface properties of the Galilean satellites-which he was extending to the Cassini Radar data he was gathering and analyzing up to a few days before he died-led to the development of new models to explain how electromagnetic radiation interacts with ice. He and his colleague Lance Benner almost single handedly established the field of radar studies of Near Earth Objects. Steve received his PhD from MIT in 1978 under Gordon Pettengill and Irwin Shapiro. He was a professor of Astronomy at Cornell University before coming to the Jet Propulsion Laboratory in 1984, where he established the radar astronomy group. Steve gave of his time freely to younger colleagues and students. His collegiality and intellectual honesty will be missed. Steve died of pneumonia after a silent and courageous battle with cancer. He leaves his wife of 40 years, Jeanne Ostro, and three children.
I always take it for granted that each of us is going to live forever. I am heartbroken. But I am also full of the fondest memories. Steve, you have been such a mentor in so many ways to us all, and there is nothing I would rather do than have another one of those philosophical and delightful dinners in your back yard with you and your family and close friends.
- Erik Asphaug
I was very sorry to hear of Steve Ostro's passing. I have two memories of him that I'd like to share. The first took place during the mid 1980s, when Clark Chapman and I shared a few nights on Kitt Peak studying asteroid rotation periods. On one of these nights Steve Ostro joined us. It was a memorable night, a hell of a lot of fun, and the best chance to get to know him. Years later I wrote about him for my column, which then appeared in Sky & Telescope magazine. When I interviewed him at that time he still had the quiet, soft-spoken intelligence that was his hallmark, I thought. He was a true founder of the still nascent-field of radar astronomy, and he has used it well. I will miss him greatly.
- David H. Levy
Steve was a great scientist, he started a new, fundamental field of research, but apart from that I will personally remember him for his courtesy. For some strange reasons that I do not fully understand, the memory of him greeting me when meeting me the first day of some DPS meeting several years ago (perhaps in Cornell) and introducing me to some other people who were present in that moment, has remained in my memory as an example of great courtesy that touched me. I think that it is the hope of everybody to leave in the memory of other people some good feeling, that can sometimes be produced even by minimal facts. Steve succeeded with me. I will miss him as a scientist and as a person.
- Alberto Cellino
Thank you, Steve, for your enthusiasm, your support, and your great work. You inspired us with your passion for radar astronomy and for understanding our smallest celestial neighbors. You challenged us to explain what you were discovering. You gave freely of your work (how many of us have those cool asteroid models??). I personally owe a lot of my research to your efforts and those of your colleagues. You were a champion for Arecibo and radar astronomy in general. Above all you were a generous and caring person. You will be missed.
- Derek Richardson
I am terribly saddened by the loss of Steve Ostro. We have been friends for over 25 years and I always marveled at his intensity and his total dedication to the work he was doing. He is one of the best scientists I have ever known and his advancement of radar astronomy in the solar system is an incredible achievement that we are all the better for. He was also a great friend with a wry sense of humor that I will miss in the years to come. I talked with him when his cancer reappeared earlier this year and his concerns were not for himself but rather for his family and how they would manage without him. As his colleagues we will also have to manage without him, but we can be grateful for the time he was here and the incredible legacy of work he left for us.
- Paul Weissman
Steve taught me much over the years, appreciation of fine wines and food in addition to science. In one early co-authored paper, combining radar and lightcurve results, he complained of my lightcurve analysis, "this isn't science, it's witchcraft!" thereby forcing me to improve my methods to develop a Fourier analysis algorithm that is now used for analysis in around 100 papers a year. Certainly the inspiration and much of the credit goes to Steve. In October, I submitted a paper to Icarus, with the following dedication, remembering his demand for rigor in science: ?We dedicate this paper to our friend and colleague Steven J. Ostro. Ostro has pioneered the field of radar astronomy, particularly in exploring Near-Earth Asteroids and the methods of inversion of both radar and optical data to obtain shape models of irregular bodies. Without such tools we would not have detailed images of asteroids and binary systems that provide the essential input for the modeling in sections 2 and 4 of this paper. Anyone who has co-authored a paper with Steve is aware, sometimes painfully so, of his insistence on rigorous analysis, and that it is at least as important to explore and define what one can't say from the data, as it is to present what one can say. It is in this spirit that we present section 3 of this paper.?
- Alan W. Harris
I got to know Steve when I took a faculty fellowship at JPL in the summer of 1999, specifically to work with him. He had reputation for brilliance and for not suffering fools, and it was with some trepidation that I began that summer. I quickly found him to be an incredibly polite and disarming man, and he and his wife Jeanne welcomed my family to the area with a lovely afternoon at their home. He was a terrific mentor and I learned well, sometimes painfully as others have noted, from Steve's insistence on rigor, realistic error analysis, and tight prose in his publications. But when the final draft was done and Steve put his name to it, you could have confidence that it was well written, thorough, and as close to the truth as it was possible to get with the data in hand. It was a great privilege to know and work with Steve, and I am better for it.
- Mike Shepard
I would like to join my appreciation of Steve to those of my colleagues across the world. I had the privilege to share for a couple of years the same office with Steve Ostro in the department of Earth and Planetary Sciences at MIT where I was preparing my Ph.D in radar astronomy in his footsteps. Steve was an extremely dedicated scientist putting seriousness and integrity in everything he was doing. I am greatly indebted to him for his contributions to the radar astronomy software I used for the observations and data interpretation of the first detections of cometary nuclei, in 1980 of P/Encke and in 1982 of P/Grigg-Skjellerup. We also exchanged in details on the improvement of the accuracy of the data interpretation. Since we both left MIT I never missed an opportunity to visit Steve when I visited JPL and I still keep preciously in my office the 3D model of asteroid Golevka that Steve gave me. I send my deep regards to his wife Jeanne and his children: I will always remember how he talked to me about them with love and admiration.
- Paul Kamoun
I will remember Steve most for his gracious heart and kind words; he was a supportive presence throughout my graduate career, continually encouraging and constructively praising. He was impressive in his sharp intellect and his expressive, well-chosen words, but never overbearing. I felt that I could approach him with any problem, and he would offer insightful advice with a pleasant demeanor. I never failed to walk away from a talk or speech by him without marveling at how clearly and cohesively it was delivered. His positive outlook together with his high standards will be a model for me always. I will remember him as he was when I first met him 5 years ago, and how he was when I last met with him, less than two months before his passing. Even facing down death and encumbered by his weakened body, his mind was as sharp and focused on the task as always, his spirit both resilient and accepting. While he was dedicated to great science up until the end, he was, at the same time, never wavering in his humanity and kindness. Thank you Steve for showing me how it's done.
- Lauren Wye
As a post-doc, I remember sitting down with Steve more than once at DPS meetings and asking him to explain his process, procedures and interpretations of his data. I have never worked with radar data, but he explained things so clearly, that I think I get it. The radar reflectivity of the Galilean satellites was a baffling phenomenon at the time, I remember his saying that he didn't understand it. A few years later, I realized that his work on asteroids was equivalent to flyby missions. The knowledge derived from each asteroid studied by radar, is basic knowledge of their size, shape, rotation and characteristic of their surface. That's what we determine from an asteroid flyby mission. I told him that many times, and I felt that I was admiring his work when I said it. It never made sense to me that his work was threatened by facility cuts. At one meeting, Steve reached into his pocket and handed me a 3D model of asteroid Toutatis, he smiled and said, here, you should have this. I was honored. While he was sick, Steve revised the chapter on Radar Astronomy in the Encyclopedia of the Solar System and helped me get the files needed to make a 3D model of comet Tempel 1 made. In summary, I admire Steve's science and the research team he has developed. He was a charming person and always friendly. I will miss him. My heart goes out to his close colleagues and family.
- Lucy McFadden