Houston - We Have a Space Conference

Oct. 19, 2002

by Seth Shostak - Senior Astronomer

You don’t have to be a rocket scientist to come to the World Space Congress, but most of those that do, are.

This week, Houston is stuffed to the seams with several thousand rocket jockeys, satellite sycophants, and space buffs of every genus and species. Engineers, scientists, space lawyers, and anyone else with a professional interest in the cosmic realms beyond Earth has descended on this sprawling Texas town, to meet, talk, and schmooze. That includes a hefty contingent of SETI folk.

Indeed, the Conference has sported two large SETI sessions, at which nearly twenty papers were thrust upon the crowds. The first covered recent technical advances in the search, while the second dealt with SETI’s societal effects and how we might decipher any cosmic communication. In deference to both this site’s column space and the busy lives of readers, I will give but a few highlights of these sessions. Future articles will undoubtedly elaborate on additional topics of interest.

The lead-off stem winder was delivered by SETI pioneer Frank Drake. Drake, who arguably has the lengthiest SETI pedigree on the planet, tried to step back from the details of today’s searches, and look at the big picture. He noted that radio SETI experiments have traditionally assumed that aliens eager to establish contact will make their presence known with narrow-band, easily detectable signals.

But in the last decade, Homo sapiens has shifted a lot of transmissions to wide-band (spread-spectrum), low power modes. This change has been driven, not by technological advance, but by social pressure. Folks just want to be in telephonic and internet touch, no matter where they drive or have dinner. A high data rate, not high signal detectability, is what’s "in" today. In another few decades, the paradigm could shift again. Drake’s point is sharp and simple: we should not limit our SETI searches to only those approaches that seem plausible in light of our current technological capabilities.

Subsequent speakers talked of plans and construction of new telescope arrays for SETI, both small and large. Paul Shuch, of the SETI League, described a phalanx of eight 1.8 meter dishes that he’s planted in the back yard of his Pennsylvania home, forming the VSA, or Very Small Array. He expects to use these satellite sisters as a proof-of-concept prototype for the League’s Array2K project, which will consist of 16 four-meter dishes. The SETI Institute’s Jill Tarter then went to the other end of the size scale, describing the proposed Square Kilometer Array (SKA), a radio telescope with 100 times the collecting area of today’s largest arrays. No one is quite sure how the SKA should be configured – with lots of small antennas or a few large ones – but whatever its construction, this mother of all radio telescopes will permit radio studies, including SETI, to sample a thousand times the volume of today’s searches. Laying the cornerstone of the SKA is expected around 2010.

Next up was Italian space guru, Claudio Maccone. For several years, Maccone has been looking at the possibility of putting radio telescopes on the far side of the moon. This is attractive not because of the low lunar real estate prices, but thanks to the fact that the moon’s hidden hemisphere is shielded from all the radio interference that wafts up from Earth. Previous work had proposed siting the lunar observatory in Saha crater, which is just beyond the moon’s limb. This would allow easy and continuous data streaming back to earth-bound scientists. But Maccone is concerned that future development of high-orbit communication satellites will soon pollute such lovely limb locations. He says that the only safe place to hide from interference is smack dab in the middle of the moon’s far side, for example in the 80 km-wide crater known as Daedalus.

Dan Werthimer, who is the principal scientist for many of the University of California, Berkeley, SETI programs, gave an impressive inventory of his work. He described projects such as SERENDIP IV and SETI@home (which is now cranking away on home PC’s at a rate equivalent to 1,000 years of computing each day). One of the exciting developments for the popular screen saver project is Werthimer’s plan to follow up on 200 of the most promising of the SETI@home signals using the Arecibo antenna in a dedicated mode. This will happen during the next few months. He also described a new distributed computing program to search the data for very short radio pulses (a millionth of a second or so.) The proposed project name says it all: Astropulse.

As a final fillip to this report, I note the presentation by physicist Mike Harris, at the Goddard Space Flight Center. For years, various folks both in and out of SETI have suggested that we should be looking for high-powered interstellar rockets. We could do so not by looking for the spacecraft directly (which would be extraordinarily difficult), but by hunting for the radiation any truly powerful rocket would produce. For example, matter-antimatter craft, (such as the Starship Enterprise) would generate a lot of gamma rays. Harris searched through data taken by the Compton gamma ray satellite observatory to see if he could find any trace of such artificial radiation sources. His conclusion – although limited – is interesting: If there are real-life equivalents of the Enterprise, they’ve not been operating within one-tenth light-year of Earth during the years 1991- 1995. Such results could eventually put some constraints on interstellar colonization efforts.

There is, as Madison Avenue likes to crow, much, much more. That’s only natural. When you get a few thousand fin fans and nozzle nerds together, there’s bound to be plenty of gritty synergy. Houston’s convention center is an exciting place to be, and all the more so when you consider that a century ago, the very idea of a World Space Congress could only exist in the realm of speculative fiction.