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THE DAILY ASTRONOMER
Thursday, September 8, 2016
Breakthrough Starshot!
Fifty years ago this very day, "Star Trek" broadcast its first episode.* The show, entitled "The Man Trap," revolved around a salt-craving, shape-shifting vampire. This program would the first of many Star Trek Episodes that spanned only three seasons. Though now considered vintage science fiction, "Star Trek" was not particularly popular through its initial run. In fact, "Star Trek" faced cancellation many times and might have been shelved much earlier had it not been for the advocacy of its most influential fan, Lucille Ball. Ultimately, even her influence proved insufficient as the Enterprise crew couldn't withstand low ratings with the same fortitude it showed when confronting Klingons. When the show finally ended, everyone involved in the production thought it something of a noble failure: a series that strove for originality, only to hasten its own demise in the attempt. (A lot like "Cop Rock.") Only in the 1970's, when the network broadcast an animated series and then started conventions did the cast realize that their "noble failure" gave birth to an entire Star Trek Universe. The show garnered tens of thousands of fans (this number has increased a mite since) and it spawned four other series, along with many feature films, enough books to devastate a hundred old growth forests, and the most lucrative merchandising this side of Harry Potter. Today, even those who've never experienced a socially awkward moment in their lives know about "Star Trek." It has, to borrow a well-worn phrase, become a strand in our cultural tapestry.
The first "red shirt."
Darnell -as portrayed by actor Michael Zaslow- was killed in the
first episode of Star Trek. Though adorned in blue, Darnell was the
first "red shirt," defined as the crew member who accompanies the important
characters down to the planet surface so as to perish almost at once, thereby
providing an opportunity for Kirk to appear bereaved, Bones to lose his temper
and Spock to raise an eyebrow.
This series seems all the more remarkable when one realizes that it pre-dates the moon landing. (The Eagle set down about seven weeks after the last original Star Trek episode was broadcast.) Also, the show about a crew of astronauts exploring other worlds ended almost a quarter of a century before astronomers started to discover exo-planets. The first Trekkies who beheld the night sky knew of no worlds beyond Pluto, apart from those conjured by the imagination. Today, we admire a sky both for its stars and the myriad planets scattered among them. Astronomers have detected thousands of these worlds and estimate that our galaxy alone could harbor as many as one trillion planets, more than ten million of which might be similar to Earth. If these estimates are in any measure accurate, our galaxy might be teeming with life: in forms and varieties far beyond the reckoning of even the more prodigiously creative science fiction author. Unfortunately, even though our knowledge of the galaxy has increased dramatically since we first heard, "Damn it, Jim, I'm a doctor not a stone mason," we seem no closer to actually joining the galactic soiree, ourselves. Thus far, we've only sent people to the moon and even our most distant probe, Voyager I, is only 12.6 billion miles from the Sun,which is just around the edge of the heliosphere. The closest star system, Alpha Centauri, is 25 trillion miles away: about 1980 times farther from the Sun than Voyager I! One might think that many centuries will elapse before we finally deploy emissaries to the stars.
But, wait!
(And, yes, we knew you knew that whole thing was a set up)
Earlier this year, on April 12th, to be precise, venture capitalist Yuri Milner and acclaimed cosmologist Stephen Hawking announced the inception of "Breakthrough Starshot," a program designed to convey a fleet of light sail space vessels to the Alpha Centauri system. Light sail vessels are lightweight sails that take advantage of solar radiation pressure. The radiation propels the sail forward and, as the sail travels unimpeded within the vacuum, gradually, but continuously accelerates to ever higher velocities. Engineers could even focus laser beams on the sail to impart a greater boost to the sails. Although the radiation pressure diminishes greatly with increasing distance from the Sun, the sails could conceivably attain high speeds prior to departing the solar system and then would maintain those speeds during the journey to Alpha Centauri. According to some calculations, the Breakthrough Starshot sails could reach velocities of 15-20% the speed of light (37,200 miles per second). At such a velocity, the sail might require only 20 - 35 years to reach Alpha Centauri: well within the lifetimes of the mission scientists responsible for its construction.
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A solar sail: An artistic depiction of a solar sail attached to a probe. Such a sail would be propelled forward by solar radiation pressure. As the sail travels through a vacuum,it could attain ever higher velocities, and could reach 15-20% light speed as it travels to the Alpha Centauri system. Image by Kevin M. Gill, Nashua, NH
The idea is to construct about a thousand little sails that could be propelled to high speeds by lasers. Each sail would contain a probe designed to survey the planets in the Alpha Centauri system. Astronomers suspect that Alpha Centauri contains more planets than they've found, including the Earth-like planet recently discovered around the system's smallest member, Proxima Centauri. This solar sail armada would fly through the star system much like the New Horizons probe zoomed by Pluto. The probes would then direct their data back to Earth, which would arrive a bit more than four years after transmission, since Alpha Centauri is 4.3 light years from us. Were this mission to succeed, humanity would see the planets within another star system up close
Of course, the project is still in its embryonic stages. (Actually, pre-embryonic. Its parents have just realized there's nothing on the tele and, blast, its raining out, so never mind the evening walk.) Breakthrough Initiatives, the organization responsible for this program, has $100 million dollars devoted to research, but its executives estimate that the entire program might cost $5-10 billion dollars and likely wouldn't deploy its first sail before 2036. As one can well imagine, many engineers and scientists doubt the program would work. One problem involves, what else, money. Some industry analysts have calculated the cost of just the laser system alone at one trillion dollars. Laser propulsion isn't cheap and in the future is unlikely to become much less expensive, as there isn't much of a market for such devices. Secondly, no laser has even come close to generating the energy that these lasers would need to propel the spacecraft. In fact, our most powerful lasers are less than 0.00005% as powerful! Third, the solar sails would have to be perfectly reflexive. The concept is that the laser light will bounce photons off the sails, pushing them forward. If the sail isn't perfectly reflexive, the lasers could vaporize the sails instantly. Moreover, communicating with Earth would prove quite challenging due to the inverse square law: the largest radio telescopes from the Deep Space Network would be hard pressed to capture this information.
So, there are some wrinkles to iron out.
The detractors notwithstanding, Breakthrough Initiatives will persevere in its efforts to perhaps construct the first vessels capable of interstellar travel. Even if this effort succeeds, the sails will not be transporting well manicured humans to distant planetary ports. (Adding people to the payload makes everything exponentially more complicated.) Only the probes will go to the stars. However, in time, perhaps even humans will venture into the final frontier. And, one should never be dissuaded by doubters, just ask President McGovern.
Fifty years ago, the Starship Enterprise soared into our living rooms and instilled in us an ardent desire to explore the many worlds beyond Earth. Truth be told, the impetus to explore has been deeply ingrained in us since our hunter gatherer days. But now, with the aid of astronomy, we have the slightest sense of how much there is to explore in the dark between the stars.
*Mind Spigot: (Every so often I'll share a few thoughts. I'll do so infrequently, as my thoughts are much less interesting than astronomy.) I have to extend credit to Scott, my hiking partner, who is a veritable repository of Star Trek information. During our many meanderings through forests, fields and hills, he has provided me with a thorough education in Star Trek lore, legends and legislation. (For instance, yes, there is indeed a Klingon "Hamlet," and Spock's home world did not have a moon, and Star Trek V was not really William Shatner's fault as there was a writer's strike at the time and I don't like talking about it.) If the Star Trek information contained within this article is accurate, Scott deserves the praise. If it isn't, well, I'll flee into exile out of abject fear. One might be able say, "Well, just round pi down to 3, it makes no difference" to a mathematician and elicit nothing more than an indifferent shrug, but Heaven preserve you if your Star Trek tribute is error riddled.
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FROM THE CATACOMBS OF INFINITE KNOWLEDGE
Snails have four noses
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