In the middle of April
Steven Hawking and
Yuri Milner announced plans to invest roughly $100 million into researching technologies that would allow incredibly small spacecraft to be accelerated by laser light
towards Alpha Centauri, hopefully going fast enough that the probes would reach one of our nearest celestial neighbors in under 20 years from launch day. Many nerds, myself included, got a tad excited, but there are nay-sayers, as well as those who wonder why we should invest in such projects. Why should we spend so much energy creating probes that may or may not A) reach their intended foreign star, B) provide data that probably could be gleaned by telescopes based in this star system, and C) produce any tangible benefits to humans here on earth. In order this article should respond.
A) Will the probe reach the target destination?
Answer: this is the wrong way to phrase the question, these probes will mass less than the spare change in your pocket (assuming you aren't hoarding coins in your pants). The rational behind this kind of mission would be similar to that of how ant colonies work, individual ants may not make it back to the colony, or necessarily provide that much information about the world they explore, but thousands of ants cumulatively do achieve great things. The many hundreds or thousands of probes we send out towards Alpha Centauri will most likely have at a respectable number reach their target trajectory.
B) Will the data be better than that we can get from space based telescopes that we will deploy in this solar system?
Answer: Hard to say, the size of the probes will mean the type of data will be different than that collected by radio or optical telescopes. The kind of data they could collect will be unique, and that should be worth considering. For example the chemical composition of the heliosphere of Alpha Centauri, nano-scale chemical tests could differentiate what molecules are actually found floating around empty space and other stars. If the probes have visual sensors they could take snap shots from angles that are simply not possible from another solar system, even low resolution images at a different angle can provide tremendous clarification on what might be found. Better space buffs will probably have better answers than me.
C) What are the tangible benefits?
Glad you asked, this is where creativity comes in. We are talking about infrastructure designed to launch and accelerate relatively large numbers of super tiny probes into space to 0.2C (which is amazingly fast)
Asteroid Deflection. (hardish)
With the ability to launch these probes, humanity can start being more proactive about how it deflects asteroids. As soon as we detect potentially threatening asteroid orbits, we can bombard asteroids with micro-impactors, the specific impulse for a given impact will be low, the chance of hitting the asteroid will also be relatively low, shooting at moving targets, from a moving object, is hard to do, but it is easier to change a trajectory years out, as opposed to the Armageddon approach (where we wait until the killer is within the moon's orbit). (it is unlikely that the probes would be going at 0.2C (even if the platform could get probes going that fast) as there will be less time to accelerate)
Space Exploration Augmenting. (depends on the target, easy to hard)
Depending on how much targeting control the probes have, one use could be uncovering surfaces on asteroids and moons, similar to how
NASA intentionally shot the LCROSS at the Moon to look for evidence of water. This would make future space mining initiatives far more targeted.
Alternate Propulsion for Larger Spacecraft (really hard)
One of the craziest proposed methods for powering large scale spacecraft capable of brining humans along for the ride is
Project Orion, a vessel powered by the detonation of successive nuclear bombs. For those who don't want to follow the link, imagine a space craft in with two primary features, an upper section, filled with crew quarters, supplies, sensors etc... and a lower section comprised of a giant plate, connected to the upper section by massive hydraulic pistons. While on course towards another body the spaceship would drop a nuclear bomb into position, where the nuke would explode, causing some of the push plates material to evaporate off and provide force. In the current culture we live in, launching a spacecraft into orbit with hundreds, if not thousands of nuclear bombs is just not feasible. But the core idea can be reused, instead of having nuclear bombs push against the plate, hundreds of probes hitting a large spacecraft at 0.01 C or above could conceivably achieve the same goal. A long term space craft could gain velocity from the impact of tens of thousands of accelerated probes. There are some challenges (understatement of the day for me) with this idea. The probes would need to hit the ship with incredible accuracy, too much deviation from the optimal impact angle could cause the ship to spin excessively. The period where the probes could actually be used to augment the acceleration of the ship are also limited. The efficacy of this means of propulsion would require quite a bit of study.
Counter arguments to this suggestion should also be considered. As the smaller spacecraft are primarily being powered by Earth based laser energy, why not directly accelerate the larger craft with the lasers. For short term missions I agree, if you are close enough that the laser can provide sufficient power, for the love of god, use that as an energy source. This strategy is intended for when the larger spacecraft is beyond the point where the laser light is dense enough to provide useful power. It is only at that point where it would make sense to use the impactor suggestion.
If you have any questions comments, feedback, please feel free to write something.
