It will take thousands of years for humanity’s fastestspacecraft to reach even the nearest stars.
The BreakthroughInitiatives have been exploring the possibility of reducing this todecades, potentially allowing the scientists who launch the mission to live tosee the results. A new paper, in the Journalof the Optical Society of America B, shows one of the major obstacles forsuch a project can be overcome with existing technology, although the authorsadmit other hurdles remain.
The more mᴀssive an object is, the harder it is toaccelerate it, particularly as you approach the speedof light, representing a major problem for any spacecraft carrying its ownfuel.
Alpha Centauri is the nearest star and planetary system toEarth – it is 4.37 light-years away, but it would take a human about 6,000years to get there with current technology.
“To cover the vast distances between Alpha Centauri andour own Solar System, we must think outside the box and forge a new way forinterstellar space travel,” Dr Chathura Bandutunga ofthe Australian National University said in a statement.Lightweight missions could be given an immensely powerful push and left tovoyage on alone.
The idea of usinglasers to provide this push has been around fordecades but is now being explored more seriously as part of BreakthroughStarsH๏τ. There are many challenges to making this work, but Bandutungaargues the atmosphere needn’t be one of them.
The twinkling of the stars reminds us how much theatmosphere affects incoming light. The same distortions affect laser light sentupwards, potentially preventing lasers from applying the force necessary topush a spacecraft on its way. Some proponents of the idea have suggestedlocating the launch system on the Moon, but the cost would be, well,astronomical.
Bandutunga is the first author of the paper, whichargues the adaptiveoptics used by telescopes to compensate for atmospheric distortion canbe used in reverse. A small satellite-mounted laser pointed down to Earth canbe used to measure atmospheric effects in real-time, allowing the vastly morepowerful lasers located on the ground to adjust, keeping their focus securelyon the space probe.
“Vastly more powerful” is no exaggeration. Previous researchidentified the power requirements for these lasers to transmit to the craft as100GW. The entire United States uses an average of 450 GW of electricity at anyone time.
Bandutunga and co-author Dr PaulSibley are undaunted. “It only needs to operate for 10 minutes at fullpower,” they told IFLScience. “So we imagine a battery or super capacitors thatcan store energy built up over several days and release it suddenly.” The powerwould be delivered from 100 million lasers distributed over an area of a squarekilometer.
The lasers would be positioned invast banks of lasers arrayed in pods of ten. Image Credit BreakthroughsInsтιтute
All this power would be directed at an object no more than10 meters (33 feet) across; by the time the lasers switched off, it wouldbe traveling at about 20 percent of the speed of light. Slowed onlyinsignificantly by the Sun’s gravity and the interstellar medium, the craftcould reach Alpha Centauri in around 22 years, although its transmissions wouldtake another four years to reach us.
Not melting the probe is “Definitely one of the remainingbig challenges,” Bandutunga and Sibley acknowledged to IFLScience. To avoidthis it needs to be a mirror so nearly perfect it would reflect 99.99 percentof the light falling on it, doubling the momentum transfer and reducing heat.
A probe would zip through the Alpha Centauri system in a fewdays, probably never getting very close to a planet. However, the beauty of theidea is that, once the launch system is built, sending additional probesbecomes relatively cheap. A fleet of probes could flood nearby star systems,maximizing the chance one will get a close, if brief, look at any Earthlikeplanets.
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