What it would take to reach the stars

Feb 3, 2017

By Gabriel Popkin

Anybody who longs to see an alien world up close got an exciting gift last year. In August, researchers reported the discovery of a potentially habitable, Earth-sized planet orbiting the Sun’s closest stellar neighbour — Proxima Centauri, a mere 1.3 parsecs, or 4.22 light years, away.

It’s a tempting — some might say irresistible — destination. Sending a spacecraft to the planet, dubbed Proxima b, would give humans their first view of a world outside the Solar System. “Clearly it would be a huge step forward for humanity if we could reach out to the nearest star system,” says Bruce Betts, director of science and technology for the Planetary Society in Pasadena, California. The data beamed back could reveal whether the alien world offers the right conditions for life — and maybe even whether anything inhabits it.

The idea of reaching Proxima b is not just science fiction. In fact, a few months before the discovery of the exoplanet, a group of business leaders and scientists took the first steps towards visiting the Alpha Centauri star system, thought to be home to Proxima. They announced Breakthrough Starshot, an effort backed by US$100 million from Russian investor Yuri Milner to vastly accelerate research and development of a space probe that could make the trip. When Proxima b was found (G. Anglada-Escudé et al. Nature 536, 437440; 2016), the project gained an even more tantalizing target.

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16 comments on “What it would take to reach the stars

  • @OP – link:-

    What it would take to reach the stars

    A wild plan is taking shape to visit the nearest planet outside our Solar System.
    Here’s how we could get to Proxima b. (see link)

    Experts not involved with the project express a mix of tempered optimism and scepticism.
    “I think there are tremendous challenges” in scaling up laser power and other needed technologies, says Gregory Quarles, chief scientist at the Optical Society in Washington DC. But he adds that with the right level of private and public funding for research into optics and materials, “there will be returns on that investment”.

    Some say that Starshot’s minimalist approach sets the mission apart from previous, less plausible proposals.

    I think it is pure wish-thinking to claim that other proposals are “less plausible”. The technologies for other proposals to use nuclear fusion engines on a large probe are far better established and more credible! – Especially in terms of having a transmitter big enough and powerful enough to send data back to earth!

    “There’s nothing I can see that’s obviously totally impossible,” says Scharf.

    We will have to see haow the long list of challenges and required new technologies work out!

    “They’re not talking about a large ship to another star.”

    In view of the very short transit time through a Centauri star system, the key questions are about the number of instruments and the capability for data transmission, and manoeuvrability of such small probes.

    Others, however, worry that the multiple technological hurdles may prove overwhelming. “I’m cautious about the near-term future of this,” says Betts. “Any one piece seems surmountable, until you realize you have to cram it into a little, tiny, low-mass object.”

    Quite!

    Even if Starshot gets to Proxima b, Andreas Tziolas, president of the space-exploration organization Icarus Interstellar, thinks it is unlikely to provide useful data. “It has an extremely slim to non-existent chance of succeeding in sending an image back from Alpha Centauri,” he says. “You can’t have that small a spacecraft carry enough power to transmit back a signal.”
    Although his organization also studies laser propulsion, he is focusing on a nuclear-fusion-powered mission that could send a much larger spacecraft to Alpha Centauri in a century
    something he says would be powerful enough to beam back useful data and maybe even transport robotic rovers.

    http://icarusinterstellar.org/projects/project-icarus

    The purpose of Project Icarus is four-fold:

    To motivate a new generation of scientists in designing space missions that can explore beyond our solar system.
    To generate greater interest in the real term prospects for interstellar precursor missions that are based on credible science.
    To design a credible interstellar probe that is a concept design for a potential mission in the coming centuries so as to allow a direct technology comparison with [Project] Daedalus and to provide an assessment of the maturity of fusion based space propulsion for future precursor missions.

    Project Icarus was inspired by Project Daedalus, which ran from 1973 to 1978. Project Daedalus, a British Interplanetary Society project, concluded that interstellar travel is feasible.
    Specifically, Daedalus demonstrated that it is possible, by using current or credible extrapolations of existing technology, to launch an interstellar probe that could reach another solar system on timescales of a normal human lifetime.



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  • Icarus Interstellar also have this follow-up project on producing a manned space flight to an exoplanet.

    http://icarusinterstellar.org/projects/project-hyperion

    Project Hyperion

    Many studies of interstellar craft focus on vessels that are unmanned. This is because the task of starship construction is considered sufficiently challenging without the additional complexity of creating an environment where humans could survive for decades or even centuries. Project Hyperion will tackle this specific challenge head on and perform a preliminary study that defines concepts for a crewed interstellar starship.

    Major areas of study include propulsion, environmental control, life support, social studies related to crewed multi-decadal/multi-century missions, habitat studies, communications, psychology of deep spaceflight, mission objectives and ethics of sending humans to the stars.

    I would anticipate that human long term habitations of space, and space based industrial developments within the Solar-System, would be precursors to such flights.



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  • There was an earlier discussion on some aspects of humans preparing for inter planetary and inter stellar travel here:-

    https://www.richarddawkins.net/2016/11/stephen-hawking-just-gave-humanity-a-due-date-for-finding-another-planet/

    I commented @#6, #13, #24, #63, #74, #90, #109, #112, #116, #117, #123, #128, #131, #141, #143, #144, #, #154, #159, #160, #161,

    See also – Phil Rimmer @ #108, #111, #114, #127, #130, #146, #147, #153, #155,



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  • So if we land something on that planet and it’s occupied, will it screw up the Centaurian religions or will their apologists insist it was sent by their god to prove his existence? “Our Father who art on Earth…”



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  • Could you use Proxima Centuri’s Sun to slingshot it back or would it have to get too close. The problems are eminence when you thing about it, the sail would be effected by the solar wind while in the solar system, and the solar wind of Proxima Centuri would also influence it, any tiny fluctuation would blow it off course by an enormous amount. With no ability to steer it’s just shoot and hope for the best. Still, interesting.



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  • Reckless Monkey #5
    Feb 6, 2017 at 1:13 am

    Could you use Proxima Centuri’s Sun to slingshot it back or would it have to get too close.

    The proposed velocity would simply be too high to make a 180° turn using a star’s gravity.
    Any deflection from passing at a safe distance, would be too small.



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  • 7
    maria melo says:

    I cannot describe how amazed I got by this way of traveling (within my imagination it was like traveling in an envelope without engines).
    Well, the red star, sun of this planet will, not end before the sun.
    How to figure out then a way for humans to travel there if it had similar conditions to Earth (“travel in an envelope”).
    Exciting, but a too far future it seems.



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  • Thanks Alan4discussion,

    Sounds like they’d really need some sort of course correction also. All very difficult. Still thinking at the fringes will often give benefits even if not directly for this project.



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  • @maria melo

    How to figure out then a way for humans to travel there if it had similar conditions to Earth (“travel in an envelope”).
    Exciting, but a too far future it seems.

    Humans become exponentially more tricky for a number of reasons. 1) no one wants to really be accelerating for any period of time at greater than 1 G. The advantage of constant acceleration at 1 G is that it would give artificial gravity. And half way there you turn around fire the engines and decelerate at 1G for the remainder of the journey. This little electronic chip would be able to accelerate at much higher rates because it is made of things that are not soft and squishy (although I do not know what rate the solar sail is accelerating the device at – however the longer to accelerate the harder it is going to be to focus lasers on a 4 meter sail, so I’m assuming the mean to do so fairly rapidly (without melting the sail). There were proposals ages ago for nuclear powered space craft one would take hydrogen from space and use it run the fusion engines that fire the craft forward meaning no fuel needs to be carried. However you need something like a kilometer wide funnel to channel the extremely sparse hydrogen. No to mention at the speeds we a talking about any speck of ice of rock would cause enormous damage so you would need something to zap any incoming dust particles etc. The powered required would be enormous. But I’d still like to see us pursue the goal I think it would do us a world of good.

    Just looked it up not 1 km across about 100 km across!

    https://www.youtube.com/watch?v=JQnka2wNa_M

    worth watching this though will blow your mind.



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  • Reckless Monkey #9
    Feb 8, 2017 at 4:51 am

    There were proposals ages ago for nuclear powered space craft one would take hydrogen from space and use it run the fusion engines that fire the craft forward meaning no fuel needs to be carried.

    I don’t think that is feasible. I think deuterium rather than hydrogen would be simpler to use in a fusion engine.

    However you need something like a kilometer wide funnel to channel the extremely sparse hydrogen.

    Rather than trying to scoop hydrogen from space, there are icy minor planetary bodies in the Oort Cloud probably as far out as half way to the Centauri Systems. These could be mined for water ice and deuterium by robot vehicles and the product delivered to the inter-stellar probe or ship by shuttles which dock with it. Thes robot shuttles would not carry passengers, so could be subject to very high G-forces from the very high acceleration needed to chase the starship.

    Not to mention at the speeds we a talking about, any speck of ice of rock would cause enormous damage, so you would need something to zap any incoming dust particles etc.

    While tiny specks would be an impact problem, the bigger pieces would actually be a fuel, oxygen and water source, so mapping them along the route, would be a basic requirement.

    The powered required would be enormous.

    Even early probes would need to be massive!

    http://www.livescience.com/55981-futuristic-spacecraft-for-interstellar-space-travel.html

    But if assembly industries were established in space, sourcing materials mined from asteroids and operating interplanetary craft, (as discussed on the earlier linked discussion @#3), the industrial base for building such structures would be a self financing development prior to these ventures being launched.



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  • @ Alan4Discussion,

    We need to get self assembling machines going as soon as possible then certainly mining asteroids and manufacturing in space would be needed for anything like the scales we’re talking about here. It’s hard to fathom how far away this all looks but there was a great bit in “In the Shadow of the Moon” where one of the Apollo Astronauts was explaining how his father born at the turn of the century around the time of the Wright Brothers could barely believe they’d gone to the Moon but that his son who as 5 at the time thought it was no big deal.



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  • Reckless Monkey #11
    Feb 9, 2017 at 6:24 am

    The power required would be enormous.

    The evolving Icarus probe designs come in several variations using different sizes of probe and different forms of fusion drive.

    The variants are called: Firefly. Ghost, Resolution, Endeavour, Zeus, and UDD.

    Deuterium and Helium 3 (or Tritium) are the suggested fuels. – injected into the engines in pellet or gas form according to the variant of engine design.

    The plan is not for a flyby, but to turn the craft 180 degrees and decelerate before releasing a nominal payload of 100 to 150 tonnes of science probes in the chosen Centauri system.



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  • rjohn19 #4
    Feb 5, 2017 at 4:16 pm

    So if we land something on that planet and it’s occupied,

    Basic bacterial life and archaea are much more likely than complex life on exoplanets.

    There is evidence that this can exist for very long time spans in what to us are very alien environments.

    http://www.bbc.co.uk/news/science-environment-39013829

    Naica’s crystal caves hold long-dormant life

    It is a remarkable discovery in an amazing place.

    Scientists have extracted long-dormant microbes from inside the famous giant crystals of the Naica mountain caves in Mexico – and revived them.

    The organisms were likely encased in the striking shafts of gypsum at least 10,000 years ago, and possibly up to 50,000 years ago.

    It is another demonstration of the ability of life to adapt and cope in the most hostile of environments.

    “Other people have made longer-term claims for the antiquity of organisms that were still alive, but in this case these organisms are all very extraordinary – they are not very closely related to anything in the known genetic databases,” said Dr Penelope Boston.

    The new director of Nasa’s Astrobiology Institute in Moffett Field, California, described her findings here at the annual meeting of the American Association for the Advancement of Science (AAAS).

    First opened by miners looking for silver and other metals a hundred years ago, the deeply buried Naica caves are a key interest to scientists fascinated by extremophiles – microbes that can thrive in seemingly impossible conditions.

    The environment is hot (40-60C), humid and acidic. With no light at depth, any lifeform must chemosynthesise to survive. That is, it must derive the energy needed to sustain itself by processing rock minerals.

    Researchers had identified microbes living in the walls of the caves, but isolating them from inside the metres-long crystals is a surprise.

    These outsized needles of gypsum have grown over millions of years. They are not perfect. In places they have defects – small voids where fluids have collected and become encased.

    Using sterile tools, Dr Boston and colleagues opened these inclusions and sampled their contents.

    Not only did they detect the presence of bacteria and archaea, but they were able also to re-animate these organisms in the lab.

    The concern would be that these organisms might simply be the result of contamination, either introduced by the team or the mining operations. But the Nasa director said that the necessary protocols were followed.

    What gives her confidence in the status of the Mexican caves is the great diversity of life that seems to exist there.

    “Other groups have shown there are lots of viruses in these caves and what that says to me is that these are fully fledged microbial communities that have their viral load just like every other community does. So, that’s another aspect of this that argues against casual contamination,” she told reporters.

    Working for Nasa as an astrobiologist, she is clearly interested in the relevance of such finds to the search for life beyond Earth.

    “The astrobiological link is obvious in that any extremophile system that we’re studying allows us to push the envelope of life further on Earth, and we add it to this atlas of possibilities that we can apply to different planetary settings.”



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  • While it’s a bit far away, this system looks as if it could be brilliant as a source of Earth size planets!

    http://www.bbc.co.uk/news/science-environment-39034050

    Astronomers have detected a record seven Earth-sized planets orbiting a single star.

    The researchers say that all seven could potentially support liquid water on the surface, depending on the other properties of those planets.

    Three of these worlds are within the conventional “habitable” zone where life is considered a possibility.

    The compact system of exoplanets orbits Trappist-1, a low-mass, cool star located 40 light-years away from Earth.

    The planets were detected using Nasa’s Spitzer Space Telescope and several ground-based observatories are described in the journal Nature.

    Lead author Michaël Gillon, from Belgium’s University of Liège, said: “The planets are all close to each other and very close to the star, which is very reminiscent of the moons around Jupiter.”

    So many planets have been discovered in planetary systems beyond our own that it’s easy to become inured to their potential significance. Nasa’s latest tally is an impressive 3,449 and there’s a danger of hype with each new announcement.

    But the excitement around this latest discovery is not only because of its unusual scale or the fact that so many of the planets are Earth-sized. It is also because the star Trappist-1 is conveniently small and dim. This means that telescopes studying the planets are not dazzled as they would be when aiming at far brighter stars.



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  • Alan4discussion #12
    Feb 9, 2017 at 12:51 pm

    The evolving Icarus probe designs come in several variations using different sizes of probe and different forms of fusion drive.

    The variants are called: Firefly. Ghost, Resolution, Endeavour, Zeus, and UDD.

    Deuterium and Helium 3 (or Tritium) are the suggested fuels. – injected into the engines in pellet or gas form according to the variant of engine design.

    On the subject of resourcing fuel for fusion reactors from from orbital sources, this project could provide useful information:-

    http://www.bis-space.com/what-we-do/projects/project-tsiolkovski

    Tsiolkovski mission aims to land a rover in Tsiolkovski crater on the far side of the Moon.
    The rover will land in between the central peak and the northern rim, to sample a combination of mare and highland material. . . . . . A separate sample return probe returns the samples to Earth. . . . . . In addition, the far side maria are rich in helium-3, possible fuel for fusion reactors.




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