by Paul Gilster | Feb 15, 2010 | Culture and Society |
When Peter Diamandis talks about the emergence of a ‘let’s just do it’ mentality about spaceflight, anyone interested in getting our species off-planet will listen up. Diamandis, after all, as chief executive of the X Prize Foundation, has been a major force in making commercial space ventures newsworthy. Who can forget the first flight of Scaled Composites’ SpaceShipOne? Diamandis firmly believes we are no longer content to watch government astronauts work in space. It’s time for the commercial sector to take off.
In a new article in the Wall Street Journal (thanks to Erik Anderson for the heads-up), Diamandis lays out our biggest challenge in getting a space-based infrastructure into operation: The cost. Ponder the fact that as the US space shuttle fleet is closed down, American astronauts will need to hitch rides on the Russian Soyuz at a cost of over $50 million per person. That sounds high, and it is, but compare it to shuttle costs of between $750 to $2 billion per flight, depending on the launch schedule. Why so expensive? Oddly enough, the major cost isn’t fuel or payload:
Most people don’t realize that the major cost of a launch is labor. Fuel is less than 2%, while the standing army of people and infrastructure is well over 80%. The annual expense NASA bears for the shuttle is roughly $4 billion, whatever the number of launches.
Image: Astronauts Robert L. Curbeam (USA) and Christer Fuglesang (Sweden) work to attach a new truss segment to the ISS and begin to upgrade the power grid. Will the next fifty years see such operations in the hands of private companies? Credit: STS-116 Shuttle Crew, NASA.
Without the shuttle, we move into a more redundant launch marketplace, one whose competitive nature should ultimately drive down the cost of getting into orbit. Diamandis is co-founder of Space Adventures, which brokers the process of getting private citizens into space. The eight deals it has cut so far have wound up costing roughly $50 million per person. Within five years, that price should be below $20 million, and soon after below $5 million. As prices drop, we can expect a flowering of new space activity:
Within the next several decades, privately financed research outposts will be a common sight in the night sky. The first one-way missions to Mars will be launched. Mining operations will spring up on the moon. More opportunities we have yet to even comprehend will come out of the frontier. One thing is certain: The next 50 years will be the period when we establish ourselves as a space-faring civilization.
That’s a vision that begins to square with the future in space that I used to imagine as a kid instead of the frustrating series of stops and starts we’ve seen in recent decades (though eased by triumphs like Voyager or Cassini). As private capital looks toward space in terms of investment, public/private partnerships pave the way for serious commercialization. S-type asteroids, for example, are composed of iron, magnesium silicates and, as Diamandis points out, various other metals including cobalt and platinum. A half-kilometer S-type asteroid could be worth more than $20 trillion. Diamandis again:
…companies and investors are realizing that everything we hold of value—metals, minerals, energy and real estate—are in near-infinite quantities in space. As space transportation and operations become more affordable, what was once seen as a wasteland will become the next gold rush. Alaska serves as an excellent analogy. Once thought of as “Seward’s Folly” (Secretary of State William Seward was criticized for overpaying the sum of $7.2 million to the Russians for the territory in 1867), Alaska has since become a billion-dollar economy.
It’s always been my contention that we will be forced into building a space-based infrastructure extending to the outer planets because of our need to protect our planet from Earth-crossing asteroids. But Diamandis’ essay reminds us of the key role private industry has played in converting technologies created by the government, from air mail to the Internet, and turning them into robust industries. There is, in other words, abundant opportunity to be found in space much closer to home, with government focusing more on pure science while remaining a major customer of newly energized private operators.
I’ll also buy Diamandis’ timetable of the next fifty years being the period when we either establish ourselves as a space-based civilization or fail in the attempt. Success would inevitably produce the kind of technologies that make exploring the outer fringes of our Solar System, deep into the Kuiper Belt and one day to the Oort Cloud, a workable possibility. We don’t know what propulsion systems might in the next century take us even further, but it’s surely in the process of developing our tools one step at a time — ad astra incrementis — that we’ll one day push our first probes into solar systems other than our own.
by Paul Gilster | Feb 12, 2010 | Astrobiology and SETI |
Panspermia, the idea that life might travel through space to seed other planets and even other star systems, is a fascinating topic for conjecture, and our understanding of the survival of various forms of life in extreme environments only adds to its appeal. But just as SETI has an active counterpart that seeks to send rather than simply receive interstellar messages, so panspermia has its own advocates for a new kind of mission: To seed the stars from Earth. A group called SOLIS (Society for Life in Space) has sprung up around the notion. Its goal:
To propagate our family of organic Life throughout the Milky Way Galaxy and beyond. We propose to seed young planetary systems in star-forming interstellar clouds. We shall design and launch directed panspermia missions carrying the microbial representatives of Life by the year 2050.
So says the SOLIS Web site and so says society coordinator Michael Mautner, who is a research professor in chemistry at Virginia Commonwealth University. Mautner has in the past worked with solar sail expert Gregory Matloff on propulsion systems that would make it possible to seed new solar systems and has written up the idea for the Journal of the British Interplanetary Society. Now he offers a new paper for the Journal of Cosmology that focuses on what he believes to be our obligation to proceed with directed panspermia, ensuring that life does not come to an end.
Panspermia as Obligation
In a short article at Physorg.com, Mautner states his premise:
“We have a moral obligation to plan for the propagation of life, and even the transfer of human life to other solar systems which can be transformed via microbial activity, thereby preparing these worlds to develop and sustain complex life. Securing that future for life can give our human existence a cosmic purpose.”
The idea is that once we have identified planets with conditions suitable for life (and protoplanetary situations where life might one day develop), we should send organisms to seed these worlds as a way of accelerating local processes of evolution. Even the arrival of such a payload onto a comet or asteroid in a distant planetary system could pave the way for its eventual transportation to a habitable planet by local panspermia, in much the same way that material from Mars has occasionally made its way to Earth.
From accretion disks and interstellar clouds to planets identified by Kepler as being in the habitable zone of their stars, the list of targets should be extensive. The propulsion challenge is less of a problem than you might think, for Mautner is in no hurry to get there. Solar sail methods might take hundreds of thousands or even millions of years to deliver their payload, but the idea is long-term survival of life. Capsules containing about 100,000 microorganisms each and weighing 0.1 micrograms would be the delivery mechanism.
Ethics Among the Stars
All of which leads us to the ethical dilemma. How do we choose our targets so as not to disturb already existing life? Mautner considers this in his paper (internal references omitted for brevity):
Can panspermia missions perturb existing extraterrestrial life? At present, there is no conclusive scientific evidence for extraterrestrial life; though admittedly not all scientists share this opinion… Every living cell needs thousands of complex components as DNA, proteins and membranes, and the probability of these components coming together to originate life may be very small even on billions of planets…
If we still detect extraterrestrial life, we can avoid these targets. In any case, we can target new solar systems where life could not have evolved yet. We may seed a few hundred new solar systems, that will secure the future of our family of gene/protein life but will leave all the other hundred billion stars in the galaxy and their possible indigenous life unperturbed.
Yes, we can target locations where life is not likely to have already evolved, but how accurate can our assessments be given the constraints of current observational technology? Moreover, even that approach leads to potential problems. Panspermia assumes movement of life’s building blocks and even life itself through space. Seed a planetary system with life and it could be millions of years before that life moved from an asteroid in the system to a planet in the habitable zone, one that in the interval had developed life forms of its own. We can never be sure we are not displacing local life.
Mautner thinks even this scenario is not a showstopper:
If there is local life there that is fundamentally different, it will not be affected; if it is gene/protein life, it may be enriched and we can induce higher evolution. The new biospheres may prepare the way for human colonization if interstellar human travel becomes possible.
Which Life Survives?
But I’m thinking that sending cyanobacteria to other star systems to consume toxins and pump out oxygen is a dangerous form of meddling because it assumes that forms of life related to our biosphere are the ones that should survive. Ian O’Neill has an amusing but pointed take on this in a recent post:
If our life takes hold of a planet where another life had the opportunity to evolve into an interstellar civilization in a couple of billions of years time, wouldn’t we be in violation of some kind of cosmic anti-monopoly regulation (or at least in violation of the Prime Directive)?
And there’s another thing to ponder: What if “life” is the universal equivalent of some kind of infection. Is life rare because the universe has a very strong immune system? Firing our genetic code far and wide could be considered to be biological pollution.
I’m all for spreading the human influence around the galaxy, but I think this can only be considered if we physically go to these alien worlds, to evaluate these places in person before we start setting up home. Blindly sending life from Earth to habitable worlds and planet-forming accretion disks seems a little reckless, especially as we have no clue about the consequences if we started impregnating unsuspecting planets.
As we await results from Kepler and more from CoRoT, we still have no realistic assessment of the number of terrestrial planets around stars in our galaxy, nor do we have spectroscopic data that can tell us whether or not such worlds bear life. Is the meaning of life wrapped up in self-propagation, as Mautner’s paper suggests? If so, then pushing life from our biosphere outward is simply fulfilling our basic purpose.
But perhaps there is more to life, including the ethical responsibility to let life take its own directions in those niches where it has already taken hold. I’m not persuaded by a panbiotic ethics that doesn’t take into account the huge gaps in our knowledge about how and where life may form.
The paper is Mautner, “Seeding the Universe with Life: Securing Our Cosmological Future,” Journal of Cosmology Vol 5, (January, 2010), pp. 982-994 (available online).
by Paul Gilster | Feb 11, 2010 | Deep Sky Astronomy & Telescopes |
To measure the brightness of a star, astronomers compare it to standard reference stars. You would think measurements of the latter would be highly refined by now, but as this New Scientist story points out, the bright star Vega’s most accurate measurements date back to the 1970s. That puts the focus on a new space telescope, or maybe New Scientist‘s term ‘rocket-borne’ is better here, because the ACCESS experiment will actually not go into orbit, but will make four suborbital flights to make measurements lasting only minutes.
ACCESS (Absolute Color Calibration Experiment for Standard Stars) will look at four common reference stars: Sirius, Vega, and two much fainter objects, HD 37725 and BD+17?4708, with observing time limited to about 400 seconds. That’s not much time, but it’s enough for ACCESS to gauge the brightness of the four reference stars to a precision of one percent and perhaps better, twice the precision of today’s measurements.
Image: Standard Candles are used to calculate astronomical distances.Each of these candles has the same intrinsic luminosity, the only difference is the distance from the observer. Credit: Lawrence Livermore National Laboratory/Universe Adventure.
The accuracy ACCESS will provide is significant because for all the advances we’ve made in instrumentation and calibration, we haven’t been able to transfer those tolerances to our brightness measurements across wavelengths ranging from the visible to the near-infrared. The paper notes an additional problem:
…the absolute normalization of the current astrophysical flux scale is tied to a single star, Vega, a star that is too bright to be observed with today’s premier optical telescopes.”
and goes on to say:
Systematic errors associated with problems such as dark energy now compete with the statistical errors and thus limit our ability to answer fundamental questions in astrophysics.
In other words, ACCESS will play a role in the ongoing investigation into dark energy. Recall that the accelerated expansion of the universe was discovered by studying the brightness of high redshift Type Ia supernovae and comparing them to low-redshift supernovae of the same category. It was found that at a given redshift, the peak brightness of the supernovae was fainter than predicted. The best explanation: These ‘standard candles’ are actually further away than we thought, which means accelerated expansion of the universe, and thus the presence of dark energy, a negative-pressure energy component in the cosmos.
Pushing dark energy studies forward requires highly accurate measurements of brightness, especially since several models have been proposed to explain how dark energy functions, each capable of being tested observationally. The tiniest variations in the expansion rate as the universe grew could be the clue to learning whether we’re dealing with a fundamental new force or evidence of a flaw in our understanding of gravity. Thus ACCESS:
…a sub-orbital program that will enable a fundamental calibration of the spectral energy distribution of bright primary standard stars, as well as stars 10 magnitudes fainter, in physical units through a direct comparison with NIST traceable irradiance (detector) standards. Each star will be observed on two separate rocket flights to verify repeatability to <1%, an essential element in establishing standards with 1% precision.
So ACCESS, whose first flight should be within two years, is all about validating our fundamental standards for astronomical observation. Without it, combining brightness data from multiple telescopes could be misleading. Any talk of new forces should excite our interest as well as our skepticism, but the evidence for continuing expansion is sound and will benefit from further study with the ACCESS results in mind. The paper is Kaiser et al., “ACCESS: Enabling an Improved Flux Scale for Astrophysics,” from Proceedings of the 18th Annual CALCON Technical Conference, 2009 (available online).
by Paul Gilster | Feb 10, 2010 | Interstellar Medium |
We’ve long known that the spaces between the stars are not empty, but are pervaded by a highly dilute mix of gas and dust. Now we’re getting maps that show the presence of large cavities in this interstellar medium, created by supernova events as well as outflowing solar winds from clusters of hot, young stars. The Sun resides in the so-called Local Cavity, a low-density area of neutral gas that is about 80 parsecs in radius. The Local Cavity is, in turn, surrounded by a ‘wall’ of dense, neutral gas, with gaps in the wall — ‘interstellar tunnels’ — that are low-density pathways to surrounding cavities.
We study the interstellar medium by looking at the light produced by stars and using absorption line spectroscopy to see how that light is affected by gases between us and the stars in question. Johannes Hartmann’s classic study of the spectrum of Delta Orionis in 1904 was a huge advance, looking at absorption from the ‘K’ line of calcium and concluding that the gas was not present in the atmosphere of the star but within the matter in space along the line of sight to the star. Interstellar sodium was detected fifteen years later and the study of the interstellar medium went into higher gear, especially in the sightline toward Orion.
This Wikipedia article on the interstellar medium quotes Norwegian explorer and physicist Kristian Birkeland, who described the medium as understood in 1913:
“It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. We have assumed that each stellar system in evolutions throws off electric corpuscles into space. It does not seem unreasonable therefore to think that the greater part of the material masses in the universe is found, not in the solar systems or nebulae, but in ’empty’ space.”
Have a look at the image below, which draws this into perspective. It’s based on new data, gathered primarily at the European Southern Observatory in Chile, that has been folded into previously published results. A French-American team is behind the work, offering up a catalog of absorption measurements toward 1857 stars within 800 parsecs of the Sun. The image shows cold and neutral gas density within a distance of about 300 parsecs.
Image: Map of partially ionized interstellar gas within 300 parsecs around the Sun, as viewed in the Galactic plane. Triangles represent the sight-line positions of the stars used to produce the map. White to dark shading represents the low to high values of the gas density, and orange shading is for areas with no reliable measurement. The Local Cavity is shown as the white area of low density gas that surrounds the Sun at about 80 parsecs. Credit: B. Welsh/R. Lallement/S. Raimond/J.-L. Vergely.
We’re still early in the quest to understand the local interstellar medium, even though many surveys at various wavelengths have been completed. Knowing the chemical and physical characteristics of the medium will help us understand the evolution of stars as they exchange matter with the space around them. From a spaceflight perspective, probing beyond our own Solar System with future technologies will require understanding the spatial distribution and dynamics of the material we’re pushing into, much as early ocean voyagers had to acquire a working knowledge of wind patterns and ocean currents.
The Local Cavity within which our Sun resides is thought to have been created about 15 million years ago by supernova activity, but its history remains highly speculative. The paper is Welsh et al., “New 3D gas density maps of NaI and CaII interstellar absorption within 300 pc,” to be published in Astronomy & Astrophysics 510 (2010), A54 (abstract).
by Paul Gilster | Feb 9, 2010 | Outer Solar System |
New measurements from Cassini, made on a flyby through the plume of Enceladus on March 12, 2008, bolster the case for liquid water in the Saturnian moon. Cassini found negatively charged water ions in the plume, and its plasma spectrometer also traced other kinds of negatively charged ions including hydrocarbons. That adds Enceladus to a fairly select list — the Earth, Titan and the comets — where negatively charged ions are known to exist in the Solar System. They’re found in Earth’s ionosphere, and also in places at the surface where liquid water is in motion, such as waterfalls.
Image: Is there liquid water beneath this surface? Portions of the tiger stripe fractures, or sulci, are visible along the terminator at lower right, surrounded by a circumpolar belt of mountains. The icy moon’s famed jets emanate from at least eight distinct source regions, which lie on or near the tiger stripes. However, in this view, the most prominent feature is Labtayt Sulci, the approximately one-kilometer (0.6 miles) deep northward-trending chasm located just above the center of the mosaic. Credit: NASA/JPL/Space Science Institute
We’ve been examining the case for water, and hence the possibility of life on Enceladus, for some time now. The latest results strengthen that prospect, according to Andrew Coates (University College London), lead author of the Icarus paper on the Cassini data:
“While it’s no surprise that there is water there, these short-lived ions are extra evidence for sub-surface water and where there’s water, carbon and energy, some of the major ingredients for life are present. The surprise for us was to look at the mass of these ions. There were several peaks in the spectrum, and when we analysed them we saw the effect of water molecules clustering together one after the other.”
A BBC story on the findings points out that Cassini has already detected sodium in the plumes of Enceladus, a signature typical of liquid water in contact with deep rock for extended periods of time. And what processes add extra electrons to water molecules? Coates believes the answer may be friction as water comes out of the jets, telling the BBC reporter it would be “like rubbing a balloon and sticking it on the ceiling.” Another possibility: The ambient plasma environment, which further Cassini passes will help us characterize more fully.
Cassini’s plasma spectrometer had previously found large negative hydrocarbon ions in flybys of Titan, with the largest being found at the lowest altitudes that Cassini flew, some 950 kilometers above the surface. Coates’ team suggested in December of 2009 that these large ions could be the source of the dense haze that screens Titan’s surface from view. This news release speculates that the large ions are the organic mix called ‘tholins’ that represent a prebiotic melange of chemicals that can be produced in gases known to be present on Titan.
The paper is Coates et al., “Negative ions in the Enceladus plume,” in press at Icarus (abstract). It’s interesting to see that this is yet another case of a scientific instrument being taken beyond its intended use to return key data. Cassini’s plasma spectrometer was designed to measure the density, flow velocity and temperature of ions and electrons around Saturn. Who among its design team could have imagined it would sample jets around a tiny moon whose evidence of subsurface water excites the interest of astrobiologists?
