Centauri Dreams
Imagining and Planning Interstellar Exploration
A Surprise at Lutetia
?Sometimes our spacecraft take us past an asteroid, and other times the asteroid comes to us. Asteroid 2005 YU55 pays Earth a visit soon, closing to a bit less than the distance of the Moon on November 8. The Deep Space Network dish at Goldstone (CA) and the Arecibo facility in Puerto Rico will track the object, with images from Goldstone expected to achieve resolutions as fine as 2 meters per pixel, which should give us a wealth of information about the asteroid’s surface features. About the size of an aircraft carrier, 2005 YU55 was also observed by Arecibo in 2010, when it was found to be roughly spherical in shape with a rotation period of 18 hours.
You’ll also recall asteroid 21 Lutetia, which we covered here when the European Space Agency’s Rosetta probe flew past it in July of 2010. The imagery from that encounter showed a cracked and battered surface, but new analysis now indicates that the asteroid may once have had a hot metallic core. Lutetia may, in other words, be a remnant of an ancient period of planetary formation.
This is interesting stuff because most objects in the main belt between Mars and Jupiter are thought to be relatively light masses of rock and metal that have battered each other for billions of years. Few would have melted to form metallic cores, so the thinking goes, and most would be little more than loosely bound piles of debris. But Holger Sierks (Max-Planck Institute for Solar System Research) and the Rosetta team find that Lutetia is actually quite dense. They based their work on calculations of the asteroid’s volume and mass, drawing on models derived from the Rosetta images and the effect of Lutetia’s gravity on the spacecraft.
Image: A year after the flyby, the analysis shows that Lutetia is a primordial asteroid, with a surface covered in craters, pulverised rocks and landslides. It may also have tried to form an iron core billions of years ago. Credit: ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA.
The Sierks paper on this work puts the matter succinctly:
[Lutetia’s] geologically complex surface, ancient surface age, and high density suggest that Lutetia is most likely a primordial planetesimal. This contrasts with smaller asteroids visited by previous spacecraft, which are probably shattered bodies, fragments of larger parents, or reaccumulated rubble piles.
Look at the surface of Lutetia and you see huge fractures that suggest a porous object that does not square with the density calculations. But Benjamin Weiss (MIT) suggests that melted material beneath the fractured crust — a dense metallic core — would account for the discrepancy. And instead of the idea of asteroids as primordial unmelted objects, we begin to see a boundary line, with the possibility of larger asteroids being partially differentiated, possessing a melted interior overlain by outer layers. Here’s Weiss on the subject:
“The planets don’t retain a record of these early differentiation processes. So this asteroid may be a relic of the first events of melting in a body.”
That would make asteroids like Lutetia unusual but not unique — there may be many objects with unmmelted surfaces but differentiated interiors. The challenge will be to get to an asteroid to return samples that could provide more evidence for this explanation. The smallest asteroids are unlikely to retain a molten interior, but larger bodies in the asteroid belt may prove more interesting than we had realized.
At the time of the 2010 encounter, Lutetia was the largest asteroid ever to have been visited by a spacecraft. Vesta has now eclipsed that record, and the recent findings will make Dawn’s missions at Vesta and Ceres all the more interesting. An asteroid sample return mission — Weiss is part of the NASA team — is slated for a 2016 launch, though not to Lutetia. It’s interesting to note here that earlier work by Weiss on the Allende meteorite showed that samples were strongly magnetized, leading to the theory that the meteorite came from an asteroid with a melted metallic core. All of this may be showing us planetary development in its earliest stages.
The papers are Sierks et al., “Images of Asteroid 21 Lutetia: A Remnant Planetesimal from the Early Solar System,” Science Vol. 334 no. 6055, pp. 487-490 (28 October 2011), abstract available. See also Pätzold et al., “Asteroid 21 Lutetia: Low Mass, High Density,” Science Vol. 334 no. 6055, pp. 491-492 (28 October 2011) — abstract — and Coradini et al., “The Surface Composition and Temperature of Asteroid 21 Lutetia As Observed by Rosetta/VIRTIS,” Science Vol. 334 no. 6055, pp. 492-494 (28 October 2011), abstract available. Weiss’ paper on differentiation is Weiss et al., “Possible evidence for partial differentiation of asteroid Lutetia from Rosetta,” Planetary and Space Science, in press, available online 8 October 2011 (abstract).
New Findings on Eris
Back when I was writing my Centauri Dreams book in 2004, I remember talking to JPL’s James Lesh about various aspects of communicating with distant spacecraft. Lesh had written an interesting paper on how we might communicate with an Alpha Centauri probe, and we went on to discuss laser communications in the context of today’s Deep Space Network. What stuck in my mind about that conversation was how much we can learn when one thing moves in front of another. Lesh pointed out how useful it is to examine a radio signal when a spacecraft moves behind a planet, studying the attenuation of the signal and learning more about the planet itself.
When a celestial object moves in front of a distant star, we also get useful results, as has recently happened in our studies of the dwarf planet Eris. You’ll recall that it was Eris that kicked off a new round of controversy about Pluto, for the early estimates were that the diameter of Eris (then thought to be 3000 kilometers) was actually 25 percent larger than Pluto’s. The possibility of numerous such objects in the Kuiper Belt caused us to reassess the definition of the word ‘planet,’ leading to the creation of ‘dwarf planet’ as the operative term for both Eris and Pluto.
But in November of last year, Eris occulted a distant star, an event monitored at two sites in Chile, including the TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) at La Silla. We learn from this that Eris is close to spherical, assuming there are no large mountains on the object, and that Pluto and Eris are more or less the same size, with the new diameter calculated for Eris coming in at 2326 kilometers (Pluto’s is between 2300 and 2400 kilometers). It’s interesting that Pluto’s diameter is actually harder to measure because even with the help of past occultations, the presence of an atmosphere makes the measurement less precise.
Image: This artist’s impression shows the shadow of the dwarf planet Eris as it was crossing the Earth during the occultation in November of 2010. The regions along the path saw a faint star briefly disappear as its light was blocked by Eris. Studies of where the event was seen, and for how long, have allowed astronomers to measure the size of Eris accurately for the first time. Surprisingly, they find it to be almost exactly the same size as Pluto and learn that it has a very reflective surface. Credit: ESO/L. Calçada.
Eris turns out to be reflective indeed, with an albedo of 0.96 (reflecting some 96 percent of the light that falls on it). This ESO news release notes that this albedo makes the dwarf planet brighter than fresh snow on Earth, flagging it as one of the most reflective objects in the Solar System, in company with Saturn’s moon Enceladus. Moreover, studies of Eris’ moon Dysnomia help us arrive at a mass estimate for Eris, which turns out to be 27 percent heavier than Pluto, with a density estimated at 2.52 grams per cubic centimeter. Emmanuel Jehin, one of the researchers involved in the occultation study, says this about the finding:
“This density means that Eris is probably a large rocky body covered in a relatively thin mantle of ice. This layer of ice could result from the dwarf planet’s nitrogen or methane atmosphere condensing as frost onto its surface as it moves away from the Sun in its elongated orbit and into an increasingly cold environment.”
Estimates suggest a surface temperature of -238 Celsius on the day side of Eris, but when the object moves back toward perihelion in its orbit (37.8 AU), the ice Jehin is talking about may well turn back into gas. Eris is currently at 96.6 AU, near aphelion. Telescopes at 26 different locations around the globe were used to observe the occultation, but the dwarf planet’s shadow was only detected at the two sites in Chile, where a sudden drop in brightness was apparent. But even with small telescopes, the value of one celestial object moving in front of another is again demonstrated, helping us learn more about a dwarf planet on the edge of the Solar System.
The paper is Sicardy et al., “A Pluto-like radius and a high albedo for the dwarf planet Eris from an occultation,” Nature 478, 493-496 (27 October 2011). Abstract available.
JWST: The Starshade Option
Imaging an Earth-like planet in the habitable zone may happen some time in the next decade if the James Webb Space Telescope can make its way through its budgetary hurdles and achieve a 2018 liftoff. But the word ‘imaging’ is a bit deceptive when you consider that we won’t be getting anything remotely like the view of a planet in our own Solar System through Webb’s instruments. No small disc with discernible features, in other words, but a single dot useful not because of what we can pick out visually, but because we can use its light to take a spectrum. And if we’re really lucky, we’ll find a dot that’s blue and a spectrum that shows the signature of a living world.
The JWST works at infrared wavelengths (covering a range from 0.6 to 28 micrometers), which is why shielding it from heat is so important, and why the design is marked by a large sunshield. These wavelengths should allow the instrument to study stars and galaxies from the early universe, but the addition of a starshade to the mission concept would enhance the exoplanet part of the conversation. In a recent Astrobiology Magazine article, Leslie Mullen talked to Matt Mountain and John Grunsfeld (Space Telescope Science Institute) about what a starshade might do (thanks to Erik Anderson for the tip). Think of a disc tens of meters wide with petal-like extensions placed between telescope and star. Mountain likened the starshade to putting your thumb in front of the Sun to create shadow:
[The starshade is] very carefully shaped, so you don’t get the sort of flaring that you normally get when you use a perfect sphere, where you get all these rings and refractions. These petals are designed to create a very smooth, very deep shadow. You basically slide in and out of the shadow, and then you can actually see the planet next to the star. The star is in the shadow, and the planet peeks around the shadow.
Image: A starshade would obscure the light of a star to allow its planets to become visible. Credit: Webster Cash/University of Colorado, Boulder.
The starshade would be placed 160,000 kilometers away from the JWST, which will orbit at the L2 Lagrangian point. And as Grunsfeld points out, that single dot yields other information:
…if you had enough time, and there were seasons, with ice covering and then going away, you could study it and be able to tell the difference between winter and summer on the planet, or vegetation, in principle. Just from unresolved single pixels, because of the color changes.
Given our inability to get a finalized Terrestrial Planet Finder design into the mix, the JWST thus becomes a major exoplanet asset, though a mission of daunting complexity, and one whose orbit would make any necessary on-site repair problematic, to say the least. Unlike Kepler, this is an instrument that can sample stars that are relatively near to the Earth. Most of the 150,000 stars in the Kepler field are further away, chosen because the goal of Kepler is to study a large number so as to achieve a statistical analysis of the incidence of the various kinds of planets around them.
Image: What a starshade might see, based on studies for a starshade concept called New Worlds Observer, one we’ve discussed many times on Centauri Dreams. The image shows an Earth-like planet at a distance of 30 light years. The white ring is dust in the stellar system, reflecting starlight under an angle of 30°. The central black disk is the shadow cast by the starshade. The Earth-like planet is the object with the familiar blue hue. Credit: Phil Oakley, Webster Cash (University of Colorado, Boulder).
Adding a starshade to the JWST mission profile adds to both cost and complexity, but the starshade would extend the telescope’s ability to see exoplanets. On its own, JWST can study a transiting world, but Mountain figures such transits might show up in no more than 5 to 7 percent of stars. The ability to take a planetary spectrum independent of the planet’s orientation around the star is what the starshade offers. We now wait to see whether JWST itself has a future. Its ballooning costs have threatened the project in Congress, but NASA administrator Charlie Bolden sees the telescope as one of the agency’s top priorities. With $3.5 billion already spent and ¾ of the construction and testing complete, Centauri Dreams thinks this mission will fly, but not without the kind of budgetary near-miss that is the nemesis of complex science everywhere. The loss of the Space Interferometry Mission will always be a reminder of what can still happen.
The Next NASA Sail
Back in August I mentioned NASA’s solar sail plans beyond NanoSail-D in the context of a larger survey of sail designs and experimentation. It’s great to see multiple sail projects in motion, and before I return to NASA I should mention not only the Planetary Society’s ongoing sail effort but the CubeSat sail being built by a consortium from the University of Surrey and aerospace firm Astrium, an aerospace subsidiary of the European Aeronautic Defence and Space Company (EADS). Then there’s the German space agency DLR and its Gossamer sails, experimental designs being worked on with the European Space Agency. Surely energized by the success of the Japanese IKAROS sail, work on this fledgeling space technology is beginning to ramp up.
NASA’s next step in sail design builds upon the earlier work the agency performed with aerospace contractor L’Garde Inc., of Tustin, California, which deployed and tested a 20m X 20m sail at the agency’s Plumbrook facility in Ohio. The plan is to build a solar sail demonstration mission that will create a sail quadruple the size of the Plumbrook sail and conduct operations in space to demonstrate attitude control as well as passive stability and trim adjustment using beam-tip vanes. The demonstrator mission will also allow the craft to execute basic navigation operations.
Image: A four-quadrant solar sail system sits fully deployed in a 100-foot-diameter vacuum chamber at NASA’s Glenn Research Center Plum Brook Station in Sandusky, Ohio. NASA’s solar sail propulsion team at the Marshall Space Flight Center in Huntsville, Ala., and its industry partner, L’Garde, Inc., of Tustin, Calif., successfully deployed the solar sail system during testing at the Plum Brook facility in early July 2004. The tests included temperatures as cold as minus 112 degrees Fahrenheit to simulate conditions of open space. Credit: NASA/L’Garde, Inc.
Technology demonstrator missions like this one provide near-term spacecraft that can show the feasibility of new technologies, and that means flight hardware tested in space. The plan is for the sail mission to piggyback with other payloads aboard a commercially available launch vehicle, with launch scheduled for 2015 or 2016, and a one to two year period of spacecraft operations and analysis. NASA talks about future solar sail capabilities in the realm of satellite deorbiting (essentially using the sail as part of a satellite payload for this purpose) and station-keeping, allowing ‘pole-sitter’ sails, for example, for geosynchronous high-latitude operations.
The final purpose, as noted in this NASA news release, is to develop sails for deep space propulsion, but we’ll need to build up a sail capability much closer to home before we can think of committing serious payloads for these purposes. We’ll doubtless see attempts at something like GeoStorm, which would place solar storm warning satellites at positions between the Earth and the Sun to increase our warning time for solar flares. The demonstrator sail is a precursor to all these applications, and NASA’s work with L’Garde and the National Oceanic and Atmospheric Administration should be seen as part of firming up sail techniques as we aim for bigger missions.
Another part of that process would be to move into space-based experimentation on microwave beaming. Back when the Planetary Society was planning for the ill-fated Cosmos 1 sail (lost evidently without achieving orbit in a booster accident), the plans included an attempt to measure the effect of microwaves on the sail using the Goldstone dish. It would be heartening to see this kind of thinking continued in the next round of missions. My own take is that beamed sails offer huge advantages for deep space, including not just the fact that the spacecraft does not carry fuel onboard but that the physics of microwave beaming to a sail are comparatively well understood. More on beamed sail concepts soon as we look at some of Jim Benford’s thoughts on the idea.
Water Found in Planet-Forming Disc
An orange dwarf star a bit smaller than our Sun is giving us valuable clues about how water-covered planets like Earth may evolve. TW Hydrae is 176 light years away, so young (5 to 10 million years) that it is still in the early stages of forming a planetary system. Working with data from ESA’s Herschel space observatory, astronomers have found cold water vapor in the disc of dust and gas that surrounds the star. It’s a significant find, because while we’ve found warmer water vapor in proto-planetary discs closer to their star, we now see evidence for much larger amounts of water in the outer disc, where the material for icy comets is found. Current theory holds that water will be far scarcer in the inner solar nebula around a coalescing system, meaning extensive oceans would have to be delivered by impacting objects from the outer regions.
The Herschel data show the distinct signature of water vapor, probably produced when ultraviolet radiation from the central star warms ice-coated dust grains, causing some water molecules to break free of the ice to create the thin layer of gas found by Herschel’s Heterodyne Instrument for the Far-Infrared (HIFI). TW Hydrae’s disc extends to 196 AU, and the assumption is that as matter within the disc grows into planets, much of the outer dust and ice will coalesce to become comets. Cometary bombardment in the emerging solar system could then produce oceans on the inner worlds there, a process that this work indicates may be common. Says Caltech’s Geoff Blake, one of the team of researchers investigating TW Hydrae: “These results beautifully confirm the notion that the critical reservoir of ice in forming planetary systems lies well outside the formation zone of Earthlike planets.”
Image: This image shows an artist’s impression of the icy protoplanetary disc around the young star TW Hydrae (upper panel) and the spectrum of the disc as obtained using the HIFI spectrometer on ESA’s Herschel Space Observatory (lower panel). The graph in the lower panel shows the spectral signature of water vapour in the disc. Water molecules come in two “spin” forms, called ortho and para, in which the two spins of the hydrogen nuclei have different orientations. By comparing the relative amounts of ortho and para water, astronomers can determine the temperatures under which the water formed. Lower ratios indicate cooler temperatures, though in practice the analysis is much more complicated. The ratio of ortho to para water observed in TW Hydrae’s protoplanetary disc is low enough to point to the presence of cold water vapour. Credit: ESA/NASA/JPL-Caltech/M. Hogerheijde (Leiden Observatory).
Michiel Hogerheijde ( Leiden University) relates the process to our own Solar System:
“The detection of water sticking to dust grains throughout the disc would be similar to events in our own Solar System’s evolution, where over millions of years, similar dust grains then coalesced to form comets. These comets we believe became a contributing source of water for the planets.”
Simulations that folded the new Herschel data in with Spitzer observations as well as ground-based studies allowed the team to calculate the total amount of water in the TW Hydrae disc, an amount equal to several thousand Earth oceans. Studying such raw materials of planetary formation should help us understand how systems evolve, which is why upcoming Herschel studies of three more young stars with similar discs should be so interesting. The expectation is that more water vapor should turn up, supplying additional evidence for the kind of icy reservoir from which water-covered worlds can draw as infant solar systems emerge.
The paper is Hogerheijde et al., “Detection of the Water Reservoir in a Forming Planetary System,” Science Vol. 334 no. 6054, pp. 338-340 (21 October 2011). Abstract available.
Related: Earth’s Oceans: A Cometary Source After All?
Project Icarus: Extreme Aerospace Engineering
by K.F.Long, co-founder Project Icarus
Kelvin Long is well known to Centauri Dreams readers. The physicist and aerospace engineer is, in addition to being one of the most energetic voices in the service of interstellar propulsion studies, the co-founder of Project Icarus, the successor to the 1970s-era Project Daedalus starship design study. Here Kelvin looks at where the ongoing Icarus effort stands in terms of fusion, placing that propulsion option in the context of the broader questions raised by pushing a payload to the stars.
Back in December 2009 I wrote an article titled Project Icarus and the Motivation Behind Fusion Propulsion. This was an attempt to justify the initial design choice of the team as part of the engineering requirements for the study that is Project Icarus.
Despite this article and other discussions we have had, we have recently learned something from our experience at the 100 Year Starship Study Symposium: People still don’t understand the Daedalus connection and fusion choice behind Project Icarus. I shall attempt to explain it in order that the Centauri Dreams readers can follow the process that led to this apparently controversial decision.
Firstly, let us address what makes Project Icarus so unique – its Daedalus heritage. Why was the project chosen to be this particular way? There are four reasons for having made this decision:
- Because Project Daedalus was the only full systems integrated study ever performed in the interstellar community and no-one had gone back and revisited an old design in this way.
- To provide for a solid foundation to start with by putting the new design team in contact with the original Daedalus team and others in the community.
- To provide for a reliable technology maturity comparison given the nearly four decades of scientific progress, something else not attempted before.
- To give the team images to feed the media whilst we were developing our design and allow us to inspire the public, thereby building the momentum behind the project.
On the evidence for how the team has grown to date and the opportunities that have come our way, it is the view of this author that these decisions have been validated. We started from a very strong foundation, initially supported by the British Interplanetary Society and the Tau Zero Foundation. We made all of the right connections and gradually embedded ourselves within the interstellar community. In particular, we have gone out of our way to meet many of the giants of the field such as Geoffrey Landis, George Miley, Marc Millis, Terry Kammash, Eric Davis to name a few, and convince them that what we were doing had intellectual value. From discussions it appears they are largely in agreement.
Image: Kelvin Long (left) and Alan Bond, one of the original Daedalus designers, at the headquarters of the British Interplanetary Society. Credit: K. Long.
Training the Starship Designers
Now let’s look at another bit of thinking behind the project, the interstellar community itself. I have already mentioned some names above. Some of the other greats in the subject have sadly left this world having made an astonishing contribution to the literature of interstellar flight. This includes inspiring people like Carl Sagan, Robert Forward and Robert Bussard, to name just a few. There are many other greats still working away. Greg Matloff is one of them, working as a consultant to Project Icarus by mentoring the design team and passing on his wisdom and experience. He still publishes papers and lectures at the same pace as the rest of us. Similarly, many of the original Project Daedalus team are still around, including Alan Bond, Anthony Martin and Bob Parkinson. But they are either in retirement or busy with other projects. Alan Bond of course is the Managing Director of Reaction Engines Ltd and this keeps him busy enough. Despite this, he still manages to find time to keep an eye on developments in the field, even attending the BIS World Ship symposium back in September this year.
But to cut to the chase, how many young people are working on interstellar research? Where is the next generation working on interstellar research problems? Who will pick up the baton and stand on the shoulders of our interstellar research giants? Enter Project Icarus.
Project Icarus is at heart a training exercise. It is an exercise in designer capability at the extreme end of aerospace engineering. The choice of fusion propulsion is not relevant to this ‘educational program’. All of the people involved in Project Icarus are essentially in interstellar school and hope sometime, perhaps around the year 2014 – 2015, to graduate first in their class.
We all have our pet favourites for how to get to the stars. My personal favourite happens to be internal and external nuclear pulse propulsion although I am also very interested in antimatter concepts. Additionally, other than Project Icarus, I am also involved with two solar sail projects. Others within the Icarus team also have their favoured methods for reaching the stars, including microwave beaming concepts to faster-than-light drives. One of these methods or a combination of these methods, a propulsion hybrid, may someday be the actual method by which we attain the journey and reach those far off destinations. But guess what, it doesn’t matter what the option is if there isn’t anyone around capable of doing the work and advancing that option technically. So Project Icarus aims to train the design team so that when they complete the project they are ‘capable’ of doing the necessary calculations to assess all of these options and thereby advance them all incrementally.
Fusion and Future Design
The Project Terms of Reference (ToR) document stipulate that the propulsion system must be mainly fusion based propulsion, to maintain continuity with Project Daedalus and allow a claimed ‘redesign’, which would otherwise be difficult to justify. From internal discussions within the team, we have interpreted this to mean that energy generation through fusion reactions should be responsible for around ~80-90% of the thrust generation during the boost phase. This work is defined under the Primary Propulsion module, led by Richard Obousy, the former Project Leader. This leaves around ~10-20% of the thrust generation during the boost phase to be augmented with alternative propulsion technologies. This work is defined under the Secondary Propulsion module, led by Andreas Tziolas, the current Project Leader. Project Icarus officially started in September 2009. Since that time members of the team have done various calculations and trade studies pertaining to nuclear fusion, antimatter, nuclear thermal propulsion, plasma drives, solar sails, magSails, Medusa sails, microwave beams, Orion-type drives and even Vacuum Energy concepts. A ToR needed to be defined at the beginning to constrain the design problem, otherwise a five year study would turn into a ten year study.
When Project Icarus is finally over, it is my personal aspiration that members of the design team will go off and seed other design projects across the propulsion spectrum, because they will have the knowledge and the skills to do so. Essentially, Project Icarus is injecting energy into the subject of interstellar studies. It is hoped that this energy will act as a catalyst and spread across the entire subject, through inspiration, hard work, enthusiasm and compelling reasons for trying.
Image: Icarus being assembled in Earth orbit. Note the SKYLON spaceplane delivering components. Credit: Adrian Mann.
What you are witnessing in Project Icarus ladies and gentlemen is a classroom in action, played out on the World Wide Web. It is a pilot program for a Starflight Academy. If you want to train a bunch of people up quickly, the best way to do that is to throw them in the deep end with an engineering problem and say “go solve that”. This is precisely what the Project Icarus Study Group is attempting to do, where the specific exam problem is defined by our ToR, merely a mechanism for facilitating this goal. Perhaps someday a real Starflight Academy will exist, and teams will similarly be solving problems relating to many interstellar propulsion concepts. And it’s not just all about propulsion of course. A spacecraft design needs structure, materials, communications, reliability and a variety of other assessments to prove that it is a credible concept. We’re working on all those issues too and in the future will be taking more active steps to communicate some of that research to you the readers – something else we realized from the Orlando 100 Year Starship Study Symposium. People want to know some of our research findings and we need to start talking.
On a final note, I ask the readers not to see Project Icarus as an initiative that necessarily advocates fusion propulsion as the best way forward in reaching the stars. It happens to be the view of some members of the team, but others take a different view. Fusion propulsion and the Daedalus design, as studied within Project Icarus, is merely a vehicle upon which to train the eager young space cadets for the future. So that when we really do need that starship in a hurry, whatever the propulsion option of choice, we have a team ready and waiting to go and design it. Meanwhile, we will continue to wave our fists at the Sun and dare to “fly closer to another Star”, building on our forefathers who did that seminal Project Daedalus study in the 1970s. Like a son to a father, we hope to make them proud of our efforts and along the way find a way to build a better machine.
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