by Paul Gilster | Aug 10, 2012 | Culture and Society |
What I have in mind today is a book review, but I’ll start with a bit of news. The word from Houston is that Ad Astra Rocket Co., which has been developing the VASIMR concept from its headquarters not far from Johnson Space Center in Texas, has been making progress with its 200-kw plasma rocket engine prototype. VASIMR (Variable Specific Impulse Magnetoplasma Rocket) offers constant power throttling (CPT), which would allow it to vary its exhaust for thrust and specific impulse while maintaining a constant power level. CPT has now been demonstrated in a June test, as was reported at the recent AIAA Joint Propulsion Conference in Atlanta and in trade publications like Aviation Week, a useful step forward for the program.
VASIMR in Deep Space
What to make of VASIMR’s chances? When assessing something like this, I turn to my reference library, and because I’ve recently been reading Kelvin Long’s Deep Space Propulsion, I wanted to see what he said about VASIMR. Long treats the subject in a chapter on electric propulsion, a form of pushing a rocket in which a fuel is heated electrically, after which its charged particles are accelerated by electric and/or magnetic fields to provide thrust. The VASIMR wrinkle on electric propulsion is to use a fully ionized gas that has been heated hot enough to become a plasma, higher than the norm for most electrical systems.
Long’s explanation refreshed my memory on how all this works:
The engine is unique in that the specific impulse can be varied depending upon the mission requirement. It bridges the gap between high thrust low-specific impulse technology (e.g., like electric engines) and can function in either mode. The company who designs the VASIMR engine talks about possible 600 ton manned missions to Mars powered by a multi-MW nuclear electric generated VASIMR engine, reaching Mars in less than 2 months.
The proof is in the performance, of course, and we’ll see how VASIMR does in actual flight conditions. A 2015 flight prototype is in the works thanks to Ad Astra’s agreement with NASA. But Long’s book bears the subtitle “A Roadmap to Interstellar Flight,” so it’s intriguing to look at long-range developments with this technology. In theory, writes Long, a VASIMR drive could reach an exhaust velocity of up to 500 kilometers per second, corresponding to a specific impulse of 50,000 seconds, which translates into an Alpha Centauri crossing in 2200 years.
Now 2200 years may be progress — after all, Voyager-class speeds take 75,000 years to travel a similar distance — but if we’re talking about practical missions, VASIMR looks to be more valuable in the Solar System, assuming the technology lives up to Ad Astra’s expectations. But Long points something else out. A VASIMR engine could be considered a scaled down fusion development engine. The components that are similar to a fusion engine include the use of electromagnets to create a magnetic nozzle and the storage of low-mass hydrogen isotopes, along with techniques for energizing and ionizing a gas. Long sees VASIMR development as a way forward for understanding how to control plasmas in an engine for deep space.
A Survey of Interstellar Concepts
Insights like that make Deep Space Propulsion an instructive read. I find myself going back to specific sections and finding things I missed. The book has textbook aspects, containing practice exercises after each chapter, but it’s also enlivened by its author’s passion for finding the right tools to make star missions a reality. Long thus works his way through the major options, as we’ve seen in various recent Centauri Dreams articles where I’ve quoted him. Solar sails and their beamed power ‘lightsail’ cousins make their appearance, and so do futuristic concepts like the Bussard ramjet and its numerous variants. Just keeping up with the ramjet idea and how it has mutated over the years is an exercise in itself, but Long also covers antimatter, nuclear pulse (Orion) and exotic ideas like Johndale Solem’s Medusa.
It’s fascinating to work through these chapters and see how various physicists and engineers have tackled the interstellar challenge, spinning out a concept that is seized upon by others, modified, hybridized, and re-purposed as problems emerge and others solve them. Long was the guiding force behind the launch of Project Icarus, which is a re-examination of the British Interplanetary Society’s classic starship design of the 1970s. It makes sense, then, that fusion, which powered Daedalus, should be a major concern and a key element of the book.
Here it’s easy to get lost in the kind of details that, for me, make interstellar theorizing so endlessly fascinating. The BIS engineers knew their spacecraft would be vast to accommodate the propulsion needs of a vehicle designed to make the 5.9 light year crossing to Barnard’s Star, then thought to have planets. Work at Los Alamos and Lawrence Livermore National Laboratory had developed the idea of pulsed micro-explosions of small pellets using laser or electron beams to produce the needed fusion reaction. Long notes the contribution of Friedwardt Winterberg, whose study of electron-driven ignition became the core ideas of the Daedalus engine.
Winterberg is still, thankfully, with us, producing interstellar work that we’ve talked about here on Centauri Dreams, a remarkable link to a classic era of discovery considering that his PhD advisor was Werner Heisenberg. Long goes through Winterberg’s contribution and its adoption by Daedalus, work which continues to inspire the Icarus team as they develop and extend the Daedalus design. What the BIS came up with in the ’70s was gigantic:
The propulsion system for Daedalus used electron beams to detonate 250 ICF [inertial confinement fusion] pellets per second containing a mixture of D/He3 fuel. The fusion products would produce He4 and protons, both of which could be directed for thrust using a magnetic nozzle. The D/He3 pellets would be injected into the chamber by use of magnetic acceleration, enabled by use of a micron-sized 15 Tesla superconducting shell around the pellet. The complete vehicle was to require 3 X 1010 pellets, which if manufactured over 1 year would require a production rate of 1,000 pellets per second.
Not only do you have extraordinary rates of production but you have the problem of finding the helium-3, which the Daedalus team addressed by considering a 20-year mining operation in the atmosphere of Jupiter. We’ll see how the Icarus designers solve the helium-3 issue, but it’s clear that the kind of nuclear starship envisioned by Daedalus would require an infrastructure throughout the Solar System that could reliably maintain large human crews in deep space and move industrial processes and products between the planets at will. There’s that ‘roadmap’ idea Long is talking about, as one developmental step builds upon another to make more advances possible. We can also hope that such advances teach us how best to contain our costs.
Making the Case for Star Missions
Like Gregory Matloff and Eugene Mallove, whose 1989 book The Starflight Handbook reviewed all the interstellar options then at work in the literature, Long’s Deep Space Propulsion offers a mathematical treatment of certain key ideas, especially useful for those coming up to speed on fundamentals like the rocket equation. Long throws in, in addition to the math, a good dose of interstellar advocacy. He’s keen on seeing design studies like Icarus continued around other possible technologies, so that we have constantly developing iterations of everything from nuclear rockets (NERVA) to microwave-beamed sails (Starwisp), a basis upon which future teams will finally build a starship. Along the way, generations of starship engineers learn and master their trade.
Could contests like the Ansari X-Prize be adapted for deep space missions? The book goes into some detail on how this model might work as a way of increasing the technological readiness of different propulsion schemes. But the process is lengthy:
…other authors have estimated the launch of the first interstellar probe will occur by around the year 2200 AD. This includes one author who looked at velocity trends since the 1800s. Factoring the likely uncertainties associated with the assumptions of these sorts of studies, particularly in relation to assuming linear technological progression, it is likely that the first interstellar probe mission will occur sometime between the year 2100 and 2200. To achieve this will require a significant advance in our knowledge of science or an improvement in the next generation propulsion technology. Given the tremendous scientific advances made in the twentieth century, it at least does not seem unreasonable to think that such a technology leap may in fact occur.
Creation of an Institute
Toward that end, Long has recently announced the formation of what he has called ‘the world’s first dedicated Institute for Interstellar Studies,’ whose logo you see here. The Institute is currently building a website and in a recent brochure states an accelerated goal for an interstellar mission:
“Our mission is to conduct activities or research relating to the challenges of achieving robotic and human interstellar light. We will address the scientific, technological, political and social and cultural issues. We will seed high-risk high-gain initiatives, and foster the breakthroughs where they are required. We will work with anyone co-operatively from the global community who desires to invest their time, energy and resources towards catalyzing an interstellar civilization. Our goal is to create the conditions on Earth and in space so that starlight becomes possible by the end of the twenty first century or sooner by helping to create an interplanetary and then an interstellar explorer species. We will seek out evidence of life beyond the Earth, wherever it is to be found. We will achieve this by harnessing knowledge, new technologies, imagination and intellectual value to create innovative design and development concepts, defined and targeted public outreach events as well as cutting edge entrepreneurial and educational programs.”
We’ll track this as it develops — for more information, contact Interstellarinstitute@gmail.com. Meanwhile, those wanting to keep up with the primary interstellar concepts should keep a copy of Deep Space Propulsion at hand. I started this post with a look at VASIMR because the whole range of electric propulsion concepts is intricate and in many ways confusing. Long’s chapter on this goes into the major divisions between the thruster types and untangles the issues around Hall Effect thrusters, MPD thrusters, pulsed plasma and VASIMR in ways I could understand. This is a book that will get plenty of use, and my copy is already filling with penciled-in notes.
by Paul Gilster | Aug 9, 2012 | Asteroid and Comet Deflection |
About a year ago a French couple by the name of Comette returned to their home to find that a meteorite had struck their house while they were away on holiday. It could be said that the Comettes already had a celestial connection — if in name only — but now the heavens impinged upon their lives again, a fact they didn’t realize until their roof began to leak. Living in Draveil, about 12 miles south of Paris, the couple discovered that the space rock had blown right through a thick tile and wedged itself in glass wool insulation. It turns out to be an iron-rich chondrite some 4.57 billion years old.
France, according to this article in The Telegraph, receives the highest number of meteorites per capita in the world, and the Comettes have no intention of parting with this one. The story reminded me of 14-year old Gerrit Blank, who was hit on the hand by a red-hot piece of rock about the size of a pea that went on to create a foot-wide crater in the ground. This was back in 2009 in Essen, Germany, and young Gerrit is doing just fine. I have no idea what the odds of being hit in a meteor strike are, much less of surviving one, but Gerrit now sports a three-inch scar on his hand that will be fodder for countless stories down the line.
Addendum: See the comments below — the Blank story is evidently a fabrication, as I learned after writing this.
Image: A meteor burning up in the atmosphere during the annual Perseid meteor shower, as seen by astronaut Ron Garan aboard the ISS in 2011. Credit: Ron Garan/NASA.
Celestial objects that hit our planet have also been on the mind of students at the University of Leicester, who have gone to work on the 1998 film Armageddon, in which Bruce Willis drills into an Earth-bound asteroid and detonates a nuclear device that splits the object in half. The planet is saved from destruction by this act as the remaining fragments are diverted. What the students were able to demonstrate was that Willis’ method wouldn’t have worked, not unless he had a bomb about a billion times stronger than anything ever detonated on Earth.
The Soviet Union’s ‘Big Ivan,’ says this University of Leicester news release, wouldn’t have stood any chance of splitting an asteroid with the properties described in the film. It turns out that 800 trillion terajoules of energy are needed to split the asteroid and drive its pieces away from our planet, while the total energy output of the Soviet blockbuster was 418,000 terajoules.
So much for Bruce Willis. Moreover, the students found that the asteroid would have had to be split very early in the process, almost immediately after it could have been detected. Now that’s a scenario I can work with — early detection is crucial because you have to allow time to get to the object in question, not to mention deploying whatever threat mitigation tools you bring with you. In the case of Armageddon, the depicted asteroid would surely have struck our planet because we lack the ability to see it soon enough or get to it fast enough.
The papers on this work were published in the University of Leicester Journal of Special Physics Topics and are accessible here. The journal comes out once a year and contains papers written in the final year of the students’ Master of Physics degree, so it serves as training for those planning to become actively involved in scientific publishing. In this case, the idea of taking a popular film and asking whether its science is valid is an excellent corrective. After all, movies like Armageddon reach huge audiences, but all too often contain scientific errors that compromise the story, even if a forgiving audience is ready to overlook them.
But back to smaller celestial debris. Back in 1954, a fragment the size of a grapefruit blasted through the roof of a house in Sylacauga, Alabama, eventually landing — after bouncing off a console radio — upon one Ann Elizabeth Hodges, who was asleep on her living room sofa. Until Gerrit Blank came on the scene, I’m aware of no one else being struck by a meteorite. Remarkably, the Hodges’ rented white-frame house was across the road from the Comet Drive-In Theater, which featured a neon sign showing a comet streaking through the heavens. The meteorite fragment is now found at the Alabama Museum of Natural History in Tuscaloosa.
All of which leads me to note that the Perseid meteors should be turning up late Saturday night and early Sunday morning (August 11-12). Alan MacRobert, a senior editor for Sky & Telescope, says that while the Perseids seem to emanate from the constellation Perseus, they can flash into view almost anywhere as long as the constellation is above the horizon. “So,” says MacRobert, “the best part [of] the sky to watch is wherever is darkest, probably straight up.” And don’t be too concerned about becoming the next Gerrit Blank — the Perseids are pieces of Comet Swift-Tuttle and are more like clumps of dust than lumps of rock and iron.
by Paul Gilster | Aug 8, 2012 | Astrobiology and SETI |
I’m not surprised that Michael Chorost continues to stimulate and enliven the SETI discussion. In his most recent book World Wide Mind (Free Press, 2011), Michael looked at the coming interface between humans and machines that will take us into an enriched world, one where implants both biological and digital will enhance our experience of ourselves and each other. You’ll recall that it was a cochlear implant that restored hearing to this author, and doubtless propelled the thinking that led to this latest book. And it was the issue of hearing and communication that we looked at in an earlier discussion of Chorost’s views on SETI.
That conversation has continued in Michael’s World Wide Mind blog, as he ponders some of the comments his earlier ideas provoked on Centauri Dreams. In particular, how would we ever come to understand an extraterrestrial civilization if it differed fundamentally from us? Chorost thinks the problem is not biological, that no matter how aliens might look, we could study them to understand how they function. What would be far more tricky are questions of technology and culture, and here he brings into play Ken Wilber’s ideas about evolutionary development, notions that can be summarized in the chart immediately below.
Image: Based on Ken Wilber’s ideas of an ‘all-quadrants, all-levels’ model of evolutionary development, this chart shows four axes that trace the development of a society. Credit: Ken Wilber via Michael Chorost.
If you browse through the diagram, you’ll note the likelihood that a society at level 10 on one axis will be at level ten on the other three. Chorost explains:
For example, level 10 in the upper-left quadrant is conceptual thinking. It’s aligned with level 10 in the other quadrants, which are the complex neocortex, the tribe/village, and magical modes of thought. When brains developed complex neocortexes, that was when they were able to sustain the social structures of tribes and villages, along with rituals of propitiation. One could also put it the other way around: tribal structures facilitated the development of the modern neocortex. These are all intimately related and mutually constituting. Each level on each axis is dependent upon, and enables, the others.
All of which seems to make sense, but what we should be pondering are the implications of extending each axis indefinitely. An advanced extraterrestrial species could easily register well beyond 10 on the chart along all four axes, making our need to relate human experience to what we encounter that much more difficult. We may, in fact, lack the neural structures to conceptualize and analogize these advanced levels because an alien culture would have developed modes of thought based on its own experience that are too remote from our more limited grid.
It’s always fascinating to portray encounters with aliens and always a bit aggravating when they show up in Hollywood as clearly human with a few tweaks to make them seem different. But even as we fuss with the producers of such shows for their lack of imagination (or budget), we’re missing the bigger picture. The problem is that we may find our galactic neighbors to be incomprehensible on every level. Here I think, as I often do, of the Strugatsky brothers’ novel Roadside Picnic, in which alien visitors have no apparent interest in humans at all, leaving behind them artifacts that no one can figure out. Their presence tells us that we are not alone, but their departure leaves us with questions of intent — what was their purpose here, and what are the ’empties’ (the book’s term for artifacts) that the aliens have abandoned?
In fact, Roadside Picnic gets across the sense of the inexplicably alien better than almost any novel I have ever read — it should definitely be on the short-list for Centauri Dreams readers. The so-called ‘Visitation’ in the novel involves six different places where the aliens appeared, though they were never actually seen by people living nearby. The ‘zones’ of visitation are filled with unusual phenomena and bizarre items like the ‘pins’ found by the protagonist, who is himself a ‘stalker’ who finds and sells alien oddities like these:
In the electric light the pins looked shot with blue and would on rare occasion burst into pure spectral colors — red, yellow, green. He picked up one pin and, being careful not to prick himself, squeezed it between his finger and thumb. He turned off the light and waited a little, getting used to the dark. But the pin was silent. He put it aside, groped for another one, and also squeezed it between his fingers. Nothing. He squeezed harder, risking a prick, and the pin started talking: weak reddish sparks ran along it and changed all at once to rarer green ones. For a couple of seconds Redrick admired this strange light show, which, as he learned from the Reports, had to mean something, possibly something very significant…
But what? The novel is shot through with ambiguity and mystery. It’s the mystery of Wilber’s diagram extended indefinitely in all four directions, assuming structures of thinking that may be so far beyond our experience as to defeat our every inquiry. In human terms, we can imagine the difficulty in trying to explain sunset colors to a color-blind person. Chorost uses a much better example: The difference between a non-literate society and a literate one. Could science develop in the absence of a written language in which to couch its arguments and record its findings? And just how you would explain these questions and the need to perform these functions with language to someone who had never experienced reading or writing?
It’s possible to see ways around these problems, as Chorost explains:
I’d like to be optimistic. I’d like to think we’d be better off than preliterates puzzling over Wikipedia on an iPad. In his book The Beginning of Infinity, David Deutsch argues that humans crossed a crucial threshold with the scientific method. We now know that everything is explainable in principle, if we make the effort to understand it. Arthur C. Clarke famously said that any sufficiently advanced technology will seem like magic. This may be true, but we will not mistake it for magic. We have a postmodern openness to difference, a future-oriented culture, and well-established methodologies for studying the unknown. Our relative horizons are much larger than our ancient ancestors’ were.
I’m a bit more ambivalent. Yes, we would make every effort to explain an extraterrestrial culture. But I think that even our best methodologies will have trouble untangling motives and intent if confronted with a civilization substantially older than our own. The solution may not be in our hands but theirs (if they have hands). How concerned will they be in establishing a relationship with us? In the Strugatskys’ novel, the aliens have come and gone, leaving behind them little more than enigma. Roadside Picnic gives us a glimpse of what an extraterrestrial encounter may be like unless the culture we meet finds us worth the effort to introduce itself.
by Paul Gilster | Aug 7, 2012 | Missions |
The continued explorations of our two Voyagers have earned these tough spacecraft the right to be considered an interstellar mission, which is how NASA now describes their journeys. Neither will come anywhere near another star for tens of thousands of years, but in this context ‘interstellar’ means putting a payload with data return into true interstellar space. Right now the Voyagers are still within the heliosphere, that great bubble opened out around our system by the Sun’s solar wind, and the signs are multiplying that a transition is soon to occur.
Three measurements are going to mark the boundary crossing, and we’re seeing that two out of the three are in a state of rapid change. This JPL news release points out that on July 28, Voyager 1’s cosmic ray instrument showed a jump of five percent in the level of galactic cosmic rays the craft was encountering. In the second half of that same day, the level of lower-energy particles flowing from inside the Solar System dropped by half. Both measurements had recovered to their former state within three days, but you can see that Voyager 1 is moving through the chop and froth that marks a boundary somewhere up ahead.
Image: The Voyager interstellar mission, pushing up against the edge of the Solar System. Credit: NASA.
The third factor is the direction of the magnetic field, which researchers expect will change direction when true interstellar space is encountered. We should have an early analysis of the latest magnetic field readings some time in the next month. At some point, all three indicators are going to switch over to a more definitive state, but even then we’ll have to see how long the back-and-forth continues in what could be a ragged boundary area.
Noting the gradual increase of high-energy cosmic rays over a period of years and the corresponding drop in lower-energy particles, Voyager project scientist Ed Stone can only say: “The increase and the decrease are sharper than we’ve seen before, but that’s also what we said about the May data. The data are changing in ways that we didn’t expect, but Voyager has always surprised us with new discoveries.” In any case, the flow of lower-energy particles is expected to drop close to zero when the final transition occurs.
As of this morning, Voyager 1, the more distant craft, is 16 hours 46 minutes and 28 seconds light-travel time from Earth, corresponding to 121.479 AU. We’re used to thinking of today’s spacecraft as being far more complex than those of previous decades, but bear in mind that the two Voyagers each contain some 65,000 individual parts, their continued functioning a testament to the skill of the scientists and engineers who designed them. What will eventually silence them is a lack of power as their radioisotope thermoelectric generators lose their punch.
Looking forward, the ultraviolet spectrometer is expected to function until mid-2013, when it will be turned off to save power. But as long as the spacecraft are still operational, the cosmic ray subsystem, the low-energy charge particle instrument, magnetometer, plasma subsystem, plasma wave subsystem and planetary radio astronomy instrument should continue to operate. We’ve got years of data return ahead and can hope for a window between the crossing into interstellar space and the loss of power around 2020 in which to see what surprises Voyager may yet spring about the environment future interstellar craft will have to move through.
by Paul Gilster | Aug 6, 2012 | Outer Solar System |
At $2.5 billion, NASA’s Curiosity rover didn’t cost quite as much as Cassini ($3 billion), but what a relief to Solar System exploration both near and far to have it safely down at Gale Crater. This Reuters story tells me that 79 different pyrotechnic detonations were needed to release ballast weights, open the parachute, separate the heat shield, detach the craft’s back shell and perform the rest of the functions needed to make this hair-raising landing a success. All of this with a 14-minute round-trip radio delay that left mission engineers as no more than bystanders.
Congratulations to the entire Curiosity team on this triumphant event! As we now move into the next several weeks checking the six-wheeled rover and its instruments out for exploration, let’s ponder future targets beyond the Red Planet. For at some point, no matter what we find on Mars, we’re going to want to push on to the outer planets, where intriguing moons like Titan, Europa and Enceladus await. The latter’s stock seems to be rising, as witness this recent article in The Guardian forwarded by Andy Tribick. Although they face major challenges, astrobiological missions to Enceladus offers rich prospects indeed. Two are being studied, and it’s easy to see why.
Increasingly, Enceladus seems to be a natural for astrobiology. Cassini has already shown us that the geysers spewing out of the Saturnian moon’s south pole contain complex organic compounds, and I like what NASA astrobiologist Chris McKay has to say about the place:
“It just about ticks every box you have when it comes to looking for life on another world. It has got liquid water, organic material and a source of heat. It is hard to think of anything more enticing short of receiving a radio signal from aliens on Enceladus telling us to come and get them.”
A subterranean ocean with complex organic chemicals of the sort suggested by the Cassini findings should be an interesting place indeed, especially since it seems to rise close to the surface at the south pole, accounting for the material being vented into space along the ‘tiger stripes,’ long cracks in the crust. All this material is feeding Saturn’s E-ring which, if Enceladus were suddenly to switch off, would likely disappear. McKay calls the venting of water and organics into space ‘an open invitation to go there.’
Image: Geysers at the south pole of Enceladus, as seen by Cassini in a November, 2009 flyby. Credit: NASA.
Answering the invitation would be the Enceladus Sample Return mission, a concept NASA scientists including McKay are putting together that would involve another Saturn orbiter, one that would make periodic flybys of Enceladus to collect plume samples that would eventually be returned to Earth. With Enceladus already pumping sub-surface material into space, a landing there becomes unnecessary. The Enceladus Sample Return mission builds on missions like Stardust, from which we gained expertise in retrieving sample materials from a comet’s tail. The mission is being designed to fit within the parameters of NASA’s Discovery program, which keeps the cost (without launch) at $500 million or below, about a fifth the price tag for Curiosity.
But not everyone agrees that a landing on Enceladus isn’t necessary. The German Aerospace Center (DLR) has been exploring concepts involving landing at the south pole and drilling through the ice. Its Enceladus Explorer would use an ice drill probe that would melt its way down to a depth of 100 to 200 meters to reach a water-bearing crevasse, sampling the liquid found there for microorganisms. A prototype of the device DLR is calling an IceMole has been used at the Morteratsch glacier in Switzerland and is soon to be tested in the Antarctic.
The complicated landing and drilling operation — not to mention the navigation issues faced by the IceMole as it moves through sub-surface ice — make operating the Enceladus Explorer look as risky as Curiosity’s landing on Mars. This excerpt from its project description online explains why the German team is anxious to put instrumentation on the moon’s surface and below:
…water rises to the surface through crevasses and fissures in the ice where it evaporates explosively and freezes instantly. The resulting ice fountains can shoot up to altitudes of several hundred kilometres before the ice particles slowly fall back to the moon’s surface. The microorganisms that could have evolved in the hypothetical ocean of liquid salt water under Enceladus’ icy crust, and have been swept away by the water spouting through the crevasses in the ice, would be extremely unlikely to survive; they would explode at the surface, and all that would remain are the organic compounds whose existence was verified by the Cassini spacecraft.
In other words, forget about microorganisms once they are exposed to the vacuum — all you will see are organic compounds. DLR’s IceMole, in contrast, would examine its samples in situ, sending results back to a base station on the surface that would also serve as the power source for the probe.
Would the chance to study actual living organisms give the edge to DLR’s proposal, or is a flyby the safer and cheaper alternative and the one we’re most likely to see achieved? Ideally we wind up with both missions funded, but no one would be so rash as to predict the mission choices likely from both NASA and ESA in a time of drastically reduced budgets. Let’s just say that Enceladus is staying in the news and that ingenious proposals are emerging for its study.
And it’s interesting to speculate on whether the IceMole technology being examined for DLR’s Enceladus Explorer might be adaptable to other interesting moons like Europa, Callisto or Ganymede. Each presents more problems than Enceladus, but a first-generation IceMole might some day grow into a far more powerful probe that could get a look at Europa’s deep ocean.
