Daily Archives: February 6, 2017

Most people would probably say yes, its quite possible there will be humans residing on the moon within the next ten years, and it will be relatively inexpensive too. Much of this is down to 3D printing, robots, and SpaceX. Whatever the reason, its a cool concept and one that deserves exploring. Out of a workshop help in 2014, came nine papers that have been prepared specifically for the task of setting up an alternative environment on the moon. Although all nine papers differ in detail, essentially they are all working towards that same goal.

But, its not the first time people have talked about setting up a base on the moon, and so far nothing, so whats changed? Chris McKay, NASA astrobiologist, says, The reason all the previous plans for going back to the moon have failed is that theyre just way too expensive. The space program is living in a delusion of unlimited budgets, which traces back to Apollo. This was a project that cost $150 billion by todays standards.Today, however, estimates from the papers suggest that we could have a base in place on the moon by 2022 and for less than $10 billion.

As it stands, NASA has no intentions of returning to the moon and instead is looking at Mars as the next place of colonization. But people such as McKay and others feel that we need to conquer the moon first before trying to take on the likes of Mars. This would allow astronauts the chance to test new equipment and habitats just a few days away on the moon rather than nine months away on Mars. My interest is not the moon. To me, the moon is as dull as a ball of concrete. But were not going to have a research base on Mars until we can learn how to do it on the moon first. The moon provides a blueprint to Mars.

Others besides NASA that are also looking to get a base set up on the moon include China, Russia, and the European Space Agency. So even if NASA didnt want to fund the mission alone, it would soon be able to partner with another source. Private investors also want to go back to the moon, even if just as a stepping stone to Mars. But, how do we even go about building a lunar base there? Well, that will vary depending on who you ask, but many proposals will include some form of robotic exploration to find the perfect site for the living. Next, lunar excavation machines would set to work leveling the area while more robots would start to set up a solar power network.

It would take a while for the majority of people to start living on the moon, and at first, only a small crew would stay for a few days at a time. The missions would be increased each time until eventually there was a permanent base established, suitable for humans to reside on. It really shouldnt be that difficult either, as we already know how to survive on the moon. Now its a case of using the technology around us to drive down the cost of a moon base. Using VR technology could help with the planning of the mission and 3D printing could be used to replace any small components that happen to break on the spacecraft.

Some of the proposals were relying on technologies that arent even in existence yet, but not completely out of this world. One idea involved SpaceXs Falcon 9 rocket transporting small payloads or the Falcon Heavy taking large payloads to the moon, while another was to allow rockets to refuel in orbit. The moon lodgings are likely to be designed and manufactured by Bigelow Aerospace who have come up with a dwelling that is flexible and can be folded up to fit inside the cargo bay of a rocket, then simply expand on the lunar surface, similar to that of a pop-up tent. Test versions of the moon lodgings will be trialed at the International Space Station later this year.

The whole project doesnt come cheap, and its estimated that the cost of building a lunar base on the moon will be around $10 billion, with annual upkeep costs of around $2 billion per year. But, NASA can afford it especially if they team up with some private investors. One study last year showed that the project could even pay for itself after one year if large water deposits are found on the moon. And, whats more, is all of this could be up and running in less than ten years. How exciting!

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Will We Really Be Living on the Moon Within the Next Decade? - TrendinTech

"The Space Between Us" is apparently a large divide when it comes to describing this silly, romantic, mixed-up movie.

It's an interplanetary adventure as a science-fiction flick with a race against time.

It's a teen romance (involving a girl named Tulsa!) formed around a fish-out-of-water story.

It's a morality play, and it's a redemption story.

It's a mess, more than anything, that goes from a convoluted, boring first hour to a second half that is such a heart-on-its-sleeve love story, aimed so squarely at tween girls, that your 12-year-old daughter may walk out of the theater swooning.

That may be the one group of people whose space between their ears will really appreciate "The Space Between Us."

Initially set in the very near future, NASA sends a shuttle of astronauts to prep Mars for colonization, but there's a problem: One of them is pregnant. The baby is born on Mars, and the mother dies in childbirth.

That makes Gardner Elliott the first human not born on Earth, and that makes him different.

No. 1: A full gestation in zero-gravity atmosphere means his organs are different than our own, endangering his ever coming home.

No. 2: Sentencing him to live on Mars is a bit of a public-relations nightmare, so his existence is kept a secret from the public.

I know what some may be thinking, but no: The moon landing was not faked.

This whole snafu leaves Gary Oldman, as the architect of this Mars mission, fretting and yelling at people about this massive cover-up, and it leaves a motherless boy stuck with astronauts inside a small space station for the first 16 years of his life.

Asa Butterfield ("Miss Peregrine's Home for Peculiar Children") already proved his sci-fi teen mettle in "Ender's Game," and now as Gardner he gets an upgrade to romantic lead.

But it takes forever to get him there in the hands of director Peter Chelsom ("Serendipity," "Hannah Montana: The Movie").

Between Oldman's rants down on Earth, Mars mother-figure Carla Gugino's sentimental concerns for the boy and Gardner's repeated questions What's Earth like? What's your favorite thing about Earth? Will I know how to act on Earth? that the only thing that kept me from snoring was thinking out loud: When are you going to get this boy on Earth?

The movie never really takes off until we get Gardner in front of Tulsa, the teen girl in Colorado he's been secretly future-texting from Mars, where the wi-fi is red planet-hot.

Tulsa is played by Britt Robertson, who was the one good thing about "Tomorrowland" and who, at 26, is so pretty that she can make us believe she's still in high school.

It turns out that she was abandoned at age 4 in Tulsa, and the orphan girl adopted the city as her nickname.

So we can see that bond start to form: Both Gardner and Tulsa grew up without parents, forced to live with strangers who didn't always tell them the truth.

Butterfield brings an awkward, goofy, somewhat cute manner to his discovery of Earth things both large and small, from crawly bugs to homeless people to Robertson's lips.

Robertson, playing the street-smart girl who can steal a car as easily as she takes off in a crop-dusting plane, brings a blushing sweetness to her tough chick, whose defenses weaken in the presence of a true innocent.

After a sloooow-developing period of great length, it's remarkable that the final act is as moving in a sappy kind of way as it is. Admittedly, my 12-year-old daughter may have coaxed that feeling along.

She and her friends are the audience for "The Space Between Us," and those accompanying them will just have to grin and bear it.

Michael Smith

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michael.smith@tulsaworld.com

Twitter: @michaelsmithTW

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Movie review: "The Space Between Us" is aimed squarely at teens - Tulsa World

In Syfys The Expanse, Mars and Earth are two superpowers racing to gain the technological upper hand, while those who live in the Asteroid Belt mine resources for the more privileged planets and become more and more prone to radicalization.

Sound familiar?

As we enter the miasmatic era of a Donald Trump presidency, it is impossible not to view televisionany pop culture, for that matterthrough the lens of politics. Dystopian science fiction in particular warrants comparisons to present-day society, or at least points to where it might be headed. But finding allegories in fiction isnt necessarily a bad thing, and former President Barack Obamahimself has said that fiction can be a reminder of the truths under the surface of what we argue about everyday.

The Expanse does just that, only its the 23rd century, and humanity has successfully colonized the planets in the solar system. No, there is no demagogue with tiny hands running a planet in this story, but there are other obvious similarities you can draw: Marginalized communities are pitted against the wealthy and elite, limited natural resources cause war and strife, and nations are constantly poised on the brink of war.

But The Expanse doesnt merely copy and paste current global affairs into its story. Instead, the show uses a nuanced, character-driven narrative to combat a Trumpian view of the worldone that eschews complexity by boiling down politics to simply good versus evil. Authoritarianism perpetuates the idea that nuance does not exist, only the impetus to quell opposition, and as Ruth Ben-Ghiat in The Atlantic points out, this leaves society open to the possibility of violence without consequence. The Expanse, on the other hand, manages to paint a portrait of a divided universe without vilifying one group and raising the other to god-like status, a kind of storytelling that will be essential in the coming days.

The series achieves this feat by making us question who the real heroes in its story are. Is it Chrisjen Avasarala (Shohreh Aghdashloo), operative of the United Nations, which controls Earth and the moon colony? Avasarala wants to protect the citizens of her planet and uphold Earths ideals of welfare and social reform, but she does so in a way that blatantly ignores civil liberties. We see this when she tortures a Belter for information, and when she repeatedly betrays friends and allies in order to achieve her goals. She is ruthless and cold, determined and vicious. Yet we also have to wrestle with the fact that she lost her son to terrorists, and her determination to stifle insurrection comes from her loss and her fear.

What about Joe Miller (Thomas Jane), the hardboiled detective who lives in the Asteroid Belt? On the surface, it looks like hes fighting for justice by investigating the disappearance of Julie Mao (Florence Faivre), a key player in the OPA (Outer Planets Alliance, a Belter activist group). But his motives are dubiousmuch of his search is misguided by fantasy, ignoring the Belter plight and rejecting his own heritage. Is Julie Mao our hero, then? She has a humanitarian streak, seen helping miners made sick from poor living conditions. But she joined a militant organization without questioning its methods, ultimately leading to her demise. As for the Belters, its indisputable that they are an oppressed group facing severe injustice, but they are hardly monolithic. Some have chosen violent means to achieve their goals by joining the OPAs terrorist cells, while others want legitimacy through formal negotiation.

The closest we have to heroes might be the crew of the Rocinante ship. This group of disparate people came together through unforeseen circumstances, each with different motivations for investigating the brewing conflicts between Earth, Mars and the Belters. What makes us root for them is not that they are consistently morally righteous (some of them possibly have sketchy backgrounds), but that they are fiercely committed to exposing the truth, whatever the truth may be.

This is not to say that there are no clear rights and wrongs in The Expanse universe. When the Belter miners are cruelly murdered after protesting inhumane conditions, we are meant to be appalled. When we see acts of terrorism that lead to the deaths of innocent civilians, we are meant to be horrified. There is no call to empathize with bigotry, or to tolerate murder. There is, however, a call to understand the root causes that underlie the institutions and systems that run the solar systemwhat privilege looks like, why terrorism happens. We are meant to confront evil and condemn it, but also to ask ourselves, and our leaders, What is really at work here? Only then can we move forward to better humanity as a whole.

And what might that look like? The Expanse has some ideas on that, too. All you have to do is take a look at the number of women in the series, all in positions of power, all with complex personalities. Theres the graceful and cruel Chrisjen Avasarala. Theres Naomi Nagata (Dominique Tipper), a capable engineer and natural leader aboard the Rocinante. Theres Theresa Yao (Jean Yoon), the stern captain of a Mars military vessel. On Ceres, theres Captain Shaddid (Lola Glaudini), head of Star Helix Security, as well as detective Octavia Muss (Athena Karkanis). And at the heart of the series mystery is the enigmatic Julia Mao. Daniel Abrahams, one of the authors of the books on which The Expanse is based, said in an interview with Tor.com that [i]t was always our intention to have a future world that included women who were strong as characters.

The shows not perfect, though. For instance, it still suffers from the Smurfette syndrome by often having just one strong female character within a group, resulting in a dearth of female relationships. But its a start, already miles ahead of a lot of current television. And if it seems like the mere existence of female leaders in a show is a low bar to set, youd be right. Unfortunately, such is the reality of a country that balked at the very idea of a woman with political ambitions assuming the mantle of the presidency.

Most of these characters are played by women of color, and the showrunners are enthusiastic in their embrace of a multicultural future both in the story and behind the scenes. In an interview with The Verge, Naren Shankar explained that he was committed to the vision of the books authors: The people who make it out into space, its not just going to be Neil Armstrong, clean-cut, classically white Americans. Its going to be Indian, Chinese, Russian, a mix of everybody, every ethnicity. And thats just going to melt and mingle. The very foundation of the shows futuristic premise is immigrationthe colonization of previously uninhabited planets means that everyone is essentially an immigrant.

But The Expanse isnt simply touting the idea of celebrating diversity. Its imagining a post-racial society. Indeed, inequality doesnt seem to exist between different races, or even different genders. Instead, we see a different kind of inequality, based on which planet one is from. Although the Belters, for example, are a racially diverse people, the group itself has a unique cultural identity. They are physically different (their bodies being taller and thinner due to low gravity conditions) and possess their own pidgin language (Belter Creole, a mixture of different languages that reflect the original settlers). Because of where they live and how they look, the Belters are essentially treated by the other planets as slave labor, inhuman even.

In the spirit of nuance, we should recognize that there is a danger in the aspiration for a post-racial world. Belters dont want to give up their identity so much as gain civil rights that are afforded to all humans on other planets. Its a multiracial society we need, not a homogenous one. Perhaps the lesson here is that inequality will always exist in some form or another when the privileged dont recognize marginalized groups. Perhaps this is the story that progressives want to be able to tella story that does not pit the white working class against the black working class, for instance, but instead unites both against the same system of economic oppression.

The Expanse shows us a possible future, a future in which women can be leaders without the bat of an eye, in which racially diverse groups can unite in common cause. But it is also a warning about keeping institutions in check, about recognizing inequality wherever it might exist, in order to avoid past mistakes. Whether it provides lessons on how to deal with autocracy, or simply provides hope and relief from our current situation, The Expanse is must-watch television for our time. And I didnt even mention the mysterious glowing blue stuff

Elena Zhang is a freelance writer based in Chicago. Follow her on Twitter at @EZhang77.

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In Syfy's The Expanse, Nuance Is the Antidote to Authoritarianism - Paste Magazine

Elon Musk, the founder of SpaceX and Tesla, has made trips to Trump Tower. He met with Trump and the Washington Post has ben reliably told, discussed Mars and public-private partnerships.

Elon Musk and SpaceX have the bold dream of colonizing Mars, and think they can launch the first human mission to the surface of the Red Planet as soon as 2024 when Trump, if reelected, would still be in the White House. (We understand that Musk also talked with Trump about other issues, including the need for a smart grid the kind of infrastructure that would give a boost to the solar energy business, in which Musk is a leader via his investments in the company Solar City.)

Trump seems to be cozying up to Elon Musk and is entertaining the idea of financing Musks Mars colonization project

Elon's Vision of the Mars Colony

Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.

Real Mars and Spacex Plans

The current Mars plan is:

The Flight Tank for the Interstellar Transport was the most important part of the announcement

The flight tank will actually be slightly longer than the development tank shown, but the same diameter.

That was built with latest and greatest carbon fiber prepreg. In theory, it should hold cryogenic propellant without leaking and without a sealing linker. Early tests are promising.

Will take it up to 2/3 of burst pressure on an ocean barge in the coming weeks.

The spaceship would be limited to around 5 g's nominal, but able to take peak loads 2 to 3 times higher without breaking up.

Booster would be nominal of 20 and maybe 30 to 40 without breaking up.

Spacex and Elon Musk have the 61 page presentation of the Interplanetary Transport System and the plan from early exploration to a sustainable colony on Mars

Spacex has built a full sized carbon composite fuel tank.

The Interplanetary Transport system can launch 550 tons to low earth orbit which is nearly four times as much as the Saturn V. It would be over four times as powerful as the SLS in the final version of the SLS

Next version of Falcon 9 will have uprated thrust

Final Falcon 9 has a lot of minor refinements that collectively are important, but uprated thrust and improved legs are the most significant.

Elon thinks the F9 boosters could be used almost indefinitely, so long as there is scheduled maintenance and careful inspections. Falcon 9 Block 5 -- the final version in the series -- is the one that has the most performance and is designed for easy reuse, so it just makes sense to focus on that long term and retire the earlier versions. Block 5 starts production in about 3 months and initial flight is in 6 to 8 months, so there isn't much point in ground testing Block 3 or 4 much beyond a few reflights.

Robert Zubrin, Longtime Mars Colonization advocate, gives a Critique of the SpaceX Interplanetary Transport System.

Zubrin was struck by many good and powerful ideas in the Musk plan. However, Musks plan assembled some of those good ideas in an extremely suboptimal way, making the proposed system impractical. Still, with some corrections, a system using the core concepts Musk laid out could be made attractive not just as an imaginative concept for the colonization of Mars, but as a means of meeting the nearer-at-hand challenge of enabling human expeditions to the planet.

Zubrin explains the conceptual flaws of the new SpaceX plan, showing how they can be corrected to benefit, first, the near-term goal of initiating human exploration of the Red Planet, and then, with a cost-effective base-building and settlement program, the more distant goal of future Mars colonization.

Robert Zubrin, a New Atlantis contributing editor, is president of Pioneer Energy of Lakewood, Colorado, and president of the Mars Society.

Highlights * Have the second stage go only out to the distance of the moon and return to enable 5 payloads to be sent instead of one * Leave the 100 person capsule on Mars and only have a small cabin return to earth * use the refueling in orbit and other optimizations to enable a Falcon Heavy to deliver 40 tons to Mars instead of 12 for exploration missions in 2018, 2020 etc... * Reusable first stage makes rocketplanes going anywhere point to point on Earth feasible. Falcon Heavy would have the capacity of a Boeing 737 and could travel in about one hour of time anywhere

There are videos of the Elon Musk presentation and an interview with Zubrin about the Musk plan at the bottom of the article

Design of the SpaceX Interplanetary Transport System

As described by Musk, the SpaceX ITS would consist of a very large two-stage fully-reusable launch system, powered by methane/oxygen chemical bipropellant. The suborbital first stage would have four times the takeoff thrust of a Saturn V (the huge rocket that sent the Apollo missions to the Moon). The second stage, which reaches orbit, would have the thrust of a single Saturn V. Together, the two stages could deliver a maximum payload of 550 tons to low Earth orbit (LEO), about four times the capacity of the Saturn V. (Note: All of the tons referenced in this article are metric tons.)

At the top of the rocket, the spaceship itself where some hundred passengers reside is inseparable from the second stage. (Contrast this with, for example, NASAs lunar missions, where each part of the system was discarded in turn until just the Command Module carried the Apollo astronauts back to Earth.) Since the second-stage-plus-spaceship will have used its fuel in getting to orbit, it would need to refuel in orbit, filling up with about 1,950 tons of propellant (which means that each launch carrying passengers would require four additional launches to deliver the necessary propellant). Once filled up, the spaceship can head to Mars.

The duration of the journey would of course depend on where Earth and Mars are in their orbits; the shortest one-way trip would be around 80 days, according to Musks presentation, and the longest would be around 150 days. (Musk stated that he thinks the architecture could be improved to reduce the trip to 60 or even 30 days.)

After landing on Mars and discharging its passengers, the ship would be refueled with methane/oxygen bipropellant made on the surface of Mars from Martian water and carbon dioxide, and then flown back to Earth orbit.

Zubrin's Problems with the Proposed Spacex System

The SpaceX plan as Musk described it contains nine notable features. If we examine each of these in turn, some of the strengths and weaknesses in the overall system will begin to present themselves.

1. Extremely large size. The proposed SpaceX launch system is four times bigger than a Saturn V rocket. This is a serious problem, because even with the companys impressively low development costs, SpaceX has no prospect of being able to afford the very large investment at least $10 billion required to develop a launch vehicle of this scale.

2. Use of methane/oxygen bipropellant for takeoff from Earth, trans-Mars injection, and direct return to Earth from the Martian surface. These ideas go together, and are very strong. Methane/oxygen is, after hydrogen/oxygen, the highest-performing practical propellant combination, and it is much more compact and storable than hydrogen/oxygen. It is very cheap, and is the easiest propellant to make on Mars. For over a quarter century, I have been a strong advocate of this design approach, making it a central feature of the Mars Direct mission architecture I first laid out in 1990 and described in my book The Case for Mars. However, it should be noted that while the manufacture of methane/oxygen from Martian carbon dioxide and water is certainly feasible, it is not without cost in effort, power, and capital facilities, and so the transportation system should be designed to keep this burden on the Mars base within manageable bounds.

3. The large scale manufacture of methane/oxygen bipropellant on the Martian surface from indigenous materials. Here I offer the same praise and the same note of caution as above. The use of in situ (that is, on-site) Martian resources makes the entire SpaceX plan possible, just as it is a central feature of my Mars Direct plan. But the scale of the entire mission architecture must be balanced with the production capacity that can realistically be established.

4. All flight systems are completely reusable. This is an important goal for minimizing costs, and SpaceX is already making substantial advances toward it by demonstrating the return and reuse of the first stage of its Falcon 9 launch vehicle. However, for a mission component to be considered reusable it doesnt necessarily need to be returned to Earth and launched again. In general, it can make more sense to find other ways to reuse components off Earth that are already in orbit or beyond. This idea is reflected in some parts of the new SpaceX plan such as refilling the second stage in low Earth orbit but, as we shall see, it is ignored elsewhere, at considerable cost to program effectiveness. Furthermore the rate at which systems can be reused must also be considered.

5. Refilling methane/oxygen propellant in the booster second stage in Earth orbit. Here Musk and his colleagues face a technical challenge, since transferring cryogenic fluids in zero gravity has never been done. The problem is that in zero gravity two-phase mixtures float around with gas and liquid mixed and scattered among each other, making it difficult to operate pumps, while the ultra-cold nature of cryogenic fluids precludes the use of flexible bladders to effect the fluid transfer. However, I believe this is a solvable problem and one well worth solving, both for the benefits it offers this mission architecture and for different designs we may see in the future.

6. Use of the second stage to fly all the way to the Martian surface and back. This is a very bad idea. For one thing, it entails sending a 7-million-pound-force thrust engine, which would weigh about 60 tons, and its large and massive accompanying tankage all the way from low Earth orbit to the surface of Mars, and then sending them back, at great cost to mission payload and at great burden to Mars base-propellant production facilities. Furthermore, it means that this very large and expensive piece of capital equipment can be used only once every four years (since the feasible windows for trips to and from Mars occur about every two years).

7. The sending of a large habitat on a roundtrip from Earth to Mars and back. This, too, is a very bad idea, because the habitat will get to be used only one way, once every four years. If we are building a Mars base or colonizing Mars, any large habitat sent to the planets surface should stay there so the colonists can use it for living quarters. Going to great expense to send a habitat to Mars only to return it to Earth empty makes no sense. Mars needs houses.

8. Quick trips to Mars. If we accept the optimistic estimates that Musk offered during his presentation, the SpaceX system would be capable of 115-day (average) one-way trips from Earth to Mars, a somewhat faster journey than other proposed mission architectures. But the speedier trips impose a great cost on payload capability. And they raise the price tag, thereby undermining the architectures professed purpose colonizing Mars since the primary requirement for colonization is to reduce cost sufficiently to make emigration affordable. Lets do some back-of-the-envelope calculations. Following the example of colonial America, lets pick as the affordability criterion the property liquidation of a middle-class household, or seven years pay for a working man (say about $300,000 in todays equivalent terms), a criterion with which Musk roughly concurs. Most middle-class householders would prefer to get to Mars in six months at the cost equivalent to one house instead of getting to Mars in four months at a cost equivalent to three houses. For immigrants, who will spend the rest of their lives on Mars, or even explorers who would spend 2.5 years on a round trip, the advantage of reaching Mars one-way in four months instead of six months is negligible and if shaving off two months would require a reduction in payload, meaning fewer provisions could be brought along, then the faster trip would be downright undesirable. Furthermore, the six-month transit is actually safer, because it is also the trajectory that loops back to Earth exactly two years after departure, so the Earth will be there to meet it. And trajectories involving faster flights to Mars will necessarily loop further out into space if the landing on Mars is aborted, and thus take longer than two years to get back to Earths orbit, making the free-return backup abort trajectory impossible. The claim that the SpaceX plan would be capable of 60-day (let alone 30-day) one-way transits to Mars is not credible.

9. The use of supersonic retropropulsion to achieve landing on Mars. This is a breakthrough concept for landing large payloads, one that SpaceX has demonstrated successfully in landing the first stages of its Falcon 9 on Earth. Its feasibility for Mars has thus been demonstrated in principle. It should be noted, however, that SpaceX is now proposing to scale up the landing propulsion system by about a factor of 50 and employing such a landing techniques adds to the propulsive requirement of the mission, making the (unnecessary) goal of quick trips even harder to achieve.

Improving the SpaceX ITS Plan

Taking the above points into consideration, some corrections for the flaws in the current ITS plan immediately suggest themselves:

A. Instead of hauling the massive second stage of the launch vehicle all the way to Mars, the spacecraft should separate from it just before Earth escape. In this case, instead of flying all the way to Mars and back over 2.5 years, the second stage would fly out only about as far as the Moon, and return to aerobrake into Earth orbit a week after departure. If the refilling process could be done expeditiously, say in a week, it might thus be possible to use the second stage five times every mission opportunity (assuming a launch window of about two months), instead of once every other mission opportunity. This would increase the net use of the second stage propulsion system by a factor of 10, allowing five payloads to be delivered to Mars every opportunity using only one such system, instead of the ten required by the ITS baseline design. Without the giant second stage, the spaceship would then perform the remaining propulsive maneuver to fly to and land on Mars.

B. Instead of sending the very large hundred-person habitat back to Earth after landing it on Mars, it would stay on Mars, where it could be repurposed as a Mars surface habitat something that the settlers would surely find extremely useful. Its modest propulsive stage could be repurposed as a surface-to-surface long-range flight system, or scrapped to provide material to meet other needs of the people living on Mars. If the propulsive system must be sent back to Earth, it should return with only a small cabin for the pilots and such colonists as want to call it quits. Such a procedure would greatly increase the payload capability of the ITS system while reducing its propellant-production burden on the Mars base.

C. As a result of not sending the very large second stage propulsion system to the Martian surface and not sending the large habitat back from the Martian surface, the total payload available to send one-way to Mars is greatly increased while the propellant production requirements on Mars would be greatly reduced.

D. The notion of sacrificing payload to achieve one-way average transit times substantially below six months should be abandoned. However, if the goal of quick trips is retained, then the corrections specified above would make it much more feasible, greatly increasing payload and decreasing trip time compared to what is possible with the original approach.

Changing the plan in the ways described above would greatly improve the performance of the ITS. This is because the ITS in its original form is not designed to achieve the mission of inexpensively sending colonists and payloads to Mars. Rather, it is designed to achieve the science-fiction vision of the giant interplanetary spaceship. This is a fundamental mistake, although the temptation is understandable. (A similar visionary impulse influenced the design of NASAs space shuttle, with significant disadvantage to its performance as an Earth-to-orbit payload delivery system.) The central requirement of human Mars missions is not to create or operate giant spaceships. Rather, it is to send payloads from Earth to Mars capable of supporting groups of people, and then to send back such payloads as are necessary.

To put it another way: The visionary goal might be to create spaceships, but the rational goal is to send payloads.

Alternative Versions of the SpaceX ITS Plan

To get a sense of some of the benefits that would come from making the changes I [Zubrin] outlined above, lets make some estimates. In the table below, I [Zubrin] compare six versions of the ITS plan, half based on the visionary form that Elon Musk sketched out (called the Original or O design in the table) and half incorporating the alterations I [Zubrin] have suggested (the Revised or R designs).

Our starting assumptions: The ship begins the mission in a circular low Earth orbit with an altitude of 350 kilometers and an associated orbital velocity of 7.7 kilometers per second (km/s). Escape velocity for such a ship would be 10.9 km/s, so applying a velocity change (DV) of 3 km/s would still keep it in a highly elliptical orbit bound to the Earth. Adding another 1.2 km/s would give its payload a perigee velocity of 12.1 km/s, sufficient to send it on a six-month trajectory to Mars, with a two-year free-return option to Earth. (In calculating trip times to Mars, we assume average mission opportunities. In practice some would reach Mars sooner, some later, depending on the launch year, but all would maintain the two-year free return.) We assume a further 1.3 km/s to be required for midcourse corrections and landing using supersonic retropropulsion. For direct return to Earth from the Martian surface, we assume a total velocity change of 6.6 km/s to be required. In all cases, an exhaust velocity of 3.74 km/s (that is, a specific impulse of 382 s) for the methane/oxygen propulsion, and a mass of 2 tons of habitat mass per passenger are assumed. A maximum booster second-stage tank capacity of 1,950 tons is assumed, in accordance with the design data in Musks presentation.

Using the improved plan to send 40 tons (3.3 times more) to Mars with Falcon Heavy

Consider what this revised version of the ITS plan would look like in practice, if it were used not for settling Mars but for the nearer-at-hand task of exploring Mars. If a SpaceX Falcon Heavy launch vehicle were used to send payloads directly from Earth, it could land only about 12 tons on Mars. (This is roughly what SpaceX is planning on doing in an unmanned Red Dragon mission as soon as 2018.) While it is possible to design a minimal manned Mars expedition around such a limited payload capability, such mission plans are suboptimal. But if instead, following the ITS concept, the upper stage of the Falcon Heavy booster were refueled in low Earth orbit, it could be used to land as much as 40 tons on Mars, which would suffice for an excellent human exploration mission. Thus, if booster second stages can be refilled in orbit, the size of the launch vehicle required for a small Mars exploration mission could be reduced by about a factor of three.

In all of the ITS variants discussed here, the entire flight hardware set would be fully reusable, enabling low-cost support of a permanent and growing Mars base. However, complete reusability is not a requirement for the initial exploration missions to Mars; it could be phased in as technological abilities improved. Furthermore, while the Falcon Heavy as currently designed uses kerosene/oxygen propulsion in all stages, not methane/oxygen, in the revised ITS plan laid out above only the propulsion system in the trans-Mars ship needs to be methane/oxygen, while both stages of the booster can use any sort of propellant. This makes the problem of refilling the second stage on orbit much simpler, because kerosene is not cryogenic, and thus can be transferred in zero gravity using flexible bladders, while liquid oxygen is paramagnetic, and so can be settled on the pumps side of the tank using magnets.

Dawn of the Spaceplanes

Toward the end of his presentation, Musk briefly suggested that one way to fund the development of the ITS might be to use it as a system for rapid, long-distance, point-to-point travel on Earth. This is actually a very exciting possibility, although I would add the qualifier that such a system would not be the ITS as described, but a scaled-down related system, one adapted to the terrestrial travel application.

For a rocketplane to travel halfway around the world would require a DV of about 7 km/s (6 km/s in physical velocity, and 1 km/s in liftoff gravity and drag losses). Assuming methane/oxygen propellant with an exhaust velocity of 3.4 km/s (it would be lower for a rocketplane than for a space vehicle, because exhaust velocity is reduced by surrounding air), such a vehicle, if designed as a single stage, would need to have a mass ratio of about 8, which means that only 12 percent of its takeoff mass could be solid material, accounting for all structures, while the rest would be propellant. On the other hand, if the rocketplane were boosted toward space by a reusable first stage that accomplished the first 3 km/s of the required DV, the flight vehicle would only need a mass ratio of about 3, allowing 34 percent of it to be structure. This reduction of the propellant-to-structure ratio from 7:1 down to 2:1 is the difference between a feasible system and an infeasible one.

In short, what Musk has done by making reusable first stages a reality is to make rocketplanes possible. But there is no need to wait for 500-ton-to-orbit transports. In fact, his Falcon 9 reusable first stage, which is already in operation, could enable globe-spanning rocketplanes with capacities comparable to the DC-3, while the planned Falcon Heavy (or New Glenn) launch vehicles could make possible rocketplanes with the capacity of a Boeing 737.

Nextbigfuture notes that reusable first stages are now technically functioning but safety and reliability would need to be improved by about 1000 to 10,000 times for point to point manned travel.

SOURCES- Spacex, Zubrin, the New Atlantis

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Trump may fund the Spacex Mars Colonization plan - Next Big Future