Showing posts from July, 2010

Coding Orbital Mechanics

I forget what inspired me, probably discussions about propellant depots, but after an hour of two playing around in the great spaceflight simulator Orbiter I decided to give the old orbital mechanics another go.

I've written dynamic physics simulators before which have really nice accuracy and can handle the big numbers required for orbital simulations, including three body problems, but I never managed to tackle the classical orbital mechanics - too much Greek terminology I guess - until today.

I set myself a somewhat difficult task:

Given a position vector r and a velocity vector v, somewhere above a reference (say, a planetary body) calculate all the required classical orbital elements:

a - semi-major axis
e - eccentricity
i - inclination
l - longitude of the ascending node
w - argument of periapsis
t - true anomaly

There's others, but they can be derived from these. You'll also note I haven't used any Greek letters that my keyboard doesn't have. I can also do t…

Dr Paul Spudis Responds - Sorta

I thank Dr Paul Spudis for responding. His post isn't addressed to me but it certainly appears to be directed at me.

Clearly if we don’t go to the Moon with people or machines, there is no way to use the abundant water, metals, and other lunar surface materials to create new capabilities in space. Supporters of the new path suggest instead that we can obtain all the materials we want from near-Earth asteroids

.. in my dreams! Us asteroid mining advocates are a minority who have been swept aside in this debate. Asteroids are a "stepping stone" to Mars, not a destination. As Clark puts it:

As pointed out many times here, the main impetus for the Flexible Path option was simply to have useful and interesting in-space missions underway while landing and surface systems for Moon and/or Mars were in development.

Spudis also makes good points about the difficulty of extracting resources from asteroids. This is often cited as justification for human missions. What he doesn…

Book Of The Week: Kim Stanley Robinson's Mars Trilogy

The Book Of The Week this week is Kim Stanley Robinson's "Red Mars", "Green Mars", "Blue Mars". This is often referred to as the Mars Trilogy, but none of these books are about Mars. There's plenty of awesome scientifically accurate detail in these books on Mars geology, the moons of Mars, Mars colonization, Mars terraforming, and even some interesting speculation about Mars native life and building a space elevator on Mars. The books are certainly set on Mars but that's as far as it goes. In my opinion, these books are as much about Mars as Hamlet is about Denmark.

These books are about politics, the real kind, and what happens when it devolves into war. The books start with group dynamics, petty infighting, the formation of camps and the inevitable fracturing of community. The lines are: those who want to terraform Mars and those who want to keep Mars red. But the battle lines don't really matter, what was shocking was how quick…

Misrepresenting The Gap

Ever get that feeling you're shouting into the void? Rand Simberg, someone who's opinion on space I truly value, has written an article on The Gap, and taken the well trod path of how bad it is to be reliant on the damn Ruskies.

With the coming retirement of the Space Shuttle, the most immediate issue in human spaceflight is how to get U.S. crews to the International Space Station.

When the decision was made in 2004 to retire the shuttle, the plan was to have a small "gap" starting this year, during which the Russians would provide this service, as they did for the two-and-a-half-year period after Columbia was lost.

But if lawmakers in the House have their way, we could be buying rides from Russia to the space station for the foreseeable future.

Argh. Rand, you know better, so I'm just going to have to assume you're playing down to the saps who read AOL News (and I imagine they are saps, cause who reads that?). As you know, the Soyuz has been used to carry…

Hating On Propellant Depots

Dan Adamo is a retired flight dynamics officer for the Shuttle program and does space mission trajectory, design and operations in his sleep. I recently saw him put together a design reference mission for a human mission to the moons of Mars, for fun, using only well understood technology. Back in February he did a Space Show Classroom where he discussed many topics and once again demonstrated his effortless grasp of orbital dynamics.

A listener asked about propellant depots and Adamo answered with what I think is the most articulate objection to the concept of low earth orbit propellant depots. He went on to talk more favorably about propellant depots at Lagrangian points and on the surface of destinations such as the Moon and Mars, but I think his objections are more interesting.

Starting from the ground up, here's where I have problems with propellant depots, in low Earth orbit.

Once you establish the depot, it can be empty for all I care at this point, but once you estab…

My Reason For Human Lunar Return

Why go back to the Moon?

I've asked that question a lot, and I've gotten a variety of answers.

There's a lot of nice resources on the Moon and the energy requirements to lift them from the Moon is a lot less than required to lift them from the Earth. There's water, which can be used for propellant, and there's metals, both in the lunar regolith and in more significant deposits from asteroid impacts.. but I disagree that we need humans to retrieve those resources.

The Apollo program only scratched the surface (literally) on lunar science. There's a whole lot of mysteries that lunar geologists don't have good answers for: nonmare domes, rilles, potentially active volcanic vents, the entire far side, and permanently shadowed craters.. but I again disagree that we need humans to do that science, and if NASA was at all serious about it they would have sent at least one rover to the Moon ever.

I have advocated the viewpoint that what should motivate human space…

"Access To Space"

Andre Bormanis has an article over at The Space Review which includes this nugget:

The US frequently partners with other countries and international organizations on space missions, primarily in the field of robotic exploration. Partnering in the development of manned systems has been resisted because of a belief, held deeply by many in government and among the public, that the US needs to have independent human access to space to maintain its status as a world power. If the Russians and Chinese can send people into orbit, so the reasoning goes, the US must as well, or risk being perceived as a declining power on the world stage.

Oh, is that what "access to space" means?

Well, as someone who is outside the US, I feel I can safely say: no-one cares. Yes, "soft power" exists, but no-one knows the names of astronauts anymore - they're just government employees who go up to an incomprehensible space station to pretend they're doing Important Work that has no re…

CCDev Is Dead

Ok, I don't usually write these sorts of things, but I think this is so incredibly terrible news that I feel the need to vent. The NASA Authorization Act of 2010 kills the commercial crew development program, while simultaneously killing any chance of funding SpaceX's COTS-D option. It contains these lies:

Sec. 241. Affirmation of Policy

Reaffirms the policy of making use of United States commercially provided International Space Station crew transport and crew rescue services; limiting the use of the government system to non-ISS missions once commercial crew transport and crew rescue services meeting safety requirements become operational; and facilitating the transfer of NASA-developed technologies to United States commercial orbital human space transportation companies.
All politicians lie, it's what they do, but it would be good if they could at least be consistent in the same document.  What follows in Sec 242 is a long list of restrictions to make it completely impr…

What Is The Gap?

I don't even know anymore. Buzz Aldrin has written another article, this time over at the Huffington Post.

A number of my former colleagues, and other critics, have expressed concerns about the plan, and in particular, they express grave reservations about 'the Gap' -- the end of the Space Shuttle Program, and the inability for the US to provide human access to space -- save for limited flight opportunities and capabilities with our Russian partners, pending the maturing of the commercial space transportation capabilities, or other future systems to meet these needs.

So it's about "human access to space". Ok, to do what? Why do you want human access to space? What's the point of it? Unless you address that question you can't seriously talk about what kind of access to space you need. Will suborbital access do? No? Ok, how about one orbit? No? Ok, how about 2 days? No? How about 2 weeks, the endurance of the shuttle? No? Oh, permanent acc…

A Likely Scenario

I was recently asked, "if a killer asteroid was approaching Earth, how much would they actually tell us?" This is my response.

They'd tell you numbers which you wouldn't understand. Then the pundits would turn those numbers into something they can scare you with, probably overblowing the threat while they do so, and Concerned Citizens would go to their Congressmen demanding answers. NASA would provide those answers.. in a completely unintelligible way, and someone would interpret those answers as dismissing the threat. Then there'd be a big argument over whether it's a threat or isn't it.

Eventually one of the egg heads with a wife will get a lecture about talking like a normal person once in a while and a press statement would be released saying exactly how likely and excessive the threat is (after it went through a few committees to ensure it was easy enough to understand, and defend). By this time the media will be completely bored with the story and …

How Near Are The Near-Earth Asteroids?

Back in 1978, following three successful free flights of Space Shuttle Enterprise the year before and the first lift-off of Space Shuttle Columbia only 3 years away, planetary scientist Gene Shoemaker and astronomer Eleanor Helin collaborated on a paper which presented the then shocking conclusion that some near-earth asteroids required less delta-v to reach than Mars. The near-term availability of the Space Shuttle was key, as the high flight-rate it promised meant a manned mission to an asteroid could be staged in low Earth orbit for as little as 23 flights. At the time, it wasn't unreasonable to suggest that within a few years that would be as little as 6 months of staging, and the vehicle would be reusable!

Of course, the Shuttle's flight rate never got that high, and today's mission designs to Mars are measured in International Space Station masses to remind us of how long it takes to amass payload in orbit.

This paper, however, remains important for the math it co…

Book Of The Week: Peter F. Hamilton's "Fallen Dragon"

The Book Of The Week this week is Peter F. Hamilton's "Fallen Dragon". Although there's some similarities to military tales like Starship Troopers, the book is primarily a commentary on the ever encroaching power of multi-national corporations on our society and the individualist to community to national government struggles to live with it, along with some transhumanist alternatives.

Corporations in the future described by the book have taken over space colonization and found a somewhat inelegant solution to the problem of how to turn a profit: armed robbery. Of course, legally they're on sturdy ground - euphemistically referring to the practice as "asset realization" - but it's nothing more than tax extraction through force and so serves as a neat covert commentary on the origins of government power.

Hamilton's gift is his efficiency of description, and with space technology he manages to simultaneously summarize the great concepts for the…

The Future Mines Of Humanity

Dr Phil Harris is a Moon First space advocate and a published and acclaimed author. In his book Space Enterprise: Living and Working Offworld in the 21st Century, he goes into exquisite detail of the challenges and the bounties of industrializing the lunar surface.

In early January of this year Harris authored a special White House strategy paper [redistributed with permission] which recommended a pushing forward on the Vision For Space Exploration, or at least the Moon focused vision that came out of it. He makes it very clear that the reason to go back to the Moon is to get resources and reduce the national debt.

Now is the time to enlighten our nation's citizens of the vast resources to be tapped on the Moon. We could not only mine the lunar surface for valuable minerals and gems, but we could use its water and regolith to support lunar industrialization and settlement!

Those last two words are the only mention of settlement in the entire paper - so this is an economic argume…

Desperately Seeking: Moon First Advocate

As it seems Paul Spudis isn't going to respond I am left without a sparring partner. Anyone who wants to pick up the gloves and make the case for returning to the Moon, come at it. The ground rules are simple: you must make an argument as to why we should return to the Moon first. It would also be good if you could explain how NASA can do it within a time frame that can be sold politically and within the current budget profile, but I'll settle for a why that makes sense. Note that if you just preach the dogma of someone else, you're unlikely to be able to defend it, so, please, only apply if you've got the stones.

Space Crack

Back in 2006 Elon Musk famously said:
"I don't believe in the mining of stuff in space. The transportation costs are so horrendously high that I don't think there's anything… if there were packages of purified crack cocaine in orbit right now, I'm not sure it would be financially viable to go and retrieve them"Which is ironic when you consider that it was at the unveiling of the Dragon that he made this famous quote. According to a recent presentation a Falcon 9/Dragon flight for robotic servicing would cost ~$80M. This includes launch vehicle, Dragon spacecraft, operations and recovery. It doesn't include the robotic arm, so let's include $5M for that.

The Dragon has a downmass of 3000kg. Per kg, that's $28,330. The street value of cocaine hydrochloride powder is $80-$100 per gram, or ~$80,000 per kg.

As such, in just 4 years SpaceX has managed to make the Space Crack market profitable.

(and Platinum $49,187/kg, and Gold $38,838/kg).

Flight To An Asteroid With SpaceX Hardware

John Hare has an article about commercial beyond Earth orbit exploration in a world where cheap access to space has lowered the cost of a kg to LEO to $1000 or less. But I think it begs the question, how much does it cost now?

Warning: contains Machiavellian humor.

The biggest problem with commercial human beyond LEO flight right now is the lack of an affordable LH2 upper stage. In SpaceX terms: they don't have Raptor yet. But hey, no-one ever said you have to use LH2/LOX stages to go beyond LEO.

If you're aiming at an asteroid at an optimal time, there's at least one target you can hit with only 2.8km/s of delta-v from LEO, and 1km/s of delta-v to rendezvous with the asteroid, 2006 RH120. (Note that you can divide this up any way that makes sense to you, but more than 1km/s of delta-v at rendezvous is probably undesirable. For a flyby of 2006 RH120 you need 3.733km/s). See this list. Personally, I'd rather aim at 2009 BD as it is almost always "close" …

Book Of The Week: Stephen Baxter's "Manifold Time"

The Book Of The Week this week is Stephen Baxter's "Manifold Time". The reason I love this book: rugged individualism. Sure, there's other great threads in this book and some interesting cosmology, but the memorable part of this story is the huge balls on the main character.

Reid Malenfant is an unapologetic space cadet and serial entrepreneur, who has a plan just crazy enough to work: he's going to claim an asteroid. With a shout out to Robert Heinlein he ignores a recently passed law preventing his liftoff, not to mention a few laws related to non-proliferation of nuclear materials, and heads off to his very own squid-infested home among the stars.

Oh, I didn't explain the squids did I? :)

Buy it on Amazon.

Imagine Wernher von Braun Had Won

Imagine the Apollo follow-on wasn't Skylab, it was the construction of a Mars ship.

Back in the early 70s they had absolutely no appreciation for the radiation environment. Aerobraking on Mars was considered unworkable by some and trivial by others - Viking would prove both wrong but not until the mid 70s. Nuclear thermal was already a political dead duck but maybe it could have been resuscitated for an EOR mission configuration, but it's still impulse, ion engines were shelved in the early 60s as impractical, hall effect thrusters were secret Russian business. Long duration spaceflight was a backwater of scientific knowledge, as was most space medicine - some would say it still is - the bone loss problem was certainly an unknown unknown. In-situ resource utilization was a complete non-starter.

So, the good news is they wouldn't try to build Battlestar Galactica. They'd go with a capsule and a lander, but bigger and heavier than the Apollo LM and with a heat shiel…

Dr Paul Spudis Continues To Baffle Me

No-one ever accused me of being subtle. I'm happy to clearly state my opinion and support it with what, I hope, is persuasive argument. As a result, subtle people tend to confuse me. That's right, along with all the other things I have accused Paul Spudis of over the last year, I'm now accusing him of being subtle: painfully subtle.

Over at Spudis's blog he rants and raves over the definition of "misconception" and manages to fit in a plug for what I guess is his position..

The purpose of lunar return under the VSE is not to collect rocks or relive past space glories. Simply put, because we can't take everything with us, humans must learn to use what we find in space to create new space faring capabilities, starting on the Moon. And our goals are not simply Mars, but everywhere – wherever human presence is needed or desired. Using the resources of the Moon (specifically, making consumables and propellant from lunar materials) enables routine access …

Walt Cunningham Advocates New NASA Goals

On the 4th of July former astronaut Walt Cunningham appeared on the Talking Space podcast to discuss NASA's future and other topics.

Cunningham fundamentally disagrees with everything NASA is doing under the new administration. He thinks the shuttles should not be retired (although he acknowledges that the new administration inherited that situation) and should be evolved into a new vehicle. He accuses the White House administration of just wanting to cut the budget of human spaceflight altogether and alludes to activities which support this theory.

Back in March he sent a similar statement to a public mailing list I'm (still unfortunately) on:

"Lest there be any mistake, I believe Obama's removal of NASA from operation of the agency's own human space program is a major mistake. It was not an effort to improve our space program; it was purely to cut expenditures on something in which Obama has no belief. It was the second worst decision in NASA's history; the…

Living Inside An Asteroid

Deriders of the new NASA direction have latched on to the announced human asteroid mission in the 2025 timeframe as something they "can't imagine" and therefore is not worth doing. Of course, the administration is talking up the "science" that can be done on an asteroid, and how this could better inform us should the need arise to divert or destroy one that threatens Earth. This is good politics as nothing motivates like fear, but for those of us who think the human spaceflight program is really about preparing us to live at the future homes of humanity, asteroids would seem to be just a stop on the way - I disagree.

As I've written previously, the new NASA direction isn't about asteroids - it isn't about destinations - it's about going and specifically, it's about going to Mars. I'm not sure NASA knows yet why they're going to Mars, but they're focusing on the technology to get there and get back safely, and some of the stepp…

The Completely False Choice

During an interview on The Space Show Jeff Greason described the Flexible Path as a pragmatic approach to human space exploration when considering NASA's limited budget. Towards the end he says:

The question is not "do we or don't we go to the Moon", that's a completely false choice. The question is do we structure the program, for the same money, in a way in which - in addition to going back to the Moon - we get asteroids, Lagrange points, maybe a Mars flyby, and we build up deep space experience that we're going to need for Mars, instead of waiting 20 years and hoping that the public's enthusiasm can be sustained.

The message here is that the Moon and Mars both require landers and it's hard enough just trying to get there with a limited budget. So, assuming NASA isn't going to get double as much money, it needs to find a way to do with what it's got. This is a fiscal reality. Those who say "Constellation can be fixed" or who sa…

There's No Business Like Show Business

That is NASA's attempt at public outreach.. and I've yet to see a single newspaper link to it or report it. If you watch it, you can see why. Whenever Lori Garver or Rob Braun is about to explain what the program is about they get cut off.

It's all so glossy and vague.. most the time I think they juxtapose the wrong images with the words.. like "we plan nothing less than to create the future of spaceflight, now" cut to a shot of the Shuttle liftoff.. wtf? "After the safe and planned retirement of the space shuttle fleet.." ohhhh, is that what that shot is for? Wow, someone failed film school.

Then they gotta say some stuff about the ISS and how great it is and fuels the international cooperation and blah blah blah. And while you're being bored by justifications for the ISS program they slip in "we're trying to make this more commercial" and private companies. Yawn, sorry, I fell asleep there, did you say NASA will focus on be…

Reselling Mike Griffin

Back in 2005 Peter A. Taylor wrote on then current NASA Administrator Mike Griffin's revisioning of the Vision for Space Exploration. In many ways, Taylor's interpretation of Griffin's vision is reflected in the new NASA direction, and one has to wonder if the opponents of "Obama Space" have any idea how much pedigree that vision really has.

As Taylor writes, it all goes back to the intricately detailed study "Extending Human Presence into the Solar System" (July 2004, Planetary Society) co-authored by Owen Garriott (that's Richard Garriott's Dad!), Bill Claybaugh (now senior director of human spaceflight for Orbital Sciences), John Garvey (Garvey Spacecraft Corporation), Tom Jones (the former astronaut, not the sexy singer), Charles Kohlhase (JPL), Bruce McCandless II (another former astronaut), Will O’Neil (independent defense and space consultant), Paul A. Penzo (former JPL, now at Global Aerospace), and Mike Griffin.

The paper advocates a …

Jeff Greason Answers: Why Humans In Space?

In a video over at the XCOR Aerospace website, founder Jeff Greason describes, among other things, what human spaceflight should be about and why NASA should be doing it.

I believe passionately in the value of humans in space.

One of the most overlooked findings on the Augustine committee, I think, was an inquiry into the reasons why this is so.

Nobody in Congress could care less why this is so from what I see publicly, but if you don't know why you're doing what you're doing it's very hard to discuss what the best way is to do it.

You get science from people being in space. It's a myth that you don't. You know, ask the guys at JPL if they would like to have human beings on some of these targets - they'll tell you "absolutely".

But that's not the reason you do it. That's just a benefit you get.

You get international good will from doing things in space. Especially if you do it with an international component. You know, ask the guys who …