Wednesday, March 8, 2017

Blue Origin's New Glen rocket

This is an exciting time to be someone interested in spaceflight.  Not as exciting as the original space race, of course, but hopefully we'll get close within the coming decade.  SpaceX has been making a lot of news with its landings of the first stages of its rockets after using them and its big plans for future Mars missionsh and sending people around the moon.

The United Launch Alliance, which handles most of the government's launches and has a very good reliability record, also has some fairly ambitions plans it's announced involving the development of the space near Earth and it's next generation upper stage.  But probably the most exciting competitor to SpaceX right now (besides NASA) is Blue Origin.

SpaceX has its Falcon 9 which is launching satellites now and its more ambitious and out there ITS.  Blue Origin has until now had its New Shepard rocket for shuttling tourists up to space briefly but recently its been talking more about the New Glenn, a vehicle somewhere in ambition between SpaceX's existing and imagined rockets.  You can watch the video Blue put together about the New Glenn here.

This is a rather large rocket.  Not quite Saturn V large, as you can see here, but close.
There are apparently two different configurations it can fly in, one with a third stage and one without.  The two stage version is the one they made the video of and which they provided some more details for recently.  It's not much taller than a Falcon 9 but is much thicker, at 7 meters in diameter to the Falcon 9's 3.7 meters.   The Falcon had to be long and thin in order for SpaceX to ship it by truck all the way from California, where they are made, to Florida where they are launched.  Blue Origin has invested in a big factory in Florida near their launch pad so that isn't as much of a concern for them.

There are still a number of unkowns for the 2 stage New Glenn but we know how large a payload it can send into low Earth orbit, 45 tons, and how much it send on its way toward geostationary orbit, 13 tons.  This compares with 22.8 and 8.3 tons for the Falcon 9.  It's interesting that the numbers are so far apart for the New Glenn compared to the Falcon 9 but there's a reason for that.

Remember from back when I blogged about rocket performance that the amount you can accelerate for a rocket is related to how much of the combined rocket/payload mass is fuel.  The New Glenn seems to have a fairly heavy rocket engine for its second stage.  That means that it can lift a heavy payload into orbit quickly before gravity has had time to cause too much in the way of a slowdown.  But it also means that the total non-payload mass of the second stage is higher so even if the payload goes down to something fairly small the engine and other weights will still prevent the overall mass ratio from getting too high.  Hence the stage will have a hard time getting a reasonable payload into higher energy orbits.

I suppose that has to do with the optional 3rd stage.  If you're going to have a third stage you want your second stage to burn it's fuel fairly quickly with a high power engine so that the third stage can get to its business.  I'd imagine that the adding the third stage would add a bit to the low Earth orbit payload of one of these rockets but would add far more to how much it can get into a GTO orbit.

The other big difference I noticed, besides sizes, between New Glenn and Falcon 9 was how the rockets are supposed to land.  SpaceX likes to land the Falcon 9 back on land when possible but also has a barge that floats out in the sea for the rocket to land on if the Falcon 9 doesn't have enough extra fuel after getting its payload to space to send itself all the way back to the pad it took off from.  SpaceX is clearly thinking about pad landings as what they want to do in the future in order to quickly refurbish the rocket and launch again.

For New Glenn landing at sea seems to be the idea with a return to the launch site being something that they're not really considering seriously.  You can see this in the ship that they're using.   Rather than cheap barge they seem, in the video, to be thinking about using a second-hand tanker with a big landing pad re-fitted onto the top.  The side-thrusters on a tanker aren't very powerful and so it would have to be moving forward to keep good control of its orientation to provide a stable landing site but overall it can give a much bigger target for the rocket to land on and in heavier seas too.  Also, it should be able to sail back to port much more quickly than SpaceX's barge can.  On the other hand it will probably be a lot more expensive to operate too.

So Blue Origin is investing in a bigger, more powerful ship to make landing at sea easier and SpaceX is mostly thinking about returning to land with sea landings something of an afterthought.  I suppose time will tell which is a better strategy.

Thursday, February 9, 2017

Hydrogen versus gas in cars

For a long time people have talked about the idea of using hydrogen to fuel our transportation systems.  There are some obvious advantages to this.  When you burn hydrogen you don't release any CO2, the hydrogen combines with oxygen to form simple water.  Batteries like you'd find in an electric car also store and release energy without emitting CO2 but those don't hold as much energy as the equivalent weight of hydrogen.  Hydrogen theoretically stores 40,000 Wh/kg whereas even a good battery like the one used in a Tesla only stores  100 Wh/kg.  The theoretical values aren't the whole story since converting hydrogen to motive force is less efficient than converting charge in a battery.  And also you need tanks to store the hydrogen which I'll come back to later.  But those don't overcome the magnitude of the difference and long range hydrogen cars are feasible in a way that long range electric cars aren't.

On the other hand hydrogen has some big problems compared to batteries or other fuels.  At room temperature and pressure hydrogen only nets you 3 Wh/L compared to 9,500 Wh/L for gasoline or roughly 500 Wh/L for lithium ion batteries (I couldn't find Tesla's exact number).  To make hydrogen feasible you have to compress it a lot.  According to the ideal gas law you'd need to keep your hydrogen at 450 bars to get up to a good-for-long-range 1,250 Wh/L but Wikipedia tells me it's really 690 for some reason.  690 bars is a lot, requiring a very heavy pressure vessel if it's going to be robust to car crashes.  For a 10 L, .3 kg tank of hydrogen the back of my envelope tells me you'd need something like 100 kg of steel.  I have no idea if that's actually accurate but it suggests that hydrogen's range advantage over batteries isn't so very great.

Lets say you've got a bunch of the hydrogen you were going to put into your car.  There are other things you can do with it instead.  Something that's been used industrially for over a hundred years is the Sabatier reaction, turning hydrogen and carbon dioxide into methane.  Methane is also a gas, like hydrogen, but it's a far denser one cutting down on the pressure needed to get a tank of it into something that can fit into a car.   Some energy is lost in the conversion but only around 25%.  And that's just the 100 year old technology.  Turning hydrogen and carbon dioxide into methanol, ethanol, or conventional hydrocarbons is something that currently exists in pilot plants.  A development would be needed to make this practical to generate enough to replace all our current gasoline production but it would be far, far easier than converting all our cars, infrastructure, etc to run on hydrogen.

But of course this scheme is currently missing one of the chief advantages that both electric and hydrogen cars enjoy: the federal subsidy for zero-emission vehicles.  A vehicle running on synthetic gas might absorb a gram of CO2 from the air for every gram that comes out its tailpipe but there's still CO2 coming out of its tailpipe.  So legally it's not in the right category to benefit from existing government subsidies.  Maybe if this caught on the government might do something, who knows.  But really this sort of issue is why I'm much prefer a carbon tax or some other sort of universal and evenhanded program rather than our current mostly ad hoc system for trying to reduce carbon emissions.  Because really, nobody knows how many other situations like this there are where a fixation on details distracts us from the problem of reducing the amount of carbon dioxide in the air.

Monday, January 23, 2017

Collected book reviews

At Bill Gates's recommendation I recently read  The Grid by Gretchen Bakke.  There's been a lot of talk recently about the US having an infrastructure problem but mostly it's in the context of our roads and bridges.  But really our electrical grid is also very important for modern life and impending changes to electricity generation look to increase the strain on the grid.  The cost of solar electricity on average has been plunging but the demand for electricity doesn't go down when a cloud passes over a solar farm.  We really want to be spreading out fluctuations generation between further flung power plants but to do that we need to build new, better, power lines.  There's also a good history of early electrical innovation though I was already familiar with much of it.

Donald Trump's election finally prompted me to get around to reading The Revolt of the Public by Martin Gurri.  He wrote about how social media has made the failures of expert opinion more apparent to the public and given the public the confidence to challenge the rule of existing experts in many areas and has ignited political protests around the world.  Before reading this book I hadn't ever stepped back and taken stock of the wide variety of protests that have taken place in areas as diverse as Tunis, Spain, and the US.  I suppose I'd liken myself to a frog who didn't realize the water it's in is heating up.

As people's political self efficacy, to use a phrase from my excellent high school civics textbook, grows they protest mistakes but don't have any unified theory of what to change specifically - just the notion that it must be possible to do better.  Apart from protests this means a lot of politicians who are outsiders or who can present themselves as outsiders get elected.  Obama painted himself as an outsider.  Trump did too.  I can only hope that the democrats get some movie star or other for 2012?  In any event I guess this makes the Greek referendum I was confused about make more sense.  The people conducting it were newly in power so the voters trusted them.  But the forces shaping political results will continue to mostly so I fear we're all going to keep being disappointed.  And I should really write a post at some point on veto points and legitimacy.

Another book I finished recently was The Gene: An Intimate History by Siddhartha Mukherjee, also recommended by Bill Gates.  I found the start a bit dull as I'd already been familiar with the story of Darwin and Mendel.  But as we got into the 20th century I was fascinated by all the techniques used to extend our knowledge of genetics and all the stories I hadn't heard before.  I wasn't particularly impressed by his analysis of the implications of genetic technologies.  For instance in one place he implicitly seemed to assume abortion is murder but in another place he implicitly assumed it isn't without noticing.  In his description of the first trial of a genetic therapy he also skimmed over what seemed, to me, to be the most perverse logic I've ever heard of outside a Kafka novel.  The idea was that if researchers provided the option of experimental medicine to parents of children who were doomed to die in pain of a rare genetic condition then the parents would feel they had no choice but to take part in trials of the therapy.  That would violate their consent.  Therefore, only people with a non-life-threatening variant of this disease could take part in the dangerous clinical trial.

Monday, December 12, 2016

Yet another reason to be worried about Trump's presidency

Of course, there are really plenty of reasons.  I don't expect that Trump's potential abandonment of the One China Policy to have more than a 1 in 10 chance of leading to war with China but, well, he isn't even in office yet and this is a thing.

Still, as potentially painful and maybe even disastrous as the next four years are going to be I'm worried that a Trump presidency will be even worse (assuming no nuclear annihilation) in the long run.

I've already plugged The Myth of the Rational Voter as my main model of thinking about elections and that makes me really worried about the lessons that people will draw from Trump's victory.  To summarize, politicians running for office have to compromise between promising things that sound nice to people who aren't really paying attention to policy and promising things that will actually make voters happy and thus vote for them again in the next election.

I think that most politician, at some level, don't really want to believe in people voting for Trump.  We all like to believe that we're normal.  That other people think like we do.  That's often a comforting illusion since people are all so very different but it's natural to believe otherwise.  So politicians, who frequently took their jobs because they care about public policy, will often want to assume that voters care just as much about policy as they do.  But of course voters have a great number of important things in their lives which they prioritize above learning about public policy and contentious political issues.  So Trump lying or making absurd promises works much better than politicians want to believe is possible.

So I'm worried that the establishments of both parties will look at Trump and internalize the message that if they want to get one of their own elected to the presidency then they can't let themselves worry about whether they'll be able to fulfill the promises they're making.  There's no way to get a second term if you can't get a first term, after all.

And I'm worried that this is coming after a previous revelation that's hit congresspeople in the gut.  That most voters know who the president is but don't really know who's calling the shots in Congress.  So if Congress causes problems then the president will get blamed for them.  Maybe I'm imagining that one since Obama has such high approval ratings?  I can only hope I'm imagining that and it's just the US primary system that's been causing problems recently in Congress.

Or maybe it's like a comment on Marginal Revolution said and the dynamic is that TV or movie stars will just win due to star power but most of them aren't interested in running.  That's not ideal but it doesn't seem so toxic in the long run so I guess I'll hope that that's what's at play.

Sunday, October 2, 2016

The median voter theorem, or why major parties are relatively similar

When people are looking at our two major parties they're often dissatisfied.  If you're a socialist or a libertarian or a Nazi then in most elections neither of the major candidates will represent your views.  Well, this election we have someone who at least appeals to Nazis and we nearly had a candidate who called himself a socialist even if that wasn't totally accurate.  But this election is a bit weird and usually the people who complain about the major candidates being close to each other have a point.

Thankfully political science has an explanation for this: the median voter theorem.   At this point I was going to give my own in depth explanation of it but I don't think I could possibly do a better job than Chris Hallquist does here.  Please read that link because otherwise the rest of this post might not make too much sense to you.  Or maybe you're already familiar with the theorem, in which case cool.

The one thing I'd like to add to that analysis is that probably the gap between the parties is partially based on the desires of the people within the parties.  Ego and wanting to be in high office is probably a significant motivation for politicians but I'd assume that many have real preferences for certain policies too.  Polling isn't perfect so nobody knows exactly where the median voter really is on an issue.  If your opponent has set their policies exactly at where the median voter is expected to be then if you care about outcomes more than ego than it makes sense to pull in your public policies a little towards what you really want.  If your opponent wins then the same policies win out but there's still a chance that you might win and get a better outcome than that.  Still, polling is pretty good so the gap caused by that factor shouldn't be large.  And I guess that process would tend to favor less honest politicians, as if we needed another explanation for that observation.

Still, I'd assume that most of the divergence between the two parties is due to having to win primaries and needing motivated party members to go around and drum up turnout.

One objection people might raise to this whole 'median voter' business is the role of money in politics.  Well, I already wrote one post on how I think money is the least important part of lobbying.  Also really we're talking about official positions here and I'd expect donations to effect what a candidate does later, not what they say before they get elected.  Also, money doesn't do as much as you might think.

There is a large correlation between which candidate wins an election and which candidate raises the most money but the problem there is that you'd expect a candidate who is more popular to be able to raise more money.  So to isolate the effects of money on a candidates ability to win a race you can look at non-raised money.  That is, mostly, money spent by rich candidates on their own races above what they could raise from donors.  The result I remember, sorry that I can't find the paper, is that for every factor of 2 one candidate outspends the other then the vote count shifts by 1%.

Well I used to look at that and think that 1% isn't very much.  These days and especially this election I'm less sure.  We'd all like to think that every voter considers the issue carefully but of course many are busy or lazy people and haven't paid attention this election so they just pull the lever for D or R based on their sense of what positions a candidate of that party tends to have.  And many just engage in retrospective voting, usually a good thing.  But between those maybe the number of voters up for grabs isn't actually a large amount, and maybe 1% actually is a pretty significant chunk of votes.

Sunday, September 11, 2016

Recent Reading

Sorry for not posting much recently, I'll try to do more.  To ease myself back in here are some quick reviews of a few books I've read recently that don't deserve their own posts, plus some insights I got from them.

Lost Enlightenment: Central Asia's Golden Age from the Arab Conquest to Tamerlane by Starr, S. Frederick was just what the title leads you to expect.  It's about the flowering of philosophy and science in central Asia between 750 AD and 1000 AD.  The number of merchants involved in the silk road trade had always given the region a large educated class and after the Arab conquest in 750 AD better connected the area to the Mediteranian there was a large intellectual flowering involving greats like Ibn-Sina and Biruni.  But as time went on anti-intellectual movements such as Sufism and books like Al-Ghazali's The Incoherence of the Philosophers made science and philosophy less reputable and more dangerous.  When the Mongol's rolled through in the early 1200s the intellectual era had mostly ended.  And the depopulation of what had been some of the greatest cities in the world by the Mongols plus the resulting shift in trade from the Silk Road to the Indian Ocean meant that the region would never return to what it had been.  I suppose my biggest takeaway is to see some historical developments as more contingent.  Maybe if Al-Ghazali had been born in France and Thomas Aquinas had been born in Samarkand history would have turned out differently?  You could even look at the French Cathars as being analogous to the Sufis in ideas though of course their fates were very different.

Washington: A Life by Ron Chernow was also just what it says on the cover.  I'd known many of the elements of his political life but I was interested in the personal and I also needed to brush up a bit on the timeline of the Revolution.  The perpetually indebted side of Washington is certainly something I hadn't considered and the constant suspicion of the Virginia landowners that they were being cheated by their factors in London helps explain some of their enthusiasm for independence.  I was struck by how complicated Washington's feelings about slavery were.  he opposed the system in theory but for most of his life felt too indebted to free his slaves, especially since many were actually the property of his adopted children and he would need to buy their freedom from the estate he was managing but didn't own.  In light of what I knew about attitudes towards slavery before the Civil War I found his public disparagement of it odd but I later read elsewhere that it wasn't until the Turner Rebellion that pro-slavery forces in the South became so ideological.

Nixonland: The Rise of a President and the Fracturing of America by Rick Perlstein covered a lot of things I'd heard of but didn't have a good context for.  The trajectory of race relations in the North and South over the timeframe, events like Kent State and the Checkers speech, and of course how Nixon ended up thinking that Watergate could possibly be a good idea.   Reading about George McGovern's campaign made me want to become a politician even less.  The people who answered a question in a debate with "I don't know" or "yes, that would be a disadvantage to my proposal" always ended up losing and the people who were willing to confidently make up facts never seemed to suffer for it.  Which of course seems very relevant to our current campaign.   Mostly on the Trump side but you also have bits of disinformation like Trump asking the Russians to hack Hillary's email that get propagated on the democratic side as well.

Sunday, June 26, 2016

The Bad and Good about the Brexit

Britain recently voted to leave the EU.  That's probably going to have a lot of long term consequences and I'm mostly writing this to try to work through what I think they might be, good as well as bad.

In the short term there's probably going to be a fair amount of bad.  Germany and France are Britain's #1 and #3 trading partners and there's likely to be some disruption there.  Now that Britain has said it wants to leave it can negotiate a divorce from the EU there's some question about exactly what Britain's terms of trade are going to end up looking like.  The leave campaign promised that Britain would be able to trade with Europe the same way it always had but now without cumbersome EU rules.  I don't think it'll work that way.  The first reason for that is that managing trade is a big part of the complex EU rules Britain had to deal with.  If I sell you a ton of "Grade A Beef" it's important that we both have the same understanding of what Grade A Beef is.  I mean, I could always just inspect every purchase I make ahead of time but that's cumbersome and so people generally make regulations about what "Grade A Beef" means, exactly.  The modern world of trade is a whole elaborate edifice of commodity futures contracts and such that make that sort of inspection even more impractical.  So Norway, in order to trade with the EU inside the EEA, has to abide by a lot of EU rules it had no hand in making.  So some people in the Leave camp are going to be upset at how little will change regarding EU rules but given that many Leavers are fans of staying in the EEA and given how many people wanted to stay then I assume it's sellable.

The other short term problem is going to be EU stability.  If Britain leaves then suddenly it gets a lot more thinkable for, say, Greece to leave.  That probably means that the EU doesn't want to be nice to the UK in the exit negotiations, they want to make leaving seem scary to any member states that might be wavering.  But in thinking about the consequences of the Brexit for Britain we shouldn't ignore the consequences for the rest of Europe either.  As Scott Sumner points out the stock markets in continental Europe and especially southern Europe are down a lot more than in Britain.  In some ways Britain leaving the EU now looks like Britain leaving the gold standard in 1931, and we all know how that ended.  Partially that might be because the Bank of England has been handling the recent crisis so much better than the European Central Bank.

Finally, I'm a big fan of the free movement of people between countries and Britain leaving the EU is going to be a big blow to that.  I don't think there's much to elaborate on here.  Discomfort with immigration was a big factor in Leave winning and getting out of the EU will put a big hamper on, e.g., Poles moving to the UK.

As for the good, well, I think critics of the EU as an opaque institution have a point.  The EU is the product of ad hoc growth with a lack of clear lines of responsibility.  Hamilton wrote very movingly about the importance of checks and balances separation of powers but since the 18th century countries with more streamlined parliamentary systems have provided much more stable democracies than presidential systems like ours.  Making responsibility transparent to voters is the most crucial thing to get right in a democratic system of government and it's hard to see how the EU accomplishes that.  There was a proposal for a European constitution at one point but it was also quite baroque and also rejected by voters.

In a related point, countries work better when their citizens feel like they're all the same group.  This is entirely subjective and in the future maybe the EU will succeed in creating a sense of a pan European culture.  But in the meantime Germans balk at giving money to Greeks in a way that New Yorkers don't at seeing their money spent on West Virginians.  The book Wars, Guns, and Votes goes into this in some detail and maybe I ought to reread it then write it up.  But in the meantime, this is a fairly big problem for trying to have a union on a European scale.

Also, while I'm all on board with free trade in goods and free movement of people I'm not sure that homogenizing laws across different countries is a good idea.  Lawmaking is not a science and unintended consequences are frequent.  You can take this as an argument against making too many laws but equally it's an argument for trial and error.  More countries with differences in their legal system tend to help us figure out what works and what doesn't - even if we fail to look at other country's experiences too often.

So Britain leaving the EU has large downsides but it has upsides too.  I don't see many people in my social media circles discussing them, though.  But just compare the EU with the TPP and TPIP.  Both are international agreements negotiated between governments to facilitate trade but also impose restrictions on what the member countries can do.

A lot of the motivation for the leave vote was driven by xenophobia and a lot of the motivation for the stay vote was driven by cosmopolitanism.  I am strongly in favor of being cosmopolitan but I don't think people's motivations for doing something have the power to make that thing good or bad all on their own.  So I think that it's pretty clear that from the perspective of five years from now the leave vote will look like a bad idea.  But from the perspective of 50 years I really have no idea.