Thursday, March 31, 2005
Energy – Earth, Moon and Man
It’s a worthwhile pursuit to
ponder the various energies of Earth, Moon and Sun.
Earth mass 5.9737E+24
Moon mass 7.34767E+22
mass sum 6.04718E+24
Gravity constant 6.67259E-11
Earth-Moon radius 384400000
angular velocity 2.66531E-06
dr/dt = 1.21048E-09
L12 momentum 2.85862E+34 kg.m^2.s^-1
E12 energy 3.80955E+28 J
dL/dt = 4.50092E+16
Earth radius = 6378137 m
Earth I = 8.01889E+37 kg.m^2
Earth w = 7.29212E-05 rad/s
Le = 5.84747E+33 kg.m^2.s^-1
Ee = 2.13202E+29 J
(notice more energy is packed into Earth’s rotation on its own
axis than in the Earth-Moon mutual motion)
dw/dt = (dL/dt)/Ie
= -5.6129E-22 rad/s
dEe/dt = 3.28213E+12 W
The above is the energy calculations for the Earth-Moon system. Earth slows
by ~ 0.002 seconds a day every Century, and this releases 3.3 terawatts as
frictional energy in the oceans.
What if humans got all their energy from the tides?
Energy consumption = 10000 W/person (in USA or Australia)
population = 6300000000
total 63 terawatt.year => compare current (= 15 TW.yr)
terawatt-year = 3.15576E+19 Joules
natural depletion time = 4.73364E+20 seconds
= 2058410434 years (2 billion years)
(actually it’s an asymptotic approach to zero. Thus in about ~ 15 billion years the Earth/Moon will be synchronous with ~ 1/2000 th of its current energy)
@ 63 TW.yr, t = 107237508.4 (100 million years)
@ 2.6% growth, t = 570.803779 years
Amazing what exponential growth can do.
Of course only a tiny fraction could ever be used per year, but with enough tide machines we might tap ~ 100 TW.yr/yr, slowing Earth down in a mere ~ 66 million years. The synchronous radius is at 553757 km, and the length of day/month will be the synchronous
period 47.176 days.
Famed early 20th Century biologist J.B.S.Haldane once predicted fictionally that the desire for central heating would cause the tides to be excessively tapped and the Moon to spiral out then reverse and break-up into a ring, bombarding the Earth – in about 3,000,000 AD.
So what does our mere present day 15 TWyr mean in terms of barrels of oil?
# oil barrel energy = 6100000000 Joules
# million barrels/annum = 77,600.65574 (call it 80 billion barrels)
# daily = 212.4590164
As for carbon dioxide produced here’s some relative figures…
# coal 32800000 J/kg 3.666666667 kg (CO2 per kg fuel
burnt) 8945455 J/kg CO2
# oil 44880000 J/kg 3.087719298 kg
14535000 J/kg CO2
# wood/biomass 16400000 J/kg 1.833333333 kg
8945455 J/kg CO2
5% energy non-carbon fuels (nukes, hydro, wind, solar)
total carbon-fuel energy… 1.425E+13 J/s
# coal = 0.5 7.125E+12 J/s 796493.9024 kg(CO2)/s
# oil = 0.4 5.7E+12 J/s 392156.8627 kg(CO2)/s
# biomass = 0.1 1.425E+12 J/s 159298.7805 kg(CO2)/s
total (tons) = 42538052582 (42.5 billion tons)
(at present only about 3 billion tons/annum stays in the air – the rest is taken up by the oceans and plant-life. However we may hit the limit of that natural regulation before too long – last year’s uptake was lower than previous years, causing fears that the limit has finally been reached)
And how much is in the air already?
# CO2 mass = 380 ppm = 3.92654 kg/m^2,
# thus total = 2.00056E+15 kg (2 trillion
tons) = 47.03 years @ current production levels
At 5% of the atmosphere CO2 is toxic for many people. That’s 6,192 years of
current burning. But how much is there in the ground?
# commercial coal/oil: 9000 TWyr = 8.2 trillion tons of carbon
(mostly coal – oil is rarer)
# all sources : 18,000 TWyr = 16.4 trillion tons carbon
– much is inaccessible commercially by current methods
Hence, at most, CO2 can only rise to ~ 33 times the present value. That’s 1.25% so there is no danger of toxicity, but plenty of trouble from the greenhouse effect if we burn it all.
time to depletion:
@ current levels: 600 years & 1200 years respectively
@ 2.6% growth: 246 years & 273 years…
…exponential growth again. Theoretically coal can be used to form hydrogen
and this can be used in fuel cells @ 50-70% efficiency (x 2 current levels),
which buys just an extra 27 years in both cases. That’s the doubling time at just 2.6% growth.
Conclusion: in just 300 years all fossil fuels will be gone. CO2 will be ~
12,500 ppm, unless we sequester it as carbonates and/or liquefied CO2 under
high-pressure on the ocean floors. Alternatively if someone can find a way of making stable solid carbon dioxide (called “carba” – analogous to solid SiO2, silica) then all problems will be solved.
Another handy unit of energy is the “megaton of TNT” which is exactly 10^15
gram-calories, a gram calorie being the energy needed to raise the
temperature of a gram of water by one degree Celsius. According to
relativity one kilogram of rest mass is equivalent to m.c^2 in energy, and
since c is 299,792,458 m/s that’s almost 90,000 trillion joules per
kilogram, or exactly 21.47 megatons of TNT.
Some catastrophes for comparison…
# Boiling an ocean takes ~ 2.7 megajoules/kg and there’s 1.4E+21 kg of ocean.
That’s 3.78 E+27 Joules = 900 billion megatons.
# To melt the Earth’s average 17 km of crust (= 17,000*3,000 kg/m^2 = 51E+7
kg/m^2) means raising the rock by ~ 1100 degrees @ 500 J/kg. That’s 550,000
J* 51 million kg per sq. metre = 1.43 E+28 J = 3.4 trillion megatons TNT.
# Finally to disrupt the Earth utterly requires sending its entire mass past
its own escape velocity. For a uniform density sphere that’s E =
3/5.G.M^2/R, or 2.24E+32 J for the Earth – just a bit more than x1000 its
rotational energy. It’s roughly 50,000 TRILLION megatons TNT, or 1 trillion
tons of antimatter explosive placed at the Earth’s core… quite a trick.
# In Greg Bear’s “The Forge of God” some aliens drop two chunks of neutronium on
opposite orbits inside the Earth – one matter, the other antimatter.
Neutronium is 100 billion times denser than water and flies through solid
rock like it was rarefied air. Eventually the two chunks meet and detonate
Some advocate detonating Venus because it has such a rotten atmosphere, but the energy disparity…
# removing the atmosphere @ 10^6 kg/sq.m, needs 54 MJ/kg, 4.6 x 10^14 sq.m… total = 2.5 x 10^28 J
# disrupting Venus ~ M^2/R = (0.815)^2/0.95 (in Earth units) = 0.7 Earth disruption energy = 1.57 x 10^32 J
# Ratio: disruption/removal = 6300 times…
thus removal is far, far cheaper energy-wise. If we import hydrogen from Uranus to make carbon and water out of the CO2 and the energy needed is even lower. By the end of that process Venus will have a 4 bar nitrogen/helium atmosphere and about a kilometre equivalent of water in its lowlands, most of which will soak away into the parched soil. Shallow salty seas and the high pressure will mean water vapour will be diluted and unlikely to escape to space like it did when Venus first dried up. The highlands should be pleasant.
Earth’s orbital energy around the Sun is 2.65 E+33 J, or some ~ 12 times
higher than its disruption energy. Stopped in its tracks, say by a counter-rotating planet, and the Earth would fly apart as a cloud of hot gas at 30 km/s. This isn’t so crazy
a scenario. According to Michael Woolfson, a planetary physics professor in
the UK, Earth and Venus were once cores of two gas planets that collided.
The resulting blast was hot enough (> 5,000,000 K) to cause nuclear
reactions in the planets’ gases and form odd isotopes of otherwise common
elements. The collisional debris heavily eroded one of the planets’ moons
almost stripping it to its iron core – that moon is now Mercury. Another
moon became Mars, while another Mars-sized moon smashed into Earth to form
the Moon – it’s iron core sank into the Earth to join our core.
Posted at 8:47 am by Adam
Make a comment Permalink
Friday, December 03, 2004
Open church… no way
When we need every bit of tolerance in this day and age the big US TV stations take a flying leap backward with this one, refusing a Church advert that shows maybe gay couples barred from going in. Come on! JC said forgiveness was open to everyone and never said gays were wrong, wicked or evil. Yet it’s too controversial a topic for a Church ad – which wasn’t even in your face explicit about it – in a time of Presidential opprobrium.
The Church in question is an interesting American invention which we don’t have here in Oz, the Zion United Church of Christ, which has an interesting congregation here, because their Reverend apparently went to Hell, which would seem to be a strong bit of evidence in the Church’s favour.
His vision was particularly interesting as he was coming out of Hell into the angelic realms as he didn’t have an anthropomorphic vision but saw them as “balls of light”, one manifestation of the Faerie and UFOs. This implies a common “Other World” to my mind, which has an overlying “glamour” for the inexperienced. What Rev. Storm saw was that World in its real form, as you’d expect from the Angels of the Light.
So will it make me a Believer too? I’ve fought long and hard to be an agnostic, so I want a bit more validation before I give in. The Other World is prone to taking the form our thoughts cast upon it – Storm is interesting because he was an “atheist” with no distorting expectations. Another web-page of interest covers the post-life rescues of Ben Swett.
Posted at 12:56 pm by Adam
Make a comment Permalink
Outer Solar System origins…
In the Sun’s birth nebula the odds of a stellar near miss were much higher, leading to the perturbing of the proto-Kuiper Belt, as described by Kenyon and Bromley’s latest simulations and at Scott’s webpage.
I think that would make for an interesting mix of planetoids out there, some from the Sun and some from the other star, with a ratio of 5:1 apparently. Sedna might even be one from the other star.
Alternatively, following Woolfson’s Capture Theory, the Jovians all collapsed out of protostar filaments produced by the early Sun passing within ~ 1000 AU of diffuse protostar or a collapsed protostar with a disk. This would have a much higher probability and explain the Sun’s slow rotation, the inclination between the Sun’s rotational plane and the Ecliptic and a lot else that traditional cosmogony has trouble with.
Posted at 12:38 pm by Adam
Make a comment Permalink
Thursday, October 28, 2004
Homo floresiensis… Hobbit Man
Who said palaeoanthropology had no surprises left? Along comes the incredible findings from the Indonesian island of Flores – Hobbit Man. The type specimen – a woman – is just a metre tall and sports a mere 380 cc of brain-power. That’s chimp-size and smaller even than Australopithecus [typically 400-450 cc], but this hominid left behind tools and not just bashed stomes like chimps, nor sharp flakes like Homo habilis, but hafted mini-blades and the like.
BBC news-links are permanent, whereas newspaper stories get archived quick and cost to view, so I will leave it at that. Look just about everywhere and you’ll see Homo floresiensis in the news.
National Geographic on Hobbit Man
What it means for evolution is cryptic – first a small brain didn’t mean a species was stupid. Hence a lot of guess-work about behaviour will need a review. Second it means that humans are mammals and on small islands they can evolve minature forms just like other mammals – elephants on Flores did it too, but examples exist all around the world. Mini-hippos, mini-elk, mini-mammoths, other minis all of varieties.
So we are mammals first. Let that sink in. Then ask yourself, “how differently should we see our Great Ape kin?” More later.
As far as palaeoanthropology goes the tiny Homo habilis seemingly associated with tool finds – like ER1813 [510 cc skull] and OH62 [showed a small stature] – aren’t so odd. A recent find of a jaw intermediate between ER1813 and ER1470 [usually called Homo rudolfensis, about human size] suggests to me a movement from mini-human, perhaps recently off an island environ, to full-sized.
Here’s that find, OH 65, at National Geographic and some links to ER1813 and ER1470. OH 65 has its own web-page, but OH 62, the “Dik Dik Hominid” doesn’t have a web-page to itself, but can be found in summary here.
If a human existed as brainy as a chimp shouldn’t we give chimps a human-level respect? On the one hand I agree. Chimps, gorillas and orang-utans are our nearest kin, perhaps even “human” in a pre-linguistic way. They deserve full human rights. And full protection. No more hunting, no more experiments. NOW. Time is running out for all of them as habitat is being destroyed and they’re being actively poached by trinket makers and bush-meat murderers.
OTOH chimps, gorillas and orangs aren’t like us in important ways. They have no discernible abstract language, no apparent durable culture, and probably no abstract social structures like contracts, marriage, rights. These things are meaningless to them. How do we then bridge that gap and include them in humanity without destroying them? And since the new finds of Homo floresiensis are so recent – a mere 18,000 years – these little people might still exist in forest refugia the question is even more pertinent: How do we include them and help keep them from the worst of our uniquely human mistakes?
Final point. A new species of ape has been possibly found in Africa. According to the few good witnesses – credible primatologists, not untrained locals – they mix gorilla and chimp features. If they are fertile hybrids then that has two important consequences – that chimps and gorillas are sub-species… and we are too. Ponder that. Genetically in all respects chimps and humans are equally far apart from gorillas, yet if chimps and gorillas can hybridise, we can too. We are then sub-species of one species – not genera apart, but actual blood relatives. No longer genera Gorilla, Pan and Homo, but just semi-species of some larger group.
Every death of an ape in Africa is MURDER. Every death of a chimp in a Western lab is MURDER. Think about that.
Posted at 2:10 pm by Adam
Make a comment Permalink
Thursday, October 21, 2004
Ocean Planets and Minor Bodies…
Ocean planets are COLD planets. As odd as that might seem if an Outer planet has a warm atmosphere and a large size then it gets too hot deep down for water to remain liquid. It becomes a super-fluid – hot but very dense because of the pressure – or even high-pressure ice, usually ice-VII. No liquid. Here’s an abstract… Ocean Planets …which teasingly leaves the existence of an ocean on Neptune an open question.
Another interesting astronomical excursion is the Kuiper-Belt and the Oort Cloud – is there something messing up the orbits of the “iceteroids”? John Matese is one astronomer asking just that question. His homepage has a lot of juicy papers available if you’re curious. He’s one of the astronomers who caused a stir by suggesting evidence was available in perturbed comet orbits for a brown-dwarf companion to the Sun.
Final piece… Robonauts on Wheels… RoboSegway…which is kind of relevant in that it means that teleoperated machines are just that much closer to practical applications. I’d like to see them used to service Solar Power Satellites which seems like a better option than vaguely proposing them as exploration devices. The reaction time-lag across interplanetary distances is much too large for any teleoperation, but GEO’n’back is a mere 0.2 seconds away for radio. Much easier.
However how long until corporate types see this as a means of out-sourcing hands-on technical services???
Posted at 1:25 pm by Adam
Make a comment Permalink
Science & Tech News
White Knight to carry X-37…White Knight
Pioneer Effect: a recent news bite…Guardian: Pioneer Mystery
Methane made in the Mantle…Methane in the Mantle
Acoustic Power Converter for Deep Space…Travelling Wave Generator
Thermoelectric power recovery from exhaust heat…Diesel Energy 1 kW recovery
No More Alternators
High Z thermoelectric
Japanese Intro to Thermoelectrics
Hi-Z Thermoelectrics you can buy
Magnetic Beam Riders to Mars… Mars’n’Back in 90 days
BBC Coverage of Mag-Beam
The last one is the most interesting. The Mag-Beam is the Diet version of a Neutral-Particle Beam interstellar launcher, which is one option for getting to nearby stars [Look for the "Interstellar Transportation" download]. Under-power it by several orders of magnitude and you get a Mag-Beam.
Posted at 12:55 pm by Adam
Make a comment Permalink
Cornucopia of Space Ideas
One thing about the space business is the sheer volume of paper studies of “good ideas” and the fact so few ever become real-life space-probes and such like.
Here are two concepts to illustrate that. First is an aero-captured Neptune Orbiter which is set to reach Neptune in less than 12 years and boosted on its way via Solar Electric Propulsion [like Deep Space 1] plus some planetary snooker with Jupiter or Saturn.
A beefier version is the Nuclear Electric Neptune Orbiter which will be akin to the planned JIMO orbiter. Such a system will have more grunt than its tamer cousin but more of the technology is untried, especially power from a proper reactor rather than an RTG.
Personally I think as thermoacoustic power generators mated with RTGs mature they will compete very effectively with reactor-based systems. But reactors don’t degrade in power over time like RTGs so they have that one advantage.
Both proposals have a long arduous road ahead before becoming real space-probes. Consider Gravity-Probe B – 40 years it has been in the planning, hoping and building stages. Or Galileo which had been on the books since the 1970s, finally launching in 1989 and arriving in 1995, recently retired to a suicide plunge into Jupiter’s clouds. That’s 30 years from “go” to “whoah”.
Poor Gravity-Probe B has possibly been scooped too. The general-relativistic frame-dragging it was meant to measure has been detected by a couple of Geodesics satellites. At least GPB will get to refine the measurements…
Other Wild space ideas are available from several aerospace companies here in links from a SpaceRef article. A variety of architectures for George Bush’s new Space Vision are proposed – some are rehashed from countless paper studies done by the veterans, while others are genuine innovations and updated revivals of good, bypassed ideas. Check out tSpace’s work for some innovation [WARNING: BIG PDF]
Posted at 12:42 pm by Adam
Make a comment Permalink
Friday, October 15, 2004
Burt Rutan’s Space Ship One has achieved what so few others have managed to do – a manned sub-orbital rocket flight. Only a couple of Mercury launches did that. Next step is LEO, and there is a new “X-Prize” being put together to tempt adventurous types into trying for it. A good concept is something like the Gemini spacecraft from the 1960s. Details [from Encyclopedia Astronautica ]…
# Unit Cost $: 13.00 million.
# Crew Size: 2.
# Typical orbit: 246 km circular orbit, 30.2 deg inclination.
# Length: 5.67 m.
# Maximum Diameter: 3.05 m.
# Habitable Volume: 2.55 m3.
# Mass: 3,851 kg.
# RCS Impulse: 119,103.00 kgf-sec.
# Main Engine Thrust: 72 kgf.
# Main Engine Propellants: N2O4/MMH.
# Main Engine Propellants: 455 kg.
# Main Engine Isp: 273 sec.
# Spacecraft delta v: 98 m/s.
# Electrical System: Fuel Cells.
# Electric System: 2.16 average kW.
# Electric System: 151.0 kWh.
# Associated Launch Vehicle: Titan 2, Titan 3C.
SpaceX’s Falcon V could launch a neoGemini easily. Its estimated payload to LEO is 6,020 kg once the new Merlin 2 engines are operational. And for a price of ~ $20 million it’s worthwhile since the Orbital “X-Prize” will be a cool $50 million. Plus the first stage is reuseable cutting costs potentially even more. So will it work?
Posted at 1:46 pm by Adam
Make a comment Permalink
Tuesday, September 28, 2004
More Space News
SMART-I is approaching the Moon – displaying the utter snail’s pace trajectory that ion-drives do so well. Ion-drives are great with some juice behind them, but solar-electric arrays are too heavy to provide very much power to get real performance. Hence probes like Deep Space -1 and SMART-1 and the DAWN mission are really, really slow. Yet they get delta-vees that chemical rockets haven’t got a hope of approaching.
Personally I think we’ll see much better ion-drive performance from advanced RTG powered probes like the Pluto Orbiter Probe I posted links for a week ago. Very advanced conversion systems using Stirling Engines will get ~ 30% efficiency and allow ion-drive power of +10 kW jet-power. With a 10,000 second Isp that’s about ~ 0.2 N thrust – doesn’t sound like much, but sustained for years it can take a ~ 1000 kg probe anywhere.
A really excellent picture from the Mars Odyssey is this view from orbit of a Mars Exploration Rover (Opportunity, I think) as it is skirting Bonneville Crater. Yes, we really do have two amazing little robots strolling around the Red Planet, and they will keep transmitting back to us for another six months at least.
Seeing all the interesting rockets and dust and sand, do we really want to send people there? To live? I do. And I’d love to go. It’s a whole planet waiting for the touch of Life, Life that will liberate its cousins from a few fragile oases when we melt the ice-caps and thicken the atmosphere. Paul Davies has written a very interesting probability analysis that indicates terrestrial Life is more likely to have originated on Mars than on Earth. Hence by colonising Mars we are reclaiming our Home.
Posted at 12:19 pm by Adam
Make a comment Permalink
The way ahead into near-space seems to be the multiple commercial efforts that are attempting to build suborbital rockets – chiefly Scaled Composites SpaceShipOne effort, but they’re not alone. Richard Branson, always an aerospace enthusiast, has gotten behind Scaled with this news release revealling his plans…
Which is eeriely predicted (though for orbital flights) in Buzz Aldrin’s 1997 book “Encounter With Tiber” – guess Branson has been hanging out for viable technology to arise. More details of the plan are reported by the BBC here…
Virgin Galactic Next Steps
Virgin are not the only ones talking about orbital stations operated as private businesses – Bigelow Aerospace is putting real money into building the first such orbital habitats, as reported here…
Bigelow Orbital Prize
…and they’re putting up a $50 million prize for an orbital vehicle capable of servicing the habitats. That’s serious money for anyone who thinks they can build a ship capable of getting there and back. For even launching it on a currently available booster. Like this plan…
SRBs as CEV Launcher
…and if you didn’t follow the link the SRBs are Solid Rocket Boosters like the Shuttle’s, but man-rated by adding an orbital booster stage to bring down the gee-forces and increase the payload. The CEV is the Apollo-style capsule proposed for the USA’s new space exploration venture, but such a vehicle – BUT cheaper – is perfect for Bigelow’s Big Prize too.
Posted at 11:42 am by Adam
Make a comment Permalink