TRAPPIST 1

I’m pretty sure you’ve heard by now of the latest big discovery, that being four new exoplanets orbiting TRAPPIST 1, a star in the constellation of Aquarius. Aquarius is visible on the Northern Hemisphere, but TRAPPIST 1 cannot be seen with the naked eye.

TRAPPIST 1 is an ultra-cool dwarf star, at least 500 million years in age. That is a minimum age estimate, and in reality the star could be several billion years old. At about 8% Solar mass and 11% Solar radius, TRAPPIST 1 is likely to live much longer than our Sun.

TRAPPIST 1 is about 39,5 light years away. With our current methods it is of course unreachable, but I’m thinking this would be a strong candidate for my story. Three of the planets are within habitable zone, and assuming the have any sort of atmosphere they may also have water.

I suck at math, but from a few calculations I did last night (and probably botched), a generation ship could cover the distance in less than ten generations with even 50% light-speed. Now, for the sake of fiction that might be plausible.

So, the planets. Three planets were found already back in 2015, but now the team had more data and found four more planets. Even more new data will become available early this coming March (to the public on the 6th). This new data is by the Kepler telescope and spans over 70 days of observation. It might give new insight as to whether there are even more planets on orbit, what the planet masses are for the currently discovered planets and the orbital period of 1h. Also, Kepler takes observations on the overall brightness of TRAPPIST 1.

So, the three most interesting are the ones in the habitable zone, called 1e, f and g. 1e is about 0,7 Earth masses, f the smallest at about 0,6 and g the largest at 1,1. G gets about as much light from TRAPPIST 1 as the zone between Mars and the asteroid belt get from the Sun, f about as much as Mars. 1e is the most Earth-like, as it gets about as much light.

Even more new information can be discovered after the launch of the James Webb Space Telescope, scheduled to launch 2018. JWST is accurate enough to give readings on the gas composition of the planets’ atmospheres and the presence of water or other gases usually resulting from life (I say usually, because oxygen and ozone can also be created by chemical reactions or the star’s unusually high UV radiation). Among these gases are oxygen, ozone and methane. These readings will be available in about five years.

As TRAPPIST 1 is rather small, the planets are quite close together. This causes the planets to have gravitational impact with each other, which could also cause consequences on planet surface. The strength of the impact is dependent on the strength of the planets’ possible atmospheres. The positive side of this effect is that it allows the planets’ masses to be more carefully measured than otherwise.

The other negative effect are the solar flares. TRAPPIST 1 has flare occurrences weekly and bigger flares bi-annually. Unless the planets have magnetic fields they cannot resist the radiation and will most likely be uninhabitable.

SETI is observing TRAPPIST 1, but so far nothing has been received. It’s also been pointed out that due to the extreme distance the signal would most likely be static anyway.

Apart from these news I also discovered a couple interesting points I need to explore further in my story. I’ve been trying to figure out how I could make a generation ship work – how medical care skills, engineering skills and so on can be passed on as the first Earth-trained generation ages and dies away.

That’s the main issue: spare parts can be stocked up and the amount of fuel must be system-regulated and present at takeoff. The engines and other systems must be kept in operating condition through the journey, though, and the passengers must arrive in acceptable health and numbers to settle.

I have some solutions thought out, but I doubt none of the first-level solutions will be manageable all the way through. We’ll see.

So long for now, the Sun is shining and I’m going to enjoy that while it lasts.

 

 

 

 

HD164595 Signal

Some of you have certainly already read the news of the strong signal received last year (and only just now reported to the general public) from 94 light years away. Finnish media put up a few articles of space and signals and how unlikely it was that intelligent life was anywhere.

The signal was picked up by an international team of researchers with a RATAN-600 telescope in the Russian Caucasus. The source appears to be at or near a star named HD164595 in the constellation of Hercules.

The star is 0,99 solar masses and approximately 6,3 billion years old. The metal structure and temperature are also rather similar to our Sun.

HD164595 is orbited by at least one planet. It is thought to be a warm Neptune type planet of 0,05 Jupiter mass with an orbital period of forty days. Obviously this planet is too close and likely too warm to support life (unless we start thinking SciFi). Other planets in the system have neither been confirmed or ruled out.

If it was the work of an advanced civilization, they would have to have advanced to at least I or II on the Kardashev Scale. As we know, human civilization is still at 0. There is nothing yet to merit such claims – and the scientists behind the find are the first to remind us so. They encourage more study of the star in question in hopes of a repeated observation.

It has also been brought to general knowledge that the frequency of the transmission is the same as is used by military transmissions and that there might be military satellites in orbit that SETI scientists do not know about that might cause such interference. (Seriously though, are military satellites really that much more important than the possibility of intelligent life in space? Make peace, not war!)

I truly do hope that more research is pointed that way. As some have said, this is one of the strongest SETI candidates in long time, and as such further study is definitely merited. If only to disprove the chance and to free the resources to other uses.

94 light years is a long time, on the other hand. It might be that if the signal was intentional the civilization that produced it exists no more. Who knows what kind of natural disasters are possible on faraway planets, not even taking into accord other dystopian possibilities.

Definitely something I’ll be keeping an eye on.

Space and health

Here’s a subject I feel is necessary to tackle early on. Obviously if my entire crew gets killed before reaching their destination, there’s not much story to tell. And when I started researching the subject I realized I might have actually overlooked some rather critical issues by glossing it over.

Most of the study on effects of spaceflight on human body is of course concentrated around weightlessness. Since all the numerous health issues it causes I think it’s rather obvious my ship will have some sort of artificial gravity.

Just in case you want to know though, weightlessness causes at least the following issues:

  • muscle athropy
  • skeletal deterioration
  • slowing of the cardiovascular system
  • decreased red blood cell production
  • balance disorders
  • eyesight disorders
  • weakening of the immune system
  • fluid redistribution
  • loss of body mass
  • nasal congestion
  • sleep disturbance
  • excess flatulence

Now that we’ve covered that, let’s move on.The problems likelier to arise during my written voyage are as follows:

  1. Radiation. Radiation causes the immune system to weaken and causes chromosomal aberrations in lymphocytes. The viruses we are already resistant to on Earth might cause us and the rest of the crew to get sick again in space. And obviously, large doses of radiation could cause cancer.
  2. Psychological effects. Being cramped into a large but limited space with a LOT of people from different cultures can and will be stressful. You have to cope with these people because you cannot get away from them. Also, anxiety, insomnia and depression may become issues partly due to above and the fact you’ve left everything you know behind. The latter three are more likely to truoble the first generation more than their descendants.

There are also some interesting little tidbits I found during my research:

Apparently, a very very short duration exposed to the void of space will not kill you instantly if you are reintroduced to normal pressure in a way similar to how deep sea divers are treated. Depending on the methods available this could be rather risky in it’s own accord and I bet it won’t feel that nice either.

You won’t also freeze to death instantaneously because your body heat will radiate away rather slowly.Prolonged stay is really not recommended in either case as there is nothing to breathe out there.

Anyway, in conclusion I must state the following obvious fact. No matter what solutions one comes up with in terms of radiation, the ship must have one heck of a medical center. There needs to be equipment for practically everything from giving birth to dental care to surgery. Also, I’m thinking the medical staff will need to be numerous.

I was going to go further in detail about psychological issues, but most of the articles I found focused on the effects of sleep deprivation  productivity. To me at least it’s no surprise that not sleeping makes you a bad worker. Decided to skip that part until I find articles of more relevance.

Possible Targets Pt.2

I just realized I never actually followed up with this. Let’s fix that right now, shall we?

Gliese 581

  • 20 light years away
  • has 3 confirmed planet
    • possibly 3 more
    • at least one of the planets is too hot to sustain life
    • one confirmed to be in the habitable zone
  • red dwarf star
  • has a comet belt surrounding the system at ˜25-60 astronomical units

Gliese 667

  • 23,6 light years away
  • 3-star system
    • A and B orbit each other in 42,15 years, C orbits the pair at a distance of 230 astronomical units
    • A has 73% of the Sun’s mass, 76% radius and 12-13% luminosity
    • B has 69% mass and 5% luminosity
    • C is a red dwarf with 31% mass, 42% radius and 1,4% luminosity
  • C has at least 2 planets
    • one of these may have liquid water and is warmer than Earth

Vega

  • 25 light years away
  • blue-tinged
  • 455 million years old
  • 400% of the Sun’s luminosity, twice the mass
  • fast rotation makes the star wider in the middle
  • surrounded by a debris disk spanning 70-100 to 330 astronomical units (may reach as far as 815 AU)
  • may have a planet or planets larger than Jupiter on orbit
    • may also have a planet the size of Neptune and smaller planets closer to the star

Small fun fact: can be seen during the summer in the Northern hemisphere, where it will shine brighter than the last star of Ursa Minor’s tail, roughly opposite to said star.

Gliese 876

  • red dwarf star
  • 32% mass and 1,24% luminosity of the Sun
  • at least 4 planets in orbit
    • two of those may be about the size of Jupiter
    • two are in the habitable zone, 0,116-0,227 AU
  • depending upon theory thought to be either 6,5-6,9 billion years or 0,1-5 billion years old

 

Orbital Mechanics

Is basically the application of ballistics and celestial mechanics (separate post coming later) to practical problems, such as the motion of rockets or other spacecraft. Newton’s laws of motion and universal gravitation are used in calculation of these problems.

Main focus of orbital mechanics is spacecraft trajectories. There’s plenty of mathematical formulae for different situations, but for these purposes I’m just going to skip the maths (I’m really bad at math, so I’d just screw things up if I tried). You can find them online if you want to know. The practical applications of all the math are mostly orbital maneuvers, orbit plane changes and interplanetary transfers.

If two spacecraft want to dock in orbit the trailing craft cannot just fire its engines to go faster (because the trajectory will change). Multiple precisely calculated engine firings in multiple orbital periods may be required (may take anything from hours to days).

Basic transfer orbit is ellipticalAlso other options available (bi-elliptical, general).

There are a few basic points I’m going to put up here just so I have them on hand, as follows:

  • Kepler’s laws of planetary motion (abridged)
    • orbits are elliptical with the heavier body always at the center (think of the Earth and Moon) – circles are also a special case of ellipse!
    • the square of a satellite’s orbital period is proportional to the cube of it’s average distance from the planet (or sun or whatever one’s orbiting)
  • without applying force the period and shape of the satellite’s orbit won’t change
  • a satellite in a low orbit moves faster than one further out
  • if thrust is applied at only one pointin the satellite’s orbit it will return to that same point on each subsequent orbit, though the rest of it path will change
  • from a circular orbit, a thrust applied in a direction opposite to the satellite’s motion changes the orbit to an ellipse
    • it will then reach its lowest orbital point at 180 degrees away from the firing point
    • if thrust is applied towards the direction of motion, highest point is 180 degrees away

Nifty pictures may be edited in on a later date. No promises.

Possible targets pt. 1

I’ve yet a few more promising star systems to research, but let’s split the post in two. So, without further ado…

Alpha Centauri

  • 4,37 light years away
  • three star system, Alpha Centauri A and B and Proxima Centauri
    • Alpha Centauri A has 110% mass and 151,9% luminosity of the Sun, yellow in color
    • B has 90,7% mass and 44,5% luminosity, orange in color
    • Proxima Centauri is a red dwarf
  • Slightly older than the Sun, 4,5-7 billion years
  • planets:
    • Alpha Centauri B has one planet, 20,4 day orbit time; too close for life. Possibility of other planets in the habitable zone (0,5-0,9 AU)

Barnard’s Star

  • 6 light years away
  • low-mass red dwarf
  • 7-12 billion years old
  • 0,14 solar mass, 15-20% of the Sun’s radius
  • planets in the habitable zone would be very close to the star and suffer from solar flares etc.

Sirius

  • 6 light years away
  • consists of Sirius A and B
    • A is about twice the size of the Sun
    • B is a white dwarf
  • 2-300 million years old
  • orbit each other in 50,1 years
  • no confirmed planets

Epsilon Eridani

  • 10,5 light years away
  • at least one giant planet in orbit, 2 asteroid belts. May have another planet within a dust belt
  • 82% of the Sun’s mass, 74% of the Sun’s radius, 34% luminosity
  • presence of a large planet at a close proximity to the star makes finding a planet in the habitable zone (0,5-1,4 AU) unlikely

Tau Ceti

  • 78% of the Sun’s mass, 79,5% radius, 55% luminosity
  • planets:
    • possibly five in orbit, all larger than Earth
    • orbit periods 14-640 days
    • two of those in the habitable zone
    • debris risk about ten times greater than in our solar system, makes life unlikely in the system

Propulsion

So, a few words on my propulsion research.

I don’t really think this is everything possible said on the subject, likely I’m only glancing at the tip of the iceberg. However, I really doubt I should ever go into too much detail on mechanics and mathematics behind the actual function of whatever propulsion method I choose to use (the really nitpicky technical details are something I quite often just glace through when reading Sci-Fi) ’cause not that many people would understand them or appreciate them.

You know, all that stuff is just a bit heavy on the brain. And I’m sure not just my brain. Boring people to death with technical details is not really what I’m after with this story, although I think I should drop the occasional line about the matter that would actually be true and/or plausible.

So, on to the possible means of moving through space!

Nuclear fission

Ion engine

With this engine, electric power is used to create charged particles of the fuel. The fuel used would usually be Xenon. The charged particles are then accelerated to extremely high velocities.

It’s a rather low force solution, but possible speed is only limited by the power available. What would be used to supply that power is bit of a mystery to me at this point.

The down-side of this solution is that it’s only suitable for interplanetary travel. Perhaps it is suitable for use in some of the smaller spacecraft used after human race has conquered far away systems. Not to be used in my interstellar (intergalactic?) ship.

Fission-electric

This is a very long-lasting engine type at low thrust.

However, it is limited to deep-space operations as it would not be able to leave atmosphere. It would stay in-orbit and landing to planetary surface should be done with smaller, higher-thrust vessels.

Also, it’s not suitable for interstellar travel.

Fission-fragment

Creates high-speed jets of nuclear fragment ejected at about 12000 km/s. In order to reach maximum velocity the reaction mass should consist of fission products.

This type uses a lot of fuel and therefore isn’t all that cost-effective for any long journey (the fuel I assume would take quite some room).

Nuclear pulse

Driven forward by series of nuclear explosions.With fusion-antimatter catalyst this one could reach 10% of the speed of light. If instead a pure matter-antimatter annihilation rockets were used, this could theoretically achieve 50-80% of the speed of light.

The problem with this system would be slowing down: either about 50% of the fuel would need to be saved for slowing down or alternate solutions need to be used. For this purpose, a magnetic sail has been proposed.

Project Daedalus from 1970s took the idea a bit further. The plan was to use externally triggered inertial confinement fusion. What this means is that fusion explosions are produces via compressing fusion fuel pellets with electron beams. Also laser, ion beams, neutral particle beams and hyperkinetic projectiles have been suggested in place of electron beams.

Nuclear fusion rockets

Can reach up to 10% of the speed of light. With enough fusion stages could reach close to the speed of light.

Antimatter rockets

If energy resources and efficient production methods to make antimatter in quantities needed are found and the antimatter could be stored safely, this propulsion method could theoretically reach speeds of several tens of percents of that of light.

So, the problem really is that 1) we don’t have the energy resources to make enough antimatter, 2) we can’t do it efficiently currently even if we had the energy and 3) we don’t know how to store it.

Then there’s the fact that at the annihilation of antimatter quite a bit of energy is lost to gamma radiation and neutrinos. Just because of the radiation some sort of shielding methods would be needed to protect passengers and cargo.

As far as I gather this would still be a better choice (if we forget the radiation) as about 40% of mc² would be available. With nuclear fusion it’s only 1%. If the loss of fuel to radiation and neutrinos could be prevented the number could be higher.

Speculated methods

Just a list. Might revise to expand on these later.

  • quark matter
  • Hawking radiation rockets
  • faster-than-light travel
  • Alcubierre drive

So, there are quite a few choices. I can’t lie and say I’d understand much of what I’ve read on the matter and therefore decided to focus on the parts I’m actually sure I got (or think I understood, whichever is closer).

Should have paid more attention in my physiscs classes…