Over the last few posts I have discussed the many dangers in space that threaten our star mission – the asteroid belt, comets, meteoroids, meteors, meteorites, space dust and debris etc. We also have to protect our astronauts from solar radiation from our sun as we travel away from it and from our new star as we approach it.
To protect our spaceship we need to be certain of detecting and deflecting anything that is on our trajectory or to make adjustments to our course to avoid larger objects that could smash through our defences.
At the relatively low speeds through the solar system at the start of our mission we are less vulnerable. But when we accelerate to half the speed of light we will need advanced detection and a highly sophisticated deflection system – a variable force field. Not just to deflect objects flying through space but also to defend ourselves against the unknown aggressor. We have to generate a low level barrier or field around our starship and be able to rack this up to a directional defensive shield against a major threat.
Detection – Detecting large objects on a potential collision course with our spaceship will be, relatively, more easy to achieve. We already have sophisticated Earth based telescopes and spaced based satellites eg Hubble that can detect objects hundreds of light years away. We also have equipment looking out for asteroids that could come near Earth and recently one did pass between us and the Moon but we had been tracking this since February 2012. However we must not be complacent as we were taken completely by surprise by the Chelyabinsk meteor in Russia and that object was 20 metres wide and weighed 10,000 tonnes!
However by the end of this century we will have developed systems to detect dangerous objects hundreds of millions of kilometres ahead of our trajectory with incredible precision. We will have to because when we are travelling at half light speed [approx 150,000 kilometres per second] an object 14 million kilometres away will be reached in 100 seconds [and quicker than that if it is moving towards the spaceship].
Force Field – The best example to explain the concept of a force field is our planet. Earth is mankind’s spaceship and we are hurtling through space at 100,000 kilometres per hour as we travel around the sun.
And space is a dangerous place as I have described over the last few posts with billions of objects on collision course with us. If we also add solar radiation to the equation we are being continuously bombarded with lethal rays that would turn our planet’s surface to dust with no life possible. But Earth has two force fields with which to defend itself. Its molten iron core creates a magnetic field which stretches tens of thousands of kilometres into space and this magnetosphere deflects the deadly solar wind around the planet. Earth also has an atmosphere – a shell of gas that burns up most, but not all, of the billions of objects raining down on the ionosphere, the upper region. And this is exactly what we need to protect our spaceship – a low level field to divert the radiation and a more powerful, variable field to deflect potential impacts and for defence against possible alien aggression.
Low level field – Here we must emulate Earth’s magnetosphere and create a similar field around our spaceship. This will be required soon for journeys to Mars could become reality during the next 10 years. Scientists in the past have doubted if a big enough magnet could be carried on a spaceship to produce the necessary field. However recent work at the Rutherford Laboratories, UK indicates that a field extending 30 metres or so around our spacecraft can be generated from a very small magnet. This is because there is an interaction between the solar wind particles and the generated magnetic field which multiplies the shielding effect. The following is an extract explaining this…
‘Because the solar wind is a plasma made up of charged particles, it too carries a magnetic field. When the solar wind’s field meets the rocks’ mini-magnetosphere, the two fields clash, exerting a force on each other. Something has to give. Because the solar wind’s field is created by free-moving particles, it is the one that yields, altering its orientation to minimise conflict with the mini-magnetosphere’s field.
Some parts of the solar wind shift more easily than others. The positively charged protons have nearly 2000 times the mass of the negatively charged electrons, so the latter are much more easily deflected. The electrons stay at the surface of the magnetic bubble, while the positive charges penetrate further in.
This separation of positive and negative charges generates intense electric fields up to a million times stronger than the magnetic fields that created them. Subsequent solar wind particles hit these electric fields and are strongly deflected. The result is a shielding effect far more powerful than the magnetic field alone might be expected to provide.’
This work has been proved in the laboratory but has not as yet been trialled in space. However the results are very encouraging and the British laboratory is in discussions with NASA. The article is reproduced in full in New Scientist.
This shield would protect our astronauts from radiation for short [Mars] and protracted [star] missions and I have no doubt that this or similar technology will become reality within the next decade.
High level shield – now we are in the realms of science fiction eg Star Wars where a powerful, variable field can be generated at the touch of a button or more likely a sophisticated computer assessing the threat and applying the necessary defensive field. But this is where we will need to be by the end of this century if we are to go to the stars in 2150.
It is difficult to imagine a large enough permanent magnet that could achieve this. The technology might be an electro magnet powered by the spaceship’s nuclear reactor. But we have to consider all the complex equipment and computer systems on board that could be fried by a huge magnetic surge – and of course our astronauts!
I consider that the shell of our spaceship could be the electro-magnet with its huge, variable field acting outwards and away from the interior. It would be managed by our artificial intelligence computer as situations would have to be assessed and acted upon in fractions of seconds. See how Zec does it in The Blue People of Cloud Planet.
I would like to hear your views on this.
Let us remind ourselves of the definitions of the many objects flying around in space..
- Comet – a relatively small solar system body comprising ice and debris that orbits the Sun.
- Asteroids – are larger solar system bodies that orbit the Sun. Made of rock and metal, they can also contain organic compounds.
- Meteoroid – a small rock or particle of debris in our solar system.
- Meteor – a meteoroid that burns up as it passes through the Earth’s atmosphere.
- Meteorite – a meteoroid that survives falling through the Earth’s atmosphere.
The origin of meteoroids is thought to be small particles that break off comets and asteroids. They are defined by their size which range from smaller than a grain of sand to objects about 1 metre wide. They are incredibly numerous in our solar system as evidenced by the huge number of impact craters on Mars, the moon and other moons around planets. Here there is little or no atmosphere to break up the meteoroid.
Further evidence is that an astonishing 15,000 tonnes of meteoroids, micrometeoroids and space dust enter Earth’s atmosphere every year.
The composition of meteoroids ranges from fragile, low-density snowball objects to dense nickel-iron rich rocks.
When meteoroids hit our atmosphere they heat up and disintegrate into particles which we know as..
We are all familiar with the term ‘shooting star’ and have witnessed these streaks of light in the night sky. What we are seeing is the break-up particles of a meteoroid glowing as they streak though the atmosphere. Most completely disintegrate before reaching the Earth’s surface.
They can be quite spectacular as a single occurrance and multiple meteor showers. A particularly bright meteor is known as a fireball. The most famous is the Leonids a prolific meteor shower associated with the comet Tempel-Tuttel. This occurs annually in November and showers an estimated 12-13 tonnes of particles across the planet. Fortunately these particles are minute and cause no damage to us or the surface not like…
A meteorite is usually part of a larger asteroid or meteoroid that has survived the passage through the Earth’s atmosphere and impacts the surface relatively intact. They may or may not be associated with an impact crater.
Many examples of meteorites have been found on Earth over hundreds of years. The most recent findings occurred in Russia after one of the most spectacular meteors exploded just above the ground at Chelyabinsk showering a huge area with small meteorites.
The most concerning aspect of this meteor is that it originated from a 20 metre wide asteroid that arrived at Earth completely undetected.
Further evidence that space is a dangerous place and our own solar system contains billions of objects which could prove disastrous for our star mission right at the beginning of our journey.
In this post I will concentrate on asteroids. After planets they represent the largest objects and most numerous in the solar system. They are a real danger to our star mission as we have to travel through them at the start of our journey.
But crucially, we human beings would probably not be here was it not for a piece of rock, 10 km wide, flung out of the asteroid belt 66 million years ago – but more of that later.
So what is an asteroid and where did they come from?
There is still some doubt amongst scientists as to the true origins of asteroids. The simplest explanation is that they were the result of failed planets during the formation of the solar system 6.5 billion years ago. Then through multiple collisions and the influence of the huge gas giant Jupiter, the larger fragments, called planetissimals, shattered into billions of pieces and formed the asteroid belt. Some larger asteroids survived – the largest object is Ceres, a dwarf planet at 950 km diameter, followed by Vesta, Pallas and Hygiea which are all in excess of 400 km.
Asteroids are very rocky structures with irregular shapes. None of them is spherical as they did not have sufficient mass during formation – unlike the major planets. Their composition is not unlike Earth as they contain many similar compounds and elements. Asteroids are made of different minerals and substances and their composition depends on which planet they may have originated from. Many asteroids are the result of larger asteroids hitting planets or each other during the fiery beginnings of the Solar System. The chemical reactions that they have undergone over the millennia also effects their composition. The asteroids that are nearest the Sun are mostly made of carbon while the ones further away are made up of silicate rock. The metallic asteroids are composed of up to 80% iron and 20% a mixture of nickel, iridium, palladium, platinum, gold, and other precious metals. There are those few that are made up of half silicate and half metallic.
The metallic asteroids are of particular interest as they could be a source of precious metals in the future when we can find a way to harvest these objects. [But perhaps something has already been capturing asteroids for their own ends? Quest of the Dicepterons?]
Asteroids have been smashing into one another and other planets and moons since the start of the solar system. You can see the craters on the Moon, other planets and even on asteroids themselves – space can be a very dangerous and violent place. Our planet is covered with impact craters and one of these in the Yucatan Peninsula resulted in us – mankind!
So finally let us talk about an event 66 million years ago which radically changed the direction of evolution on planet Earth. Back then the world was dominated by the dinosaurs who had reigned supreme for 165 million years. They ruled the land, seas and skies and ranged from small chicken sized raptors to monsters such as Tyrannosaurus Rex. They were so successful and aggressive that hardly any other creatures could co-exist with them. A small number of vole-like mammals lived underground, only venturing above ground at night to scavenge for food.
In terms of longevity, the dinosaurs are the most successful species that have inhabited Earth. They lived for 165 million years whereas we have existed in our humanoid form for a mere 200,000 years. BUT – the dinosaurs did not know that something was on a collision course with Earth and even if they did would not have had the technology to do something about it.
Earth was struck by an object 10 km in diameter which formed a crater 180 km wide. The impact threw so much debris into the atmosphere that the sun was blocked out and fires raged over most of the surface of the world. The effect on the dinosaurs was devastating – those that were not immediately wiped out by the impact lost their food source and warmth of their star. The extinction of the dinosaurs had begun and few survived – some of the sea dwelling creatures and birds lived through this calamitous time and their descendents, eg crocodiles and alligators, are with us now.
But out of disaster came opportunity. The small vole-like mammals were safe in their burrows and ultimately were able to venture above ground as there were no predators left to attack them. They grew, evolved and spread across a new Earth and 64 million years later humanoid forms stood on two legs in the cradle of Africa. These migrated to every corner of the world and became ….. us. Certainly the most technically advanced species to occupy planet Earth. But will we outlive the dinosaurs? I doubt it – but what do you think?
The weight of scientific argument points to an asteroid strike 66 million years ago but there are still some who dispute this and have offered alternate theories. Whatever it was, it changed the history of planet Earth.
But what if it wasn’t an asteroid that wiped out the dinosaurs? Ah, well, you’ll have to wait for Volume 2 of my trilogy to find the answer to that question……..
…… but meanwhile why not catch up on Volume 1 and book your seats on a dangerous one way mission to the stars?
In the last post I discussed traversing the asteroid belt – a minefield of danger for our spaceship right at the start of our star mission. But there are other bodies flying around in space that we have to avoid and there is often confusion as to their true nature.
I’m referring to asteroids, meteoroids, meteors, meteorites and comets and over the next couple of posts I will define these objects and try to explain their origins and composition.
Let us start with some simple definitions …
- Comet – a relatively small solar system body comprising ice and debris that orbits the Sun. When close enough to the Sun they display a visible coma (a fuzzy outline or atmosphere due to solar radiation) and sometimes a tail.
- Asteroid – a solar system body that orbits the Sun. Made of rock and metal, they can also contain organic compounds. Asteroids vary in size from 500-1000 km across to millions which are less than 50 km. They are concentrated in the asteroid belt between Mars and Jupiter.
- Meteoroid – a small rock or particle of debris in our solar system. They range in size from dust to around 10 metres in diameter .
- Meteor – a meteoroid that burns up as it passes through the Earth’s atmosphere is known as a meteor. If you’ve ever looked up at the sky at night and seen a streak of light or ‘shooting star’ what you are actually seeing is a meteor.
- Meteorite – a meteoroid that survives falling through the Earth’s atmosphere and then collides with the Earth’s surface is known as a meteorite.
You can see that asteroids, meteoroids, meteors and meteorites have certain similarities and links and I will leave their detailed description to the next post.
Comets are different and I will focus the rest of this post on them.
A comet is an icy small solar system body which when close to the sun displays a coma – a fuzzy, temporary atmosphere and sometimes a tail. Both effects are due to solar radiation and solar wind on the nucleus of the comet. They range in size from hundreds of metres to tens of kilometres and are made up of aggregations of ice, dust and rocky particles. Their most interesting characteristic is they keep turning up at regular intervals and have been observed for thousands of years.
The most famous comet is Halley’s Comet which is visible from Earth approximately every 75 years – so some of you will see it twice! It last appeared in 1986 and will reappear in 2061. Astronomer Edmond Halley determined the periodicity of this comet in 1705 and it was named after him.
In 1986 Halley’s comet became the first object of its kind to be observed by a close approach of a spacecraft. This confirmed the ‘dirty snowball’ definition of a mixture of volatile ices – water, carbon dioxide and ammonia – mixed with rocky substances. The comet proved to be a more solid, rocky structure than previously predicted.
The origin of comets is still uncertain. They were once thought to have originated outside the solar system, but more recent theories suggest they were formed during the formation of the solar system and are permanent members of it.
Comets are only seen from Earth about once per year but there are more than 4000 known comets and it is estimated that there are a trillion comet-like bodies in the outer solar system.
That’s a huge number of potentially dangerous objects to steer our spaceship through on our mission to the star Seren.
Between the orbits of the planets Mars and Jupiter lies the asteroid belt; a huge region of asteroids and minor planets presenting its own dangers to our star mission.
So not only do we have to set a collision course for Jupiter [previous post] but we have to navigate the equivalent of a solar minefield of objects ranging in size from 400 – 900 km diameter down to billions of dust sized objects. The largest object is Ceres, a dwarf planet at 950 km diameter, followed by Vesta, Pallas and Hygiea which are all in excess of 400 km.
But avoiding these is relatively simple due to their large size. It is the millions of smaller objects that pose the highest danger to our spacecraft. There are estimated to be around 1 million asteroids in the belt of diameter greater than 1 km. There are billions of smaller objects.
Furthermore the asteroid belt is the ‘birthplace’ of the many rogue asteroids which get flung out onto collision courses with other planets in the solar system including Earth.
Some we know about – eg the asteroid that passed between Earth and Moon [last post] and others take us completely by surprise as in Russia recently [last post]. The latter could be disastrous to a spacecraft travelling at 100,000 km/hour so we will have to develop very advanced detection systems by the end of this century to get us safely out of the solar system.
However, the asteroid belt is so thinly distributed that collisions would be highly unlikely. In fact many unmanned spacecraft have passed through it without incident. But it is a very different matter for a manned mission – we would have to be 100% certain of avoiding a collision as we travel 100 million km through the minefield. Further, collisions between asteroids occur frequently within the belt seeding rogue asteroids which could suddenly be on a course to damage our starship and terminate our mission before it leaves the solar system. Or worse, deflect our ship and crew directly into the gas giant Jupiter.
Even when we exit the asteroid belt there are further areas of asteroids called the Greeks, Trojans and Hildas to navigate but these are a much lesser threat to our mission.
So space is a dangerous place to travel through and we haven’t even left our solar system. To get beyond Jupiter is about 1 billion km and our star is 10 light years away – each light year is 10 trillion km so we have to travel 100 trillion km! We’ve barely covered 0.001% of the distance to our star. What else could go wrong?
Let us assume that our artificial intelligence [AI] computer has completed building our starship in Mars orbit in 2150. It is capable of half-light speed and housing a crew of seven astronauts in cryo-hibernation for at least 20 years.
Its journey to a star 10 light years away will be full of dangers but most will occur whilst it is traversing our solar system at relatively low speeds. Space is not as empty as it seems. We have already filled the upper atmosphere of Earth with tens of thousands of pieces of space junk and any one of these could cause disaster to Earth based missions.
Our solar system is crammed with objects, many of which we know about but even we can be taken completely by surprise – witness the events in Russia recently when a small meteor exploded above ground. In February an asteroid the size of an Olympic swimming pool passed between Earth and the Moon’s orbit and even inside the thousands of communications satellites in space. But we knew this was coming and that it posed no danger.
So we have to be prepared for every eventuality when we finally leave Mars orbit. But our biggest threat is about to happen. We have to set a collision course for Jupiter! – the largest planet in our solar system.
Jupiter is the fifth planet from the sun and is a gas giant with a mass two and half times the mass of all the other planets in the solar system combined. It is nearly 320 times the mass of Earth and that is why our starship is hurtling towards it a velocity of 100,000 km/hour [estimate of future capability].
But Jupiter’s orbital velocity is about 50,000 km/hour and it is charging directly towards our starship – the combined relative velocity is 150,000 km/hour. But this is deliberate as we are about to perform a common manoeuvre in space called the slingshot. We’ve been doing this since the early 70’s eg the Voyager missions and it is done to accelerate and redirect our craft onto its desired trajectory in space.
In essence we use the huge gravitational force of Jupiter to capture our spaceship and send it around the planet and sling it in the opposite direction of travel. In so doing its velocity increases significantly according to a simple equation [Wikipedia]. Our starship would double its velocity to 200,000 km/hour but we are going to fire advanced rockets at a critical point as we pass around Jupiter and this will accelerate us to 1 million km/hour.
It sounds simple but there are huge dangers if we miscalculate our speed and trajectory as we approach Jupiter – get it fractionally out and we will bounce off the gravitational field of the planet onto the wrong course or worse we will be dragged inexorably towards the surface of Jupiter. Further the timing of the firing of the rockets is equally critical to achieving the optimum boost to the slingshot. Finally we must remember that our starship will weigh about 200,000 tonnes. That’s an awful lot of momentum if we get anything wrong.
And, of course, a crew of astronauts who will be totally reliant on the AI computer systems getting everything perfectly right as we swing around Jupiter in the first critical stage of accelerating towards half-light speed. But this slingshot is only the first of the dangers – more in the next post.
Meanwhile perhaps you would like to join the crew of Lifeseeker-1 as she is flung around Jupiter in 2150 at the start of a 20 year journey to the star Seren.