Sunday, 1 April 2018

Should All Interstellar Missions Be Silent?

The first detected interstellar object passed through the inner Solar-System last year, and is now heading away back to interstellar space. Named 'Oumuamua', the object, approximately 230 metres in length and around 30 metres wide, reached a speed of almost 88 kilometres per second at its closest approach to the sun.

Oumuamua: an interstellar object that passed through the inner Solar-System in 2017. It is potentially a camouflaged extraterrestrial embryo colonisation starship making use of our sun for a gravitational course correction.

There's a reasonable possibility that the object is artificial. It could be an interstellar colonisation mission that is using our sun to provide a gravitational  course correction, putting it on its final trajectory for its target star system, or setting itself up for another gravitational course correction in tens of thousand years time. And it could well have made some passive observations of our planet on the way through.

The object is too small to be a generation ship. A ship many times larger would be required to allow thousands of beings the chance to live and breed for many millennia as their voyage unfolds. But the ship is certainly large enough to be what is arguably a more efficient means of interstellar colonisation: an embryo ship. Such a ship would need to be much more advanced, requiring artificial wombs, and artificial 'parents' and educators. If Oumuamua is indeed such a vessel then it would be a remarkably complex technological marvel, and something worth pursuing when we have the means to do so.

On board an embryo star-ship a human colonisation crew is grown in artificial wombs

A lot of effort was made to detect signals from Oumuamua. None were detected. But why should any have been? Such an interstellar ship, with embryos only, would be fully automated, with no sentient crew (apart from perhaps an overseeing artificial intelligence). There would be little reason for the ship to make a transmission home, except during the safe interstellar phases of its voyage. Even if it did, it would be a very directed and focused transmission that would not hit our planet. And using stars such as our sun to provide course alterations would almost eliminate the need to use a means of propulsion, the emissions of which would be detectable, while transiting the system.

Maintaining a strict 'silent running' policy is essential for all pioneering interstellar missions. Only very targeted and rare encrypted transmissions to the home world should be made, and only when the ship is well away from possibly inhabited star systems. The rest of the time a starship should appear, apart from during the very closest of inspections, as a natural object. Any course corrections using a propulsion mechanism must only be made in interstellar space.

This seems to be the most sensible approach for us when we finally embark on colonisation missions to other star systems. And I would expect it's the approach taken by extraterrestrial civilisations that are already undertaking such voyages. That would certainly explain why we are not detecting any transmissions. Such strict controls are obviously being maintained during voyages, and when colonies are established. And such controls are no doubt being enforced on home worlds.

It's very likely that, at this point in time, our civilisation is one of the very few (even the only one) in our region of the galaxy allowing unregulated transmissions without considering how visible we are to civilisations in the surrounding star systems.

Listening for signals from extraterrestrial civilisations is a good idea. But is it wise to also transmit messages in the hope that one of them receives it? Perhaps we have not detected any civilisations because they have a good reason to keep quiet. Maybe we should, too...

This could possibly be to our advantage. It could act as a warning that our star system is home to a reckless species that does not care what it does, and who knows about it. It could make potential invaders think again and head for a quieter system.

Or more likely it could act as a sign that we are an undeveloped and ignorant species, unaware of the risks of attracting attention. We could be considered an easy target for eradication, and Earth as an easy project for redevelopment. Or we could simply be 'silenced' to prevent us bringing to this region the malevolence other civilisations fear.

We have only been transmitting radio signals for just over a century. That is not really enough time for any alien civilisation to analyse those signals and complete a voyage here. But there are already many star systems identified within a hundred light-years of our planet that could host life and even advanced civilisations. Our unfettered radio transmissions could have been detected decades ago.

If such a civilisation is advanced enough to already have starships constructed then it may not take much effort or time to prepare and direct one this way.

Extra-terrestrial visitors may well be friendly, but we should also be prepared for a hostile encounter

An interstellar ship or probe could be on its way to us right now. If it's able to reach speeds that are a significant percentage of the speed of light it could arrive by the turn of the century. We need to take seriously the possibility that an extraterrestrial civilisation has found us. 

They may be heading here right now.

It would be wise to prepare for an encounter with them within the lifetimes of those born today. We should hope that they are benevolent, and be ready to greet them as friends.

But we need to plan for the possibility that they are not.

Thursday, 1 March 2018

Comfortable Homes on Mars

Mars is one of the most likely places in the Solar-System where the first permanent human colony away from Earth will be established. With the right equipment the planet has all the resources required to sustain a community indefinitely. And there is also the intriguing possibility of discovering evidence of an ancient technological civilisation that once existed on the planet.

Before the search for such evidence can begin there are practical issues that need to be addressed. Habitats with enough space and comfort are required to maintain the physical and mental health of the colonists. And such space and comfort should be ready and waiting even for the very first colonists to arrive. They will need decent quality homes, with enough comforts to get them through the months and years before they have the opportunity to return to Earth. Those habitats should be nothing less than a home from home.

There are plenty of designs for such habitats, but NASA's ice home concept is one of the more practical and impressive ones.

NASA's Mars ice home. The inside is inflated and then the outer shell filled with water. It can be constructed robotically and be ready when astronauts arrive.

The home consists of an inflatable torus within which there are two levels of living space comparable to that of a small house on Earth. The torus is surrounded by chambers filled with ice to provide insulation and radiation protection. The water for the ice will be extracted from the subsurface ice that is abundant in many locations on Mars. Because of this the actual structure itself is very lightweight and can be deployed and build robotically. The homes would be delivered to Mars and prepared over the span of a year or so. When humans finally arrive they'll be able to move immediately into comfortable habitats.

A cross-section of NASA's ice home showing the interior space

Whatever the design of the house, its interior should offer the ocupants the comforts of a home on Earth. It should be a familiar and safe place to return to, with space to relax and have privacy when required.

The first humans visiting Mars will almost certainly face a stay of at least a couple of months, and possibly a year or two.  And that would be after many months of arduous travel in a cramped spacecraft. It is vital that those humans are provided with all the normal comforts possible to allow them to recover physically and mentally: essential for them to do their work effectively, and also for them to prepare for their return journey.


The interior of a house on Mars should offer all the comforts of a home on Earth. It should be spacious, clean, bright, and be familiar and cosy.

Such homes should last many years, and be ideal for the early missions. But ultimately they would be temporary. One day people will arrive on Mars who will never leave. And soon after that the first children will be born there. By that time a substantial and permanent habitat will need to have been constructed.


Space X Mars surface colony circa 2050 with a busy spaceport. Large numbers of human are arriving as the construction of permanent habitats continues. Many of those arriving at this time will never leave, and many will start families there.

The best place for permanent homes is below ground, or inside hills and mountains. Excavating such facilities from scratch would be an immense undertaking, but utilising existing underground chambers, such as lava tubes, would reduce the workload significantly. Homes for thousands could be build in such tubes, and the thick shielding required by surface habitats would not be necessary as the roof of the tube would be more than adequate.

A colony set up in the relative safety of a lava tube on Mars

As well as exploiting natural underground voids such as lava tubes, there is the possibility to exploit unnatural voids, too (see my previous articles 'Sanctuary Entrance Found on Mars' and 'Where Did All the Martians Go?'). The search for such 'unnatural' voids is, in my opinion, one of the two primary reasons for sending humans to Mars (the other being, of course, to aid in the survival of our species if and when a global catastrophe occurs on Earth).

There is strong evidence to suggest that Mars was once a temperate world: one that could have been a perfect environment for life to thrive. That environment was likely to have existed for more than a billion years. That's more than enough time for an advanced civilisation to develop. For whatever reason that life-nourishing environment began to fail. It could not be saved. If there was a Martian civilisation it would have had no choice but to retreat underground (with a privileged few managing leaving the planet). 

Eventually the underground civilisation would have died out.

Colonists on Mars explore the remains of a long dead underground Martian city

Many of the vast chambers and warrens of tunnels they constructed must still remain, ready to be exploited when our civilisation arrives on the planet. There may be huge networks of structures and dwellings that could be modified for human habitation. Within just two centuries there could be a population of millions of humans living on Mars with complete independence from Earth.

When the first humans arrive on Mars and have their first colony up and running they must begin the search for those underground chambers. And from where better to embark on that search each day than a safe, spacious and pleasant home with all the familiar comforts of Earth.


Thursday, 1 February 2018

Secret Colonies Beween the Stars

We tend to think of human colonies beyond Earth as being located on planets or moons around stars. The abundant energy resources at such locations certainly make such thinking logical and sensible.

But such locations are also the most visible and desirable. And that makes those locations the most likely places where we may encounter a competing and hostile civilisation.

While we should certainly colonise other star systems, we should also consider colonising deep interstellar space. We should create clandestine colonies; ones that limit contact with the star-bound colonies. Those clandestine colonies would need to be large and self-sustaining, and most importantly  they would need to be 'silent', with no emissions, including light, detectable from even just a single light-year away.

A clandestine interstellar habitat under construction. A rogue asteroid is used to provide the resources required.

Such colonies would be our insurance. They would passively monitor the surrounding human colonies, watching and listening for signs of distress. They would ensure our continuation as a species should our star system colonies suffer natural or unnatural catastrophes.

In an earlier article titled 'Living on Rogue Planets' I explored how life could evolve on planets between the stars, how humans could colonise them and reasons why such planets would be safe from various threats. But finding such worlds would be difficult, and they would be unlikely to be in the right locations. It would be better to create our own rogue worlds in exactly the locations we want, and where they would not drift close to star-systems for millions of years.

Simply put, the clandestine colonies must be located in the right places to be able to remain hidden essentially forever.

But how could such remote colonies be created and sustained?

One possibility would be to create generation starships that would intentionally 'stop' in the void between stars. Such spacecraft would,  of course, need to have very efficient and self-sustaining ecosystems and the means to provide appropriate energy generation. This could be fusion-based, or even antimatter-based. This would provide enough energy to create the light and warmth for growing food to maintain a significant human colony.

Resources would be required for manufacturing replacement parts, new equipment and topping up air and water supplies. Comets from the very outer reaches of star systems (such as the Oort Cloud in our Solar-System) could be redirected to pass close enough to the clandestine colonies to be easily mined.

A comet in the Oort Cloud is moved closer to the clandestine human colony nearby. It's resources will help sustain and grow the colony for centuries or more.

Such redirection would be relatively easy as objects in the Oort Cloud are very loosely bound to the sun due to their vast distance. Those objects are essentially just a nudge away from being truely interstellar.

Of course, the Oort Cloud itself is about one to three light-years from the sun, which puts it in interstellar space. This would enable some interstellar colonies to remain shrouded in darkness and secrecy while having access to a sparse but relatively abundant set of resources.

The Oort Cloud in relation to the rest of the Solar-System and its closest neighbouring star-systems. It would be an ideal location for secret human colonies, with relatively easy to find resources from the mass of comets in that interstellar region.

If such clouds of objects are common around most stars it would make setting up such colonies much easier. It should be an essential component of any interstellar colonisation missions that humans embark upon.

Creating sustainable colonies between the stars will be a formidable task, but it is a crucial one. Those colonies will be our backup, and the skills learned by those surviving (and hopefully flourishing) there will be invaluable as the human species spreads throughout the galaxy and beyond.

Monday, 1 January 2018

Time Travel: Travelling Without Moving


One thing that seems to be almost completely overlooked when time travel is discussed, or used within a work of fiction, is location (the only example I can find that mentions it is this Dilbert cartoon strip).

This is a critical omission.

If someone was to go backwards or forwards in time just one minute they would not find themselves standing in the same place on Earth in relation to their original surroundings. They would most likely find themselves many kilometres up in the air, or embedded in rock deep underground. This is because the Earth is rotating and moving through space at many thousands of kilometres per hour as it orbits the sun, which is also moving in relation to the center of our galaxy, and so on.

The classic image of a time machine: something a person could sit in, type in a date, and then travel to that time at that particular location on the surface of the Earth. But the problem with this concept is that the Earth would not be in that location at the destination time period.

To put it simply, we are constantly moving, and so travelling in time will mean we travel to a time before the Earth was in its current location, or to a time after it has moved on. If someone travels in time just a few days they will find themselves millions of miles from Earth in deep space. If they time-travel a couple of decades they will find themselves far beyond the Solar-System in interstellar space.

Time travellers waiting to enter the machine that will send them through time. If such a machine was possible the travelers would need to be on board a spacecraft as they are likely to emerge in deep space. This is a point never considered in fiction.

But the issue of location should not be viewed as a problem. Far from it, in fact. It should be viewed as a major advantage. If we can eventually master time travel in some form it could well be the easiest and fastest way to travel interstellar distances, if only along the path the Earth will take, or has taken.

It's an incredible prospect. But can it ever be possible?

Travel into the future can be achieved, in principle, using the time dilation effect described in Einstein's theory of relativity by travelling close to the speed of light. Travelling to the past would require velocities that exceed the speed of light. This is theoretically possible using cosmic strings, wormholes, or an Alcubierre drive. A huge amount of energy would be required, which would need exotic matter, particularly matter with negative mass. It's all very complicated, and not well understood. But our understanding will improve in this area, as it always does. Sometime over the next few centuries the generation and control of such vast amounts of energy may well be harnessed, and then a device that would enable time travel could be constructed.

Assuming such a device could be built, perhaps in the form of a large orbiting facility that could transport large spacecraft across time, what would be the best way to use it?

An orbiting time portal, capable of transporting large spacecraft to other times

Sending a human crew through such a portal would be an immense undertaking.

Such an expedition would essentially be a one way trip to an unknown destination, with no possibility of return or help once the journey had begun. The spacecraft would need to be interstellar in nature, with the ability to sustain its crew and passengers for decades if necessary, as there would be no way of knowing how close a viable planet would be at the time of arrival. At best we could target the vicinity of an appropriately aged star system that we think has a good chance of hosting an Earth-like planet. And due to the impossibility of knowing the conditions of any planet found for colonisation, the ship would need to contain all the resources required to land and set up a colony in a variety of climate conditions.

However successful the mission is, no one left on Earth is likely to ever know about what happened.

If we just want to ensure the continuation of Earth life we could simply send thousands of probes to different times along the Earth's journey path and have them 'seed' the most Earth-like planets they find with the building blocks of Earth life. One day, a billion years later, perhaps a technologically advanced species would evolve on some of those worlds, an incredibly distant relative of our species.

A probe, sent through time to seed suitable planets with Earth life, arrives and begins observations

I use term 'simply' in a relative sense as this kind mission would still be difficult and complex. The probe's would have to be smart, with artificial intelligence beyond what is currently possible. They would need to observe and detect the most suitable planets or moons within their range, plot and execute a suitable trajectory, and despatch their payloads without any help from scientists on Earth.

Perhaps there are civilisations out there right now based on Earth life, evolved from simple life forms sent back through time by our descendants. If we do eventually master time travel then perhaps we go on to seed worlds a billion or more years ago, when other galaxies occupied our location. Perhaps a bipedal species, reptilian, mammalian or avian (or something extraordinarily different), will one day build a time portal to send explorers to our galaxy.

Perhaps they will find Earth and the ultimate origin of their species.

Or perhaps they will seed Earth and be the origin of ours.