May 25, 2012

Beyond the Heliosheath: ISM Traverse & The Local Fluff

Posted by in categories: engineering, futurism, space

It’s been a while since anyone contributed a post on space exploration here on the Lifeboat blogs, so I thought I’d contribute a few thoughts on the subject of potential hazards to interstellar travel in the future — if indeed humanity ever attempts to explore that far in space.

It is only recently that the Voyager probes provided us with some idea of the nature of the boundary of our solar system with what is commonly referred to as the local fluff, The Local Interstellar Cloud, through which we have been travelling for the past 100,000 years or so, and which we will continue to travel through for another 10,000 or 20,000 years yet. The cloud has a temperate of about 6000°C — albeit very tenuous.

We are protected by the effects of the local fluff by the solar wind and the sun’s magnetic field, the front between the two just beyond the termination shock where the solar wind slows to subsonic velocities. Here, in the heliosheath, the solar wind becomes turbulent by its interaction with the interstellar medium, and keeping the interstellar medium at bay from the inners of the solar system, the region currently under study by the Voyager 1 and Voyager 2 space probes. It has been hypothesised that there may be a hydrogen wall further out between the bow shock and the heliopause composed of ISM interacting with the edge of the heliosphere, another obstacle to consider with interstellar travel.

The short end of the stick is that what many consider ‘open space’ to traverse once we get beyond the Kuiper belt may in fact be many more mission-threatening obstacles to traverse to reach beyond our solar system. Opinions welcome. I am not an expert on this.


Comments — comments are now closed.

  1. Great article, thank you. Most people, such as me, can only imagine how wonderful it is–space exploration and the future in space. Good article.

  2. x says:

    Thank you for sharing.
    This is exciting news!

    So many mysteries still abound right here in our own “little” solar system.. and on the edge of it!

  3. Ray Wright says:

    Some decades ago, it was claimed that travel above the atmosphere would be impossible due to the extreme temperature of th ionosphere. That was confusing temperature with heat. Some people actually thought that spacecraft attempting to leave the Earth would flash into vapour. The solar wind does protect us from high energy particles from deep space, and so does our atmosphere, but a few feet of rock would do that too. So if we ever get around to building space arks for humans to venture into interstallar space, they will need protection, but that coud be done by mining an asteroid for the rock, and laying it down between an inner and outer hull. We need not feel so pessimistic that we are trapped within the solar system. We are not trapped in that way, but what worries me is that the global economy will become so strained in the decades to come that the ability to build anything in space will disappear, so the time to develop re-usable transport to space is now — or never.

  4. flashgordon says:

    Cosmic rays with the heliosheath pose problems; the question is does the Heliosheath stop any cosmic rays; i doubt it.

    The heliosheath is more about photons than solar storms(electrons and protons). The Stars might look brighter out past our own Heliosheath(I remember a recent astronomy article about the advantages of astronomical seeing out past the Heliosheath; they’re that detailed folks!) But, that’s not like sunburn levels.

    To say the least, I don’t see the Heliosheath as some Ptolemaic crystal sphere that would hurt to go through!

  5. Sylvana says:

    Nice propositional argument post! You know that I am been a open that our scientists can still discover new knowledge out in our solar system.

  6. Tom Kerwick says:

    Ray — not a bad analogy to the ionosphere — and I was not suggesting an entrapment — just potential hazards that provide engineering challenges.

    Flash — I don’t think it was suggested that the heliosheath stops cosmic rays — or agree that it is more about photons (??) — as stated above is more about where the protons and electrons of the solar wind reach a termination shock where these slow to subsonic velocities and result in a buildup of turbulence and also an increase in density in the mainly hydrogen atoms of the local fluff which it is pushing against.

    My use of the phrase ‘hydrogen wall’ may have misled a little in the above: Think of it as an afront of two mediums pushing against each other — a skin of higher density material and high turbulence would manifest where they interact. This slowing to sub-sonic velocities refers more to typical solar wind particles of up to 10 KeV of course. One would expect the higher energy cosmic rays to shoot through largely unaffected.

  7. Could one of you eminent astonomers/philosofers give an answer to this point on the NASA Voyager link?

    ‘The first feature encountered by a spacecraft as a result of this interstellar wind/solar wind interaction was be the termination shock where the solar wind slows from supersonic to subsonic speed’

    Space, being a virtual vacuum (where nobody can hear you scream) sound therefore doesn’t really exist. What therefore is the correct measured velocity at which sound travels in interstellar space ?

  8. Eiko says:

    Yes, it’s an old argument to many of us. Other hand, it’s just aeohtnr statement in a long debate. I think there’s a kind of social argument going about whether manned space flight makes any sort of sense in the long range, comparable in some ways to the long argument about whether slavery was morally acceptable.I.e., matters of fact are of less signifiance to the participants than their emotional states; and the debate will likely be decided by force majure (e.g., a Civil War) than by logical agreement. Some people like the idea of humans spreading into the cosmos; others find the notion pointless or even repellent. This isn’t going to be resolved for all time by a handful of (mostly) American citizens arguing in the year 2010.Not to say this is an argument for ceasing to argue