4 Pi SETI - Why Not Build the Argus Radio Telescope Full Scale?

Robert Dixon

Update: we need to digest this first. All-sky there could be 2000 FRBs per day.

This  post - like nearly all the others - is about the questions I have. I am not a radio astronomer.I want to know how and how much and when about the radio telescope we will discuss below. This was stimulated by my interview with Robert Dixon last year, in which he discussed the virtues of the Argus concept. I lay awake that night thinking about it, and wondering why it hadn't been built yet.
 
The Search for Extraterrestrial Intelligence (aka SETI) is just that - a search. Like any search, it becomes much more difficult when more dimensions are added to the search space, and far easier when one or more of those dimensions are removed.

For example, if you are looking for an obscure little store with the best barbeque ribs in the West, and all you know is that it's in Los Angeles County, then your search space is quite large. However, if you have the additional information that it's on Santa Monica Boulevard, then you you still have some searching to do, but much, much less. You might even find the joint before it closes.

The problem with the SETI search is that it uses telescopes, and telescopes like the Allen Telescope Array or the Arecibo Observatory, only look at a small part of the sky at any one time. In fact, all the radio observatories in the world put together are only looking at a tiny sliver of the sky. If an ET beacon is transmitted for a short time while you are looking at another part of the sky (which you almost certainly are), you would completely miss it. We can dream about adding more telescopes to the search, but we would need a ridiculous number to cover the whole sky at once - or would we?

Questions about Asteroid Mining

What follows is based closely upon the Wow! Signal Podcast's Burst 8.

Lately, it’s been my sense that it’s time to spin up the asteroid mining conversation in earnest. Our most recent Unseen Podcast episode (#33) covered asteroid mining, and space policy expert James Muncy joined us for the first part of the show. We received a comment on the blog post for this episode by “Khani”, and here it is verbatim:

Question - (case 1) I travel to an asteroid of 100 meters in size. I start extracting materials from the "equatorial" zone. Is the material mine? (case 2) is the asteroid mine? (case 3) I move the asteroid, and now someone else lands on the other side and starts harvesting it. Is that "illegal" ? How much does the asteroid to be moved to be claimable? One meter?

Respectable test cases, I think, but we can go further.

Co-bloggers sought

I have plans to revive this blog, but I am asking for help. If you like writing about science, space, the human future, SETI, astrobiology, or related topics, then I'd be interested in either a merger or just taking you on here as a co-blogger. If, after reading a bit through this blog, you are interested in this, post a link to a couple of things you've written, and tell me a little about yourself. Gender, nationality, and age are not important.  You need access to a computer and a facility with written English, and that is all.

Whither this Blog?

I clearly have not found enough time for this blog. Between work, family, hobbies, moving house, and three podcasts, it has been allowed to lapse. Part of it is that I have been saying much of what I want to say on the Wow! Signal, or as part of Unidentified Science. However, I can see just a little blue sky ahead, and hope to slowly ramp up the post rate over the next year or two. Part of it will be finding a synergy with the Wow! Signal, and part of it is getting the workflow streamlined on the Unseen Podcast, so that it doesn't need so much care and feeding.

It's not that there's nothing more to write about. New ideas and results are emerging all the time, and I'll be happy to move this blog forward.

Want to help? Engage with me. There is a comments section below every post. You can also follow me on Twitter  (@PaulDCarr) and on Google Plus, and I would encourage you to join the Unseen Podcast panel pool.  Right now, people who want to appear are able to get on the show about half the time.

The Long Delay Echoes

The subject here is a scientific mystery that was well documented by European scientists in the 1920s and 1930s, well before any man made objects were launched into outer space, and then was largely forgotten. The phenomenon has since apparently disappeared, although anecdotal reports still pop up from time to time, and a low level of interest persists. We are discussing it here, because although no one knows for sure what caused the Long Delay Echoes, one plausible explanation is Bracewell Probes. The Long Delay Echoes (LDEs) just possibly might be a clue to how to find such a probe.

Some Basic Background You may Wish to Skip

 I'm sure you know that radio waves generally travel at the speed of light, and can be bounced off of various surfaces and also off the Earth's ionosphere if the radio wavelength is long enough. The speed of radio waves can be a bit slower if they are traveling through a medium such as a plasma or water, but generally the speed is not much less than the 300,000 kilometers per second we are used to. That means, if we send a radio signal out, and see it come back to us, then to calculate the distance to the reflector, we divide the time delay in seconds by 2 (since it went out and back), and then multiply by 300,000 kilometers per second to get the distance. Then, if we send out a radio signal and it comes back 2 seconds later, it must have traveled 300,000 km each way, or most of the way to the Moon. Amateur radio operators often enjoy bouncing their signals off the moon, which generally exhibits a very weak echo delayed about 2 and one half seconds. Strong echoes, or echoes delayed longer than 2.5 seconds, are not moon echoes.

Since the 1960s, there are many radio repeaters in Geosynchronous orbit, but the round trip delay is much shorter than the moon -  less than half a second, and you generally won't see a satellite echo at all unless your signal parameters are just right - and probably illegal.