For the upcoming inferior conjunction of Venus and Earth, there is a growing community of amateurs that are bound and determined to get a communications signal bounced off Venus and received here on Earth. This is EVE. The inferior conjunction is when Venus and Earth are the closest together.* This is the right time to attempt this feat, and it happens only once every 18 months or so.
The channel is daunting. So, ORI, SBMS, and others, have put together a link analysis.
Everything can be found at https://github.com/OpenResearchInstitute/EVE
This includes the current link analysis Jupyter Notebook, and all the support files to make it run, and more. Such as, all the documents used to propose observing sessions at the “really big” dishes at Green Bank and Effelsberg.
What can we do now to help make good things happen?
We have a modulation and coding scheme designed especially for this channel.
But we need to test it BEFORE Venus whooshes by in October of 2026. We need to test it now. We’ve tested in simulation, sure, but we all know that’s not good enough.
We need to test it with the Moon. EME is a close enough channel. It doesn’t have the same Doppler spread that Venus has, because the Moon is “locked” to the Earth, but it does wiggle around a bit, and it is a very hard microwave channel.
Want to help? Have you been waiting for a reason to build an EME station? Wait no more.
What do you need to do? Build a station capable of EME. Be able to send an arbitrary digital waveform (IQ modulation from SigMF files) and be able to receive it. We need a lot of data here.
EME stations are so fun. We want 1299.5 MHz (1296 MHz will do) and 2304 MHz. I’m building a 2304 MHz station.
What will happen if we’re successful? We dramatically improve our chances to do the first ever communications over EVE. We’ve been able to bounce a carrier wave (radar return) off of Venus twice. Once in 2009 and once in 2025. Let’s move things forward.
The communications protocol itself is of interest as well. It’s not just a low SNR type of deal. The Doppler spread, from the rotation of Venus, is kind of a drag. This exact type of thing, bouncing a signal off a rotating surface, is some of the most difficult things to deal with in digital communications. For Venus, the left side of the planet is moving away from us. The right side of the planet is moving towards us. We illuminate the entire planet, so our signal is warped when it bounces back to us.
We can deal with this. This is something that digital communications folks generally avoid, because it wrecks the signal. But, we have a solution. Let’s try it with EME and find out if we’re right.
Are you in? Let me know, and welcome aboard.
* The inferior conjunction is when Venus and Earth are aligned with respect to the Sun, when Venus and Earth are on the same side of the Sun. The superior conjunction is when the Earth, Venus, and the Sun are all in a line, and Venus and Earth are on opposite sides of the Sun. Because of elliptical orbits, Venus and Earth are actually not the closest together at the inferior conjunction! Being closest together is what we want, for radio. The actual closest approach is within three days of the inferior conjunction. All of this is documented in the proposals and link analysis. What comes out of looking at this data, is that we have several weeks of very good opportunities, and not just a short window. Multiple bites at the Venus Apple, while it’s near us, have every chance of succeeding.