Tag Archives: NASA

The Voyager twins: weak signals and discovery from the depths of space

Artist’s concept of Voyager I (Source: NASA)

Yesterday, while listening to the BBC World Service, I heard this fascinating documentary focusing on the Voyager I and II spacecraft. It absolutely blows my mind that both of these spacecraft have been operating for 40 years and continue to send signals back to Earth. Talk about weak signal DX!

Note that you will have to visit the BBC World Service website to listen to the documentary via their media player.

(Source: BBC World Service)

Voyager 1 and 2: Still operating after 40 years in the depths of space. Voyager 1 is currently some 20 billion kilometres from Earth travelling at 15.5 kilometres a second. It takes 19 hours for a signal from the spacecraft’s 20 watt transmitter to reach home. Voyager 2 is 17 billion kilometres away and will soon leave the Solar System.

Launched in 1977, the twin spacecrafts have explored the giant planets and their strange moons, investigated the boundary of the Solar System and changed how we see our place in the Universe. The probes even carry a message for aliens in the form of a golden record.

Retired NASA astronaut Ron Garan meets many of the original team still working on the mission, nursing the twin spacecraft through their final years.

Click here to listen to the documentary via the BBC World Service website.

NASA’s ionospheric experiment tonight and remembering The Woodpecker Project

The gas mixtures from NASA’s ionospheric experiment cause parts of the night sky to glow blue and green. (Photo: NASA)

Many thanks to SWLing Post contributor, Ed, who writes:

It might be interesting if you invited SWLing Post readers today see how NASA’s ionospheric experiment tonight (shortly after 9:00PM ET) affects RF propagation along the east coast:


I searched online to find any reference to this long series of NASA experiments affecting RF propagation, and found this 1980 paper:


…which contains this paragraph:

Ionospheric Modifications

The objectives motivating various experiments based on either decreasing or increasing the ambient plasma density by means of a chemical release include: (a) obtaining measurements of the rate of refilling after creation of a plasma depletion “hole” as a means of studying ambient ionization processes, (b) studying the magnetic field aligned propagation of VLF waves by creating a propagation duct, (c) simulating the formation and movement of the natural depletion “bubbles” which occur over the magnetic equator, (d) investigations of reaction rates, recombination coefficients, airglow production, etc., and (e) creating the conditions for inducing selected plasma instabilities to produce ionospheric irregularities and spread-F conditions. The science objectives in these experiments have a direct bearing on communication problems. Other forms of ionospheric modification are directed toward studying ionospheric/magnetospheric coupling and testing plasma theories.

So it might be fun to crowdsource from the SWL community to see if we can detect any propagation anomalies Tuesday night during this brief experiment. It’s unfortunate there’s not more time to coordinate different listeners monitoring different assigned frequencies. This reminds me of participating in ANARC’s “Woodpecker Project” in 1985 with 95 other SWL’s in 18 countries to determine the interference effects on HF broadcast from the Soviet Union’s use of Over-The-Horizon (OTH) radar in the HF bands.

I wonder how many SWL’ing Post readers participated in The Woodpecker Project and still have the nice “No Woodpeckers” tee shirt they earned for submitting their findings, which were combined into a final report that condemned the Soviets for causing interference on the HF bands.

Thanks for the tip, Ed! According to the linked article, the experiment will take place this evening, “soon after nine o’clock eastern time” (or 01:00 UTC).

This would be a great time to do an SDR wideband spectrum recording since you could possibly see any propagation effects on the waterfall display and play the event over multiple times. I’ve no clue if this experiment would yield any discernable results on HF, but it would be fun trying to detect it nonetheless.

Please comment if you plan to check out the experiment and/or if you were a participant in the Woodpecker Project!

George Knudsen (W4GCK): A Life in Apollo


I’m very proud to note that my good friend, George Knudsen (W4GCK), has been featured on the excellent omega tau podcast.

The interview is absolutely fascinating–here’s a description:

George Knudsen started working in 1958 on the Redstone missile, and moved on to working on the Atlas ICBM. Later he worked on the Saturn 5 launch vehicle, where he was responsible for the fuel tanks. He was on the launch team at Cape Canaveral for various Apollo missions. In this episode [we] talk with George about his work in this fascinating period of science and engineering history.

Click here to listen via the omega tau site.

omega tau, hosted by Markus Völter, covers a wide variety of topics from engineering and science. It’s one of my favorite podcasts, so I would encourage you to not only listen to this episode, but subscribe to the podcast.

X-class solar flare causes radio blackout


(Image source: Screen capture from NASA video)

(Source: Discovery News)

The sun has erupted with its first X-class solar flare of 2015, a not-so-subtle reminder that it can still muster the energy required to generate the most powerful class of solar explosion.

The magnetic eruption occurred yesterday (Wednesday) at 12:22 p.m. ET (16:22 UT), lighting up a huge area in the lower solar corona (the sun’s magnetically dominated ‘atmosphere’). Shortly after the huge eruption, that measured X2 on the scale of flare energy, Spaceweather.com reports a radio blackout was detected over large swathes of the globe, including much of the Americas.

“The X-flare scrambled the ionosphere thoroughly so that no decametric radio signals were supported in my part of the world,” said amateur radio astronomer Thomas Ashcraft. “The ionosphere started to reform after about fifteen minutes when stations began to reappear. (The stuff visible during the blackout was my own observatory electricity. Nothing exterior.)”

Based in New Mexico, Ashcraft reports that the blackout was most obvious in the frequency range of 15 MHz to 26 MHz.

[Continue reading at Discovery News…]

Good news? There may be some HF band openings in the wake of this flare. We shall see.

The Juno Earth Flyby QSL card

Happiness is receiving the Juno Earth Flyby QSL card in the mail:



Many thanks to the NASA Jet Propulsion Laboratory for making the Juno Flyby such a fun experiment. To read more about the flyby, check out our post from last year.

Were any readers able to “work” the Juno spacecraft?