# Requirements to resolve position of Jovian Whistlers up to magnitude of Red Spot with amateur radio equipment?

Can I sense a bright star pointing an eight foot antenna towards it? is a while ago, but the discussion about this question I found very interesting. Please forgive me that I am not an expert in Jovian Whistlers but I tend to understand it as massive EM events on Jupiter.

I am wondering: Could we use a Yagi-Uda antenna or an array of it to resolve the source of the radio signals on Jupiter? For instance, we could have the Jupiter-disk covered by a square of $$40 \times 40$$ pixels, and the goal would be to figure out from which pixel the signal originated.

The idea behind that is that a cool research question for an (advanced) science project in school would be a question like "Did the lightning occur inside the Red Spot?" and Yagi-Uda antennas are fun to build, and do not require as much space as other antenna types.

### References

• you may be able to use your answer here together with the ProfRob answer I've linked to below calculate the complex dielectric constant $n + \text{i}k$ then use $I(x) = \left(\exp(-kr)/r\right)^2$ to see how the intensity varies with distance from Jupiter and to see when it is dominated by $1/r^2$ and when by exponential absorption. Feel free to post such an answer and accept it! (but don't blindly trust my math!) – uhoh Apr 27 at 4:11

### tl;dr

No, not from Earth.

Because of the ionosphere.

Whistlers are VLF (very low frequency) hundreds to thousands of Hertz. Our ionosphere blocks electromagnetic radiation very reliably below say roughly 10 MHz depending on time of day and solar activity because it's a plasma.

The image below shows peak whistler emissions at about 1 kHz.

You can imagine that the electrons in the ionosphere look more like electrons in a lossy metal to a radio wave in the kHz range; some will bounce off like it's a shiny metal marble, others will be absorbed, but without question None shall pass!

LOFAR works from 10 MHz to 250 MHz.

### Update!

No, not even from cis-lunar space!

Because the interplanetary electron density is still too high.

@ProfRob's comment on the "What can be learned..." question reminds us:

How low is "low"? The plasma frequency in the interplanetary medium near the Earth is about 100 kHz. https://physics.stackexchange.com/a/519164

and that answer goes into substantial detail on how to calculate the plasma frequency of various media.

The Chinese lunar orbiter Queqiao had a low frequency receiver, and backing up ProfRob's point:

Additionally, this satellite hosts the Netherlands–China Low-Frequency Explorer (NCLE), an instrument performing astrophysical studies in the unexplored radio regime of 80 kilohertz to 80 megahertz. It was developed by the Radboud University in Netherlands and the Chinese Academy of Sciences. The NCLE on the orbiter and the LFS on the lander work in synergy performing low-frequency (0.1–80 MHz) radio astronomical observations.

There are further references in the article.

It seems you must build a spacecraft and fly it into close proximity to Jupiter -- within a few attenuation lengths -- to hear the whistlers.

### More

Your reference Strong whistler mode waves observed in the vicinity of Jupiter’s moons links to the Open Access Nature paper Y. Y. Shprits et al. (2018) Strong whistler mode waves observed in the vicinity of Jupiter’s moons which includes Figure 2. shown below.