Hi. Welcome on insane curiosity.
Today we are going to talk about the detection of a radio signal from the Venus Ionosphere.
The detection was made possible thanks to NASA’s Parker Solar Probe.
We’ll tell you later why this is an important discovery.
But first…what do you know about Venus? Here are some quick interesting facts.
1) A day on Venus is longer than a year on Earth.
2) With a mean temperature of 462°C, Venus is hotter than Mercury, despite being further
away from the Sun. 3) Unlike the other planets in our solar system,
Venus spins clockwise on its axis. 4) Venus is named after the Roman Goddess
of love and beauty due to its bright, shining appearance in the sky. Of the five planets
known to ancient astronomers, it would have been the brightest.
5) A hypothetical inhabitant of Venus would be called Venusian, and not Venerian.
Ok, now that we know something more about Venus, we need to take a quick look at what
an Ionosphere is. In fact, if we want to understand the detection
of the radio signal on Venus, we have to recall some basic information about the ionosphere.
Talking about Earth’s ionosphere, it is the belt of the Earth’s atmosphere in which
the radiations of the Sun, and to a much lesser extent the cosmic rays coming from
space, cause the ionization of the component gases. Extending between 60 and 1000 km of
altitude and therefore partially belonging to both the mesosphere and the thermosphere,
it can be further divided into layers highlighting the different electrical properties, due to
variations in composition and intensity of solar radiation received.
The Earth’s ionosphere:
1. It’s home to all the charged particles in Earth’s atmosphere
The Sun cooks gases there until they lose an electron or two, which creates a sea of
electrically charged particles 2. It changes — sometimes unpredictably
Because it’s formed when particles are ionized by the Sun’s energy, the ionosphere changes
from Earth’s dayside to the night side. 3. Disturbances there can disrupt signals
The ionosphere also plays a role in our everyday communications and navigation systems. Radio
and GPS signals travel through this layer of the atmosphere or rely on bouncing off
the ionosphere to reach their destinations. In both cases, changes in the ionosphere’s
density and composition can disrupt these signals.
4. The ionosphere constantly glows And the airglow isn’t just a beautiful sight:
It’s a useful marker for what happens in the ionosphere. Each atmospheric gas has its own
favoured airglow colour depending on the gas, altitude region, and excitation process, so
we can use airglow to study where these gases are and how they behave.
This is all we needed in order to understand what Parker Solar Probe just discovered about
the Venusian Ionosphere! Let’s start.
During a close flyby of the planet Venus in July 2020, Nasa’s parker solar probe detected
something very odd as it dipped just 517 miles above the Venusian surface.
Its probe instruments recorded a low-frequency radio signal. This meant Parker had just skimmed
into the Venusian ionosphere. This was an exciting achievement because it
was the first time an instrument was able to collect in-situ measurements of venus’
upper atmosphere. The last time was about three decades ago.
These are precious data, that could definitely help us take away some doubts about the nature
of our “twin planet”.
Astronomer Lynn Collison from Nasa said he was just so excited to have new data from
Venus, and we share the same thought with him because Venus is a fascinating world to
us here on earth. In fact, it is so similar to our own planet
in size – with a radius of 6.051,8 km, just a little shorter than the Earth Radius) and
composition (it’s a rocky planet!). But despite that, Venus is so crucially different
It is toxic, and it is a hot hell world that’s likely completely inhospitable to life as
we know it.
Scientists are trying to understand how the two planets could have developed into such
different worlds. This is a wonder of deep interest to astrobiologists
too, that are searching for other habitable worlds out there in the universe.
By the way, every time we add some new understanding about Venus, we are excited.
This is because it’s hard to explore the secrets of Venus: missions to explore Venus have been
relatively few because landers can’t survive the planet’s huge 864 degrees Fahrenheit
surface, or 462 degrees celsius. This is also one of the reasons why we have a lot of landing
missions directed to Mars rather than to Venus. Also, the incredibly thick atmosphere of carbon
dioxide and sulfuric acid rain clouds is dangerous for probe’s missions.
This is what makes it hard to tell what is happening on the venus surface.
From all the missions sent to Venus, we want to recall the Pioneer mission.
Pioneer — Venus 1 Orbiter The Pioneer — Venus orbiter carried a radar
altimeter, which was used to make the first global map of the surface elevations. The
orbiter’s main antenna was used to produce moderate-resolution radar images of the equatorial
Pioneer — Venus 2 Bus and Landers
The Pioneer-Venus bus carried and released four probes, which measured the atmospheric
composition, temperature, and pressure as they descended toward a hard landing on the
surface. Anyway, for these reasons, Venus has not been
a popular target for dedicated missions. Most of the information we know about Venus come
in fact from missions that didn’t set the study of Venus as a primary goal.
This was exactly the case of the radio signal detected by Parker Solar Probe: Parker solar
probe was …not meant for Venus…so how did they detect the radio signal?
As Parker conducted its mission to study the sun in close detail, it used Venus for gravity-assist
manoeuvres slingshotting around the planet to alter velocity and trajectory.
It was one of these gravity assist flybys that the probe’s instruments recorded the
radio signal from Venus.
Sometimes, when we hear about radio signals from other planets, we think about the possibility
of the existence of a form of life that is trying to communicate with us.
So was it a communication radio signal? Well, it seems not…why?
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Scientist Collison, who has worked on other planetary missions, noted that the detection
of the signal recalled another episode of his life…
It was pretty the same kind of signal recorded by the Galileo probe when it skimmed through
the ionosphere of Jupiter’s moons, a layer of atmosphere also seen on earth at Mars,
where solar radiation ionizes the items resulting in a charged plasma that produces low frequency,
I know what you’re thinking: ok, we detected a radio signal from Venus, but why is it so
important for us? Well, the answer is that once the researchers
realized what the signal was, they were able to use it to calculate the density of the
Venusian ionosphere and compare it to the last direct measurements taken all the way
back in 1992. Fascinatingly, the ionosphere was an order of magnitude thinner in the new
measurements than it was in 1992.
The team believes that this has something to do with solar cycles.
The solar cycle or solar magnetic activity cycle is a nearly periodic 11-year change
in the Sun’s activity measured in terms of variations in the number of observed sunspots on
the solar surface. Sunspots have been observed since the early 17th century and the sunspot
time series is the longest continuously observed (recorded) time series of any natural phenomena.
The magnetic field of the Sun flips during each solar cycle, with the flip occurring
when the sunspot cycle is near its maximum. Levels of solar radiation and ejection of
solar material, the number and size of sunspots, solar flares, and coronal loops all exhibit a
synchronized fluctuation, from active to quiet to active again, with a period of 11 years.
This cycle has been observed for centuries by changes in the Sun’s appearance and by
terrestrial phenomena such as auroras. Solar activity, driven both by the sunspot cycle
and transient aperiodic processes govern the environment of the Solar System planets by
creating space weather and impact space- and ground-based technologies as well as the Earth’s
atmosphere and also possibly climate fluctuations on scales of centuries and longer.
Understanding and predicting the sunspot cycle remains one of the grand challenges in astrophysics
with major ramifications for space science and the understanding of magnetohydrodynamic
phenomena elsewhere in the Universe.
Skywave modes of radio communication operate by bending radio waves through the Ionosphere.
During the “peaks” of the solar cycle, the ionosphere becomes increasingly ionized by
solar photons and cosmic rays. This affects the propagation of the radio wave in complex
ways that can either facilitate or hinder communications. Forecasting of skywave modes
is of considerable interest to commercial marine and aircraft communications, amateur radio operators and shortwave broadcasters.
These users occupy frequencies within the High Frequency or ‘HF’ radio spectrum that is
most affected by these solar and ionospheric variances. Changes in solar output affect
the maximum usable frequency, a limit on the highest frequency used for communications.
Anyway, measurements of Venus from Earth suggested that Venus’s ionosphere was changing in
sync with the solar cycles, growing thicker at solar maximum and thinner at solar minimum,
but without direct measurements, it was difficult to confirm.
So they went back to 1992 measurements. In 1992, the Sun was close to solar maximum.
The 2020 measurement close to the solar minimum, and they were both consistent with the earth-based
measurements. “When multiple missions are confronted confirming
the same result, one after the other, that gives you a lot of confidence that thinning
This is what astronomer Robin Ramstad of the university of colorado says.
The question now is… How can the solar cycle affect in such a fascinating
way the ionosphere of Venus? Scientists say they have two leading theories.
The first is that the upper boundary of the ionosphere could be compressed to a lower
altitude during solar minimum. This would prevent atoms ionized on the dayside from
flowing to the night side, resulting in a thinner, nightside ionosphere.
Unfortunately, neither of these mechanisms could be ruled out by the Parker data, but
the team hopes that future missions and observations might be able to clarify what’s going on
in turn. Here’s where all the importance of this discovery
lies: a new and better understanding of the Venusian ionosphere could help us to gain
a better understanding of why venus is the way it is compared to our Earth.
And since a lot of planets shares common ionosphere features, this could also bring new knowledge
in the field of exoplanets.
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