We already looked at spacecrafts at some planets in our solar system. But we haven’t covered all of them. Let’s take a look at the other inner planets. Are there spacecrafts at Mercury or Venus? Or maybe even somewhere in between the planets? Do you know? Let’s find out!
BepiColombo en route to Mercury
Let’s start with the planet closest to the Sun, Mercury. On 20 October 2018 ESA launched its first mission to the planet called BepiColombo. It will, however, not be the first visit to Mercury from planet Earth. In 1974 NASA’s Mariner 10 and in 2008/2009 NASA’s MESSENGER already visited Mercury. There probably haven’t been more mission because Mercury is a difficult target. Its proximity to the Sun makes it challenging to reach and hard for a spacecraft to survive the heat and the radiation. We’ll see how well BepiColombo does, when it reaches Mercury in 2025.
Although I wrote it’s an ESA mission, it really is a cooperation between ESA and JAXA. With both agencies providing spacecrafts to the mission. The Mercury Magnetospheric Orbiter (Mio) is from JAXA. The Mercury Planetary Orbiter (MPO) is from ESA. ESA also provided the Mercury Transfer Module (MTM) and the Magnetospheric Orbiter Sunshield and Interface Structure (MOSIF). The Mercury Transfer Module provides solar-electric propulsion and other services required for the transit to Mercury. It will be jettisoned before arrival in orbit around Mercury. Between the jettison of MTM and the arrival in its scientific orbit, MPO provides everything Mio needs. This is done through the MOSIF, which also provides thermal protection for Mio. After separation of Mio and MPO, MOSIF is no longer required and will be jettisoned as well.
Instruments
Let’s take a look at the spacecrafts and their instruments. We’ll start with MPO. It carries 11 instruments, which are:
- BepiColombo Laser Altimeter (BELA)
- Italian Spring Accelerometer (ISA)
- Magnetic Field Investigation (MPO-MAG)
- Mercury Radiometer and Thermal Imaging Spectrometer (MERTIS)
- Mercury Gamma-Ray and Neutron Spectrometer (MGNS)
- Mercury Imaging X-ray Spectrometer (MIXS)
- Mercury Orbiter Radio science Experiment (MORE)
- Probing of Hermean Exosphere by Ultraviolet Spectroscopy (PHEBUS)
- Search for Exosphere Refilling and Emitted Neutral Abundances (SERENA)
- Spectrometers and Imagers for MPO BepiColombo Integrated Observatory (SIMBIO-SYS)
- Solar Intensity X-ray and particle Spectrometer (SIXS)
Mio, on the other hand, carries 5 more instruments to study Mercury:
- Mercury Magnetometer (MMO-MGF)
- Mercury Plasma Particle Experiment (MPPE)
- Mercury Plasma Wave Instrument (PWI)
- Mercury Sodium Atmospheric Spectral Imager (MSASI)
- Mercury Dust Monitor (MDM)
As those are quite many instruments, I suggest taking a look at ESAs website for more details about each instrument on Mercury Planetary Orbiter and Mercury Magnetospheric Orbiter. Let me know in the comments, if I should go into all the details.
If you want to know where BepiColombo currently is, ESA provides a website which allows you to track the location and progress of the mission. While we continue on to another planet in the solar system, Venus.
Akatsuki (or Planet-C / Venus Climate Orbiter) at Venus
Akatsuki or Planet-C is an example that you shouldn’t give up a mission, even if there is a setback. But let’s start at the beginning. The mission launched on 21 May 2010 onboard a H-IIA. It arrived at Venus on 6 December 2010 (UTC) and fired its engine. Unfortunately, the orbit insertion failed, because of a malfunction in the propulsion system. However, on 7 December 2015 it came close to Venus again. This time it fired it navigation thrusters and successfully entered into an orbit.
The main goal of the mission is to study the atmosphere in general and the motions of the atmosphere specifically. Therefore, it is equipped with six instruments. Let’s take a look at them.
- Ultraviolet imager (UVI)
It measures the distribution of sulfur dioxide as well as wind speeds by observing dark-and-light pattern. - 1 µm camera (IR1)
This instrument can see through the clouds and observe movement of clouds in the lower atmosphere, measure water vapor and the mineral composition of the surface - 2 µm camera (IR2)
This camera observes the formation of clouds as well as the distribution of particles and molecules (e.g. carbon monoxide) - Long-wave infrared camera (LIR)
It makes two-dimensional temperature maps of the cloud tops - Lightning and airglow camera (LAC)
A high-speed camera that can observe lightning in the atmosphere - Ultra-stable oscillator (USO)
This instruments analyses how radio signals from earth change, when Akatsuki is behind Venus (as seen from Earth). This allows to measure temperature profiles and sulphuric acid vapor in the atmosphere
Now, let’s take a look at spacecraft orbiting the sun.
Parker Solar Probe
On 12 August 2018 a Delta IV-Heavy launched NASA’s Parker Solar Probe. The rocket carried an additional Star-48 solid motor as a third stage to achieve the required orbit. The spacecraft will use Venus’ gravity during seven flybys to bring its orbit closer to the sun. This process will take nearly seven years. Finally, Parker Solar Probe will be in an orbit that on closest approach takes it within 6.2 million kilometers. Closer to the Sun than any spacecraft before.
The main mission of the spacecraft is to study the Sun’s atmosphere. Therefore, it even “touches the Sun” by diving into its atmosphere. This, however, exposes the spacecraft to quite extreme condition. The temperatures can, for example, reach more than 1,300 degrees Celsius. As engineers, however, knew what to expect, they protected Parker Solar Probe with a carbon-composite shield. And on 28 April 2021 Parker Solar Probe demonstrated, that it can survive, when it entered the Sun’s atmosphere for the first time. If you want to know more about this event, read the blog post from NASA.
The main goal of the mission is to answer three main questions. Why is the corona much hotter than the Sun’s surface (the photosphere)? How does the solar wind accelerate? What are the sources of high-energy solar particles?
Instruments
Therefore, it carries four scientific instruments. Here’s a quick summary about each. If you want to know more about the instruments, take a look at this page about them.
- FIELDS – Fields Experiment
The Fields Experiments studies scale and shape of electric and magnetic fields. It can, for example, make high-speed observations of waves and turbulences in the inner heliosphere. - WISPR – Wide Field Imager for Solar Probe
The Wide Field Imager provides the big picture of the environment. It takes images of the corona and solar wind before the spacecraft enters them. - SWEAP – Solar Wind Electrons Alphas and Protons
The Solar Wind Electrons Alphas and Protons experiments consists of two instruments, the Solar Probe Cup, and the Solar Probe Analyzers. They count particles like electrons, protons, and helium ions. In addition, they measure the velocity, density, and temperature of these particles. - ISʘIS – Integrated Science Investigation of the Sun
The Integrated Science Investigation of the Sun also consists of two instruments, which measure particles across a wide range of energies. This helps to understand their lifecycle. Including where they came from, how they became accelerated and how they move out from the Sun.
The Sun is also the target of our last spacecraft for the day. So, let’s take a look at Solar Orbiter.
Solar Orbiter
On 10 February 2020 ESA’s Solar Orbiter launched onboard an Atlas-V provided by NASA. Why would an ESA mission launch on a rocket provided by NASA, you ask? Because the mission is a cooperation between ESA and NASA. Where ESA provides the main parts of the spacecraft as well as the mission and science operation, while NASA provides the launch vehicle. This is quite common. For example, for the James Webb Space Telescope it was basically the other way around, the spacecraft from NASA and the rocket from ESA.
Solar Orbiter is a follow-up mission to spacecrafts like Helios, Ulysses, or SOHO. With later spacecraft still operating at Sun-Earth L1. You can find more about it in a previous post. The main goal of the mission is to study how the inner heliosphere works and how solar activities affect it. Therefore, the spacecraft has two kinds of instruments, in-situ instruments and remote sensing ones. The in-situ instruments work full-time, while the remote sensing ones are limited to 30 days each orbit.
Instruments
The four in-situ instruments are:
- Energetic Particle Detector (EPD)
A detector to measure composition, timing and distribution of particles. - Magnetometer (MAG)
A high-precision magnetometer to measure heliospheric magnetic fields. - Radio and Plasma Waves (RPW)
The Radio and Plasma Waves experiment measures magnetic and electric fields. It also makes remote sensing measurements. - Solar Wind Analyser (SWA)
The Solar Wind Analyser will measure the ion and electron properties of the solar wind. In addition it willmeasure it’s ion composition.
Let’s take a look at the six remote-sensing instruments:
- Extreme Ultraviolet Imager (EUI)
The Extreme Ultraviolet Imager will provide image sequences of the atmospheric layers above the photosphere. - Coronagraph (Metis)
Metis will take images of the solar corona. It will simultaneously provide images in visible and ultraviolet bands. - Polarimetric and Helioseismic Imager (PHI)
The Polarimetric and Helioseismic Imager will provide high-resolution and full-disc images. - Heliospheric Imager (SoloHI)
The Heliospheric Imager will observe visible sunlight and how it is scattered by solar wind electrons. - Spectral Imaging of the Coronal Environment (SPICE)
SPICE will perform extreme ultraviolet imaging spectroscopy of the Sun. - X-ray Spectrometer/Telescope (STIX)
STIX makes imaging spectroscopy of solar thermal and non-thermal X-ray emission.
That’s quite a list of numerous instruments to further study are Sun. So, let’s sum up, what we learned so far.
Summary
Yes, there are more mission focussing on Mars, but we’re also exploring the other planets in our solar system, as well as the Sun itself. With Parker Solar Probe and Solar Orbiter, we have two more missions with a different angle on the Sun. Adding their results to the results of spacecrafts near the Earth. As the Sun and its activities are more important to our life on Earth as you might think.
So far, we took a look at spacecrafts at the Moon, near the Earth, at Mars and on the surface of Mars. But there is more to discover. So next time we take a look at spacecraft further out in the solar system and beyond.
Find out more about What’s happening beyond low earth orbit.
Image at the top via Good Free Photos