Juice towards the first of its kind Moon-Earth flyby – Swedish instruments in operation
On August 19-20, Juice, as the first spacecraft ever, will use the Moon and 1.5 days later the Earth, for gravity assistance. With the flybys, Juice saves a large amount of fuel for the remaining journey to Jupiter which will be reached in July 2031. The Swedish Institute of Space Physics (IRF) will have its instruments operating during the flybys.
Juice began its eight-year journey towards Jupiter and the three icy moons Europa, Ganymede and Callisto on April 14, 2023, and the European Space Agency ESA has planned in detail how the spacecraft will travel.
The two close flybys of the Moon and Earth (Lunar-Earth gravity assist, LEGA) will give Juice the extra energy that the spacecraft needs to propel itself on its journey. Flybys are also planned of Venus in August 2025, Earth in September 2026 and Earth in 2029.
Planned measurements for IRF’s instruments
For IRF, which is responsible for two of the ten instrument packages on board Juice, the flybys mean valuable instrument calibrations for the Particle Environment Package, (PEP) and Radio and Plasma Wave Investigation, (RPWI) instrument packages.
Professor Stas Barabash, IRF scientist in Kiruna, is Principal Investigator for PEP.
“Four of PEP’s six particle instruments will conduct flyby measurements of the Moon and Earth to calibrate the instruments against their space environment. Measurements at the Moon are of particular interest to IRF. A new space race is ongoing and studying and understanding the Moon is a strategically important goal for the institute to continue to be a world-leading space research organization”, he says.
For example, the Kiruna-built PEP instrument Jovian plasma Dynamics and Composition analyzer (JDC) will measure heavy ions from the Moon with a high mass resolution, while another PEP instrument will focus on the electrons in the lunar environment.
The flyby of the Earth means that several of the PEP instruments get the opportunity to calibrate its measurement sensors against the Earth’s radiation belts. It will be the first time that the measurement sensors are exposed to a radiation environment before reaching Jupiter, which has the most extreme radiation environment in the solar system.
Assoc. prof. Jan-Erik Wahlund, IRF scientist in Uppsala, is Principal Investigator for RPWI.
“RPWI has ten sensors on masts and antennas and four different instruments to measure space plasma and electric and magnetic fields in three dimensions. Most of the functions of RPWI will be tested both around the Moon and the Earth, but also later in the solar wind. Above all, we hope to measure dust around the moon and the conductivity of the lunar surface”, he says.
When Juice flies past Earth, the plan is for RPWI to receive radio waves from Earth via the High-frequency Active Auroral Research Program, HAARP, facility in Alaska. Hopefully the direction of radio radiation from the aurora borealis can also be determined to further calibrate the instrument package for the measurements that await at Jupiter.
More information
- IRF: IRF i rymden - Juice
- ESA:
Contact:
- Professor Stas Barabash, Swedish Institute of Space Physics, Kiruna, Principle Investigator for Particle Environment Package (PEP)
- Assoc. Prof., Jan-Erik Wahlund, Swedish Institute of Space Physics, Uppsala, Principle Investigator for Radio and Plasma Wave Investigation (RPWI)
