An instrument built by Imperial physicists is on its way to be fitted onto NASA’s Interstellar Mapping and Acceleration Probe (IMAP) spacecraft.

The Imperial-built instrument, called MAG, will play a key role in helping IMAP study the solar wind following its launch in 2025. MAG is a magnetometer, which measures the local magnetic field. 

MAG was built and tested over the past two years and is now ready to be fitted on the IMAP spacecraft, which is being assembled at the Johns Hopkins University Applied Physics Lab (APL) in Maryland, USA. 

IMAP will observe and map the Sun’s heliosphere – the volume of space filled with particles streaming out from the Sun, known as the solar wind – and study how it interacts with the local galactic neighbourhood beyond, known as the interstellar medium. 

Studying the heliosphere and its interactions with the interstellar medium is critical for understanding the radiation and space environment throughout the inner solar system, and our solar system’s home within the galaxy. 

Imperial’s MAG instrument will contribute to understanding the acceleration and transportation of charged particles in the heliosphere. It will do this by measuring the interplanetary magnetic field around the spacecraft. From these measurements, MAG will identify interplanetary shocks and measure the waves and turbulence that scatter particles in the solar wind. 

All coming together 

The construction of MAG is funded by the UK Space Agency. As well as providing the instrument, Imperial will provide ground support and personnel necessary to support the instrument and the IMAP science team. Of the 10 instruments aboard IMAP, eight will be built in the US, one in Poland, and one, MAG, in the UK. 

Science Lead for the IMAP MAG Professor Tim Horbury, from the Department of Physics at Imperial, said: “It’s been a delight to interact will all the mission partners, including really supportive interactions with the UKSA, and to see the project moving productively forward. 

“Every day there is something new happening with the spacecraft and it’s incredible to know it will be our turn next.”

Dr Paul Bate, Chief Executive of the UK Space Agency, said: “The work by the Imperial team on this instrument is crucial to IMAP’s ability to show us how particles behave in the heliosphere, providing an excellent example of how important UK expertise are to major international space science missions.  

“The UK Space Agency provided funding for MAG through our National Space Innovation Programme, dedicated to supporting ambitious British projects with the potential to transform applications and services for the global space community. It builds on previous investment in magnetometer technology at Imperial, helping to foster UK expertise and maximise the space sector’s long-term growth.” 

Record build 

The Imperial team built MAG in record time, taking just three years from funding to instrument delivery, positioning it to be the second instrument mounted onto the spacecraft. Part of the success was due to re-using much of the design from a previous MAG built at Imperial, and currently flying on the European Space Agency Solar Orbiter mission.  

The build wasn’t without challenges though. Professor Horbury and Instrument Manager Helen O’Brien had to hire a whole new team and get them up to speed in the building and testing of such an instrument, beginning during the pandemic. Once built, the instrument had to go through a number of tests in facilities across France, Germany and the UK to ensure it could survive the launch and the conditions it will face out in space.

O’Brien said: “Through all of the tests – including vibration, calibration, thermal vacuum cycling and electromagnetic compatibility – the instrument performed brilliantly, measuring the magnetic field and remaining unchanged by all the pain and suffering we put it through. It’s a real testament to the Imperial engineering team.”

Getting on board 

Once MAG reaches APL, it will go through a few more trials and tests. First, it will be ‘baked’ for two weeks in a thermal vacuum chamber to remove any organic materials. This is to ensure cleanliness as some other instruments would be very affected by contamination. For example, the Interstellar Dust Experiment (IDEX) will measure individual atoms’ speed and composition, meaning it will be extremely sensitive to any contamination introduced by other parts of the spacecraft. 

MAG will then go through a few compatibility tests before the electronics box, which receives and processes data from the magnetic field sensors, is mounted on the spacecraft. Professor Horbury said: “Seeing the instrument talk to the spacecraft for the first time will be important and really exciting.” 

APL has a live feed of the spacecraft clean room – keep an eye out in the next few weeks for MAG being integrated. 

To protect them from magnetic fields from the spacecraft, the MAG’s sensors will be mounted on a long ‘boom’ sticking out from the main body later in the summer. Once everything is assembled, IMAP will head to NASA’s Goddard Space Flight Center for final testing prior to launch in spring 2025. 

The Imperial team will not be idle while the other instruments are mounted though; they will be simulating operations for the spaceflight, including how to control the instrument from the ground and how to get the data and process it. 

About IMAP 

Princeton University professor David J. McComas leads the mission with an international team of 25 partner institutions. The Johns Hopkins Applied Physics Laboratory in Laurel, Maryland builds the spacecraft and operates the mission. IMAP is the fifth mission in NASA’s Solar Terrestrial Probes (STP) Program portfolio. The Explorers and Heliophysics Project Division at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the STP Program for the agency’s Heliophysics Division of NASA’s Science Mission Directorate.