GLOWS Instrument
The GLObal Solar Wind Structure (GLOWS) instrument investigates the structure of the solar wind - how it varies from one solar pole to the other - and how it shifts during the solar cycle. To that end, GLOWS looks at the distribution of the helioglow - illumination that occurs when interstellar neutral hydrogen atoms (ISN H) from outside our solar neighborhood are excited by Lyman-α photons found in the extreme ultraviolet (EUV) range of the Sun’s light. While this narrow band of sunlight is invisible to human eyes, it can be detected. To do this, GLOWS uses a non-imaging single-pixel photometer that collects and counts Lyman-α photons as IMAP spins on its axis.
How It Works
Photons enter into GLOWS through a collimator shaped like a bundle of straws surrounded by a baffle painted with a special black paint. The baffle and collimator work together to keep out stray light and allow the tiny photons in GLOWS’ field-of-view into the instrument and towards the filter. This filter behind the collimator allows only the Lyman- α photons through into the instrument.
GLOWS counts bunches of electrons released when these photons impact the channel electron multiplier (CEM). Electrons are so tiny, it is difficult to count them individually, so they need to be multiplied into electron impulses using a CEM. GLOWS CEM is made of a curved funnel-shaped glass tube that has a voltage applied to it. When a Lyman-α photon hits the detector surface behind the collimator, a small cloud of electrons is knocked out. These electrons are accelerated by the voltage as they travel from one end of the detector to the other. Along the way, the electrons continue to bump into the walls of the glass channel knocking even more electrons out, multiplying them. At the end, a huge electron cloud is formed, which is detected as an electric impulse that counts each cloud for each photon.
Photons enter the GLOWS instrument at the rate of about 1000 per second, so the scientists are able to count each photon individually.
Explore the GLOWS Model
How We Use GLOWS Data
The luminosity of the helioglow depends on the concentration of the ISN H atoms for Lyman- α photons to excite. In some locations in the solar system there are more of ISN H atoms, in some other locations less, and as a result, the brightness of the helioglow is distributed in the sky unevenly. Some ISN H atoms are ionized when they bump up against the charged particles of the solar wind found throughout interplanetary space and can no longer be excited by the Lyman- α photons. The helioglow brightness is related to the amount of ISN H in a given area of the sky: the brighter the glow, the more the ISN H is present. The dimmer the glow, the lesser the ISN H. By looking at this brightness distribution IMAP scientists can find out how much of the solar neighborhood is made up of ISN H.
Meet the Team
GLOWS is contributed by Space Research Center of the Polish Academy of Sciences (CBK PAN) under the leadership of Maciej Bzowski. They also provide ground support and the necessary personnel to support the instrument and the IMAP science team. The GLOWS team involves 5 scientists, about 20 engineers, and supporting personnel from CBK PAN as well as partners from Polish and international institutions: WAT (Military Technical University in Warsaw), Physikalisch-Technische Bundesanstalt in Berlin, Germany, and Bonn University, Germany, for EUV metrology and instrument calibration, and Spacive, Warsaw, Poland (thermal experts).
Space Research Centre of the Polish Academy of Sciences (CBK PAN) has more than 45 years of experience delivering space instrumentation for space missions. However, this is the first time that an EUV detector has been developed by CBK PAN. It was designed in-house specially for the IMAP mission and despite being a prototype it works according to expectations and was delivered to the spacecraft for integration as scheduled. The CBK PAN team is proud an overjoyed that we are not behind the other IMAP instrument teams with a much larger experience and flight instrument heritage even though we had to master an experimental technique we had never used previously, when our original German partners were denied funding and had to withdraw from the project. Lessons learned on GLOWS are a valuable extension of the knowledge database and heritage that has been accumulated at CBK for almost 50 years.
This is part of my life. I don't need an extra stimulation or motivation because this is just part of my personality, doing that science, and in particular, doing that science I'm able to do with IMAP... I'm really privileged because I have first-hand access to data from more than one experiment, which I feel I understand real well and I can interpret. I also can convey some of this knowledge or experience to younger people.
-Maciej Bzowski, Instrument Lead, GLOWS
NASA Administrator Bill Nelson visited CBK PAN in Poland in early June 2023. The IMAP GLOWS team was able to share with him about the GLOWS instrument and discuss the upcoming IMAP mission.