Photons enter into GLOWSThe GLObal Solar Wind Structure (GLOWS) instrument investigates the structure of the solar wind and how it shifts during the solar cycle. GLOWS also investigates the distribution of the helioglow found in the extreme ultraviolet (EUV) range of the Sun’s light using a non-imaging single-pixel photometer that will collect and count Lyman-α photons found in the helioglow as IMAP spins on its axis. through a collimatorA device at the entrance to a sensor instrument that narrows a beam of particles or waves, such as light or energetic neutral atoms, into a more parallel or aligned stream. This helps improve the precision and accuracy of measurements or imaging by reducing the spread of the beam; the “gateway” into a sensor. 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-viewThe area or region that can be observed or captured by a particular instrument or sensor. 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 multiplierA device used in particle detectors and imaging systems that amplifies the number of electrons, making it easier to detect and measure the weak signals; also called channel multiplier. CEMs can also detect photons, but amplifying the electron given off by the photon through the photo-electric effect. (CEMA Channel Electron Multiplier is a device used in particle detectors and imaging systems that amplifies the number of electrons, making it easier to detect and measure the weak signals; also called channel multiplier. CEMs can also detect photons, but amplifying the electron given off by the photon through the photo-electric effect.). Electrons are so tiny, it is difficult to count them individually, so they need to be multiplied into electronA negatively charged elementary particle that normally resides outside (but is bound to) the nucleus of an atom. 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 photonThe smallest possible particles of electromagnetic energy and therefore also the smallest possible particles of visible light. Photons have no mass or charge. They correspond to a single wavelength, but exist across the entire spectrum of electromagnetic radiation. hits the detectorAn instrument which is used to discover that something is present somewhere, or to measure how much of something there is. 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.

Learn more about glows

The luminosityThe absolute measure of the radiant power emitted by a light-emitting object. The Sun's luminosity is about 4x1026 watts. of the helioglowThe helioglow results from the interaction between interstellar neutral hydrogen atoms (ISN H), uncharged particles from outside our solar system, and a specific type of photon found in the Sun’s light emissions. These photons, called Lyman- α photons, are found in a narrow band of UV light that is invisible to human eyes. Occasionally, an ISN H atom that passed through the heliosphere boundary is excited by a Lyman-alpha photon, briefly boosting it into a higher energetic state. The atom can't be excited for very long, so it almost immediately drops back to the lowest energetic state, emitting a Lyman-α photon to take away this extra energy. The re-emitted photons form what we call the helioglow. Because UV light is invisible to human eyes, we can't see the helioglow, but we can detect it. The GLOWS instrument uses special sensors designed to collect and count the glowing particles that have a very specific amount of excited UV energy. depends on the concentrationThe amount of a substance found in a defined space. of the ISN HInterstellar neutral hydrogen is a normal hydrogen atom consisting of a single proton-electron pair, making it neutral, or without a charge. It is the most abundant species of gas found in the ISM, as well as the outer heliosheath and local interstellar medium (LISM). 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 windA stream of charged particles, mostly protons and electrons, that escapes into the Sun's outer atmosphere at high speeds and streams out into the solar system in all directions. found throughout interplanetary spaceThe area of space found surrounding and between planets of a star system. 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 distributionThe number of specified items or components found in a defined space. IMAP scientists can find out how much of the solar neighborhood is made up of ISN H.

Meet the Team

GLOWSThe GLObal Solar Wind Structure (GLOWS) instrument investigates the structure of the solar wind and how it shifts during the solar cycle. GLOWS also investigates the distribution of the helioglow found in the extreme ultraviolet (EUV) range of the Sun’s light using a non-imaging single-pixel photometer that will collect and count Lyman-α photons found in the helioglow as IMAP spins on its axis. 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 timeA measure of the flow of events. that an EUV detectorAn instrument which is used to discover that something is present somewhere, or to measure how much of something there is. 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