The Modular X- and Gamma-Ray Sensor (MXGS)of the ASIM Payload on the International Space Station

Anja Kohfeldt; Arne Solberg; Bilal Hasan Qureshi; Brant Carlson; Carl Budtz-J{\o}rgensen; Chris Eyles; Dominik Fehlker; Freddy Christiansen; Georgi Genov; Irfan Kuvvetli

arxiv: 1906.10452 · v1 · pith:RPFAOORRnew · submitted 2019-06-25 · ⚛️ physics.ins-det · astro-ph.IM· physics.space-ph

The Modular X- and Gamma-Ray Sensor (MXGS)of the ASIM Payload on the International Space Station

Nikolai {\O}stgaard , Jan E. Balling , Thomas Bj{\o}rnsen , Peter Brauer , Carl Budtz-J{\o}rgensen , Waldemar Bujwan , Brant Carlson , Freddy Christiansen

show 27 more authors

Paul Connell Chris Eyles Dominik Fehlker Georgi Genov Pawel Grudzi\'nski Pavlo Kochkin Anja Kohfeldt Irfan Kuvvetli Per Lundahl Thomsen S{\o}ren M{\o}ller Pedersen Javier Navarro-Gonzalez Torsten Neubert K{\aa}re Nj{\o}ten Piotr Orleanski Bilal Hasan Qureshi Linga Reddy Cenkeramaddi Victor Reglero Manuel Reina Juan Manuel Rodrigo Maja Rostad Maria D. Sabau Steen Savstrup Kristensen Yngve Skogseide Arne Solberg Johan Stadsnes Kjetil Ullaland Shiming Yang

This is my paper

Pith reviewed 2026-05-25 16:01 UTC · model grok-4.3

classification ⚛️ physics.ins-det astro-ph.IMphysics.space-ph

keywords MXGSASIMTGFTerrestrial Gamma-ray FlashesX-ray imaginggamma-ray spectroscopyInternational Space Stationlightning

0 comments

The pith

The MXGS instrument on the ISS will image and spectrally measure X- and gamma-rays from Terrestrial Gamma-ray Flashes to study their link with lightning and TLEs.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper introduces the Modular X- and Gamma-ray Sensor (MXGS) mounted on the Columbus module of the International Space Station as one half of the ASIM payload. MXGS is built to capture images and energy spectra of the high-energy photons emitted during lightning-related Terrestrial Gamma-ray Flashes. Its partner instrument MMIA handles optical imaging and fast photometry of Transient Luminous Events and lightning strokes. The combined system is presented as the first space mission equipped to examine the physical connections among electrical discharges, TLEs, and TGFs.

Core claim

MXGS is an imaging and spectral X- and Gamma-ray instrument mounted on the starboard side of the Columbus module on the International Space Station. Together with the Modular Multi-Spectral Imaging Assembly (MMIA), MXGS constitutes the instruments of the Atmosphere-Space Interactions Monitor (ASIM). The main objectives of MXGS are to image and measure the spectrum of X- and γ-rays from lightning discharges, known as Terrestrial Gamma-ray Flashes (TGFs), and for MMIA to image and perform high speed photometry of Transient Luminous Events (TLEs) and lightning discharges. With these two instruments specifically designed to explore the relation between electrical discharges, TLEs and TGFs, ASIM

What carries the argument

The MXGS detector system that performs simultaneous imaging and spectroscopy of X- and gamma-ray emissions from TGFs.

If this is right

Simultaneous X/gamma-ray and optical data will allow direct correlation of TGFs with specific lightning strokes and TLEs.
Energy spectra recorded by MXGS will constrain the production mechanism of the high-energy photons.
Imaging capability will reveal the spatial extent and location of TGF sources relative to the parent thunderstorm.
The mission will test whether TGFs, TLEs, and ordinary lightning form a single connected discharge process.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

Detection of consistent timing offsets between MXGS and MMIA signals could indicate the altitude at which TGFs are generated.
Long-term statistics from the ISS orbit might reveal whether TGF occurrence depends on latitude or season in ways ground networks cannot capture.
If TGF spectra extend to higher energies than expected, the data could require revisions to models of electron acceleration in thunderclouds.

Load-bearing premise

The MXGS instrument will achieve its required sensitivity, imaging resolution, and spectral coverage while operating on the ISS without major interference from the station environment or rapid degradation.

What would settle it

MXGS records no TGF events or shows no spatial and temporal overlap between its X/gamma-ray detections and MMIA observations of lightning or TLEs over the first year of operation.

read the original abstract

The Modular X- and Gamma-ray Sensor (MXGS) is an imaging and spectral X- and Gamma-ray instrument mounted on the starboard side of the Columbus module on the International Space Station. Together with the Modular Multi-Spectral Imaging Assembly (MMIA) (Chanrion et al. this issue) MXGS constitutes the instruments of the Atmosphere-Space Interactions Monitor (ASIM) (Neubert et al. this issue). The main objectives of MXGS are to image and measure the spectrum of X- and $\gamma$-rays from lightning discharges, known as Terrestrial Gamma-ray Flashes (TGFs), and for MMIA to image and perform high speed photometry of Transient Luminous Events (TLEs) and lightning discharges. With these two instruments specifically designed to explore the relation between electrical discharges, TLEs and TGFs, ASIM is the first mission of its kind.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

This is a standard instrument description paper for the MXGS detector on ASIM, focused on design specs and TGF/TLE objectives rather than new measurements.

read the letter

The core of this paper is a technical description of the MXGS X- and gamma-ray sensor mounted on the ISS Columbus module, paired with the MMIA for simultaneous TGF and TLE observations. It states the science goals clearly and notes that ASIM is the first mission built specifically for that combination of instruments. The design details on the modular setup, mounting, and expected spectral and imaging capabilities are the main content delivered here. That is useful for anyone tracking hardware for high-energy atmospheric events. The paper does a reasonable job laying out the configuration and calibration approach without overclaiming results. No new data or derivations appear, which matches the reader's note that this is not a measurement paper. The 'first of its kind' phrasing is a mission-context statement rather than a tested claim, and it holds up as a factual description of the payload pairing. Soft spots are minor and expected for this type of paper: performance numbers are prospective, with limited on-orbit verification or background rejection details supplied in the text. The assumption that ISS interference will not degrade sensitivity is stated but not quantified here. Readers working on similar detectors or planning follow-on analysis will find the subsystem breakdown and objectives section worth having. This is not for a general audience or for citing as a scientific result. It is the kind of paper that belongs in the instrumentation literature. I would send it to peer review so the design choices and expected performance envelope can be checked by specialists before flight data papers appear.

Referee Report

1 major / 1 minor

Summary. The manuscript describes the design, configuration, subsystems, calibration approach, and expected performance of the Modular X- and Gamma-Ray Sensor (MXGS), an imaging and spectral X- and gamma-ray instrument mounted on the starboard side of the Columbus module on the ISS. Together with the MMIA, it forms the ASIM payload whose objectives are to image and measure the spectrum of X- and gamma-rays from TGFs and to explore relations between electrical discharges, TLEs, and TGFs; the paper states that ASIM is the first mission of its kind for this purpose.

Significance. If the described design and performance envelope are realized on orbit, the work is significant for documenting a new capability in high-energy atmospheric physics. The technical details on an instrument specifically optimized for TGF detection and imaging from the ISS will be of direct use to the community studying lightning-related phenomena and for planning follow-on missions.

major comments (1)

[Abstract] Abstract: the stated objectives and configuration are clearly presented, but the manuscript provides no quantitative performance data, error budgets, or verification results to support the claimed sensitivity, imaging resolution, and spectral coverage for TGF detection. This information is load-bearing for evaluating whether the instrument can meet its scientific goals in the ISS environment.

minor comments (1)

The citations to companion papers (Chanrion et al. this issue; Neubert et al. this issue) are appropriate for a special-issue context but would benefit from a brief sentence clarifying the data synergy between MXGS and MMIA.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the positive evaluation and the recommendation for minor revision. The single major comment is addressed point-by-point below.

read point-by-point responses

Referee: [Abstract] Abstract: the stated objectives and configuration are clearly presented, but the manuscript provides no quantitative performance data, error budgets, or verification results to support the claimed sensitivity, imaging resolution, and spectral coverage for TGF detection. This information is load-bearing for evaluating whether the instrument can meet its scientific goals in the ISS environment.

Authors: We agree that quantitative performance metrics strengthen the abstract. The manuscript body contains dedicated sections on the detector configuration, calibration approach, expected sensitivity, angular resolution, spectral coverage, and preliminary error budgets derived from ground testing and simulations. To address the comment directly, we will revise the abstract to incorporate key quantitative figures (e.g., energy range 15 keV–20 MeV, imaging resolution, and TGF detection sensitivity) while keeping the abstract concise. We will also verify that the main text explicitly cross-references the supporting calculations and verification results. revision: yes

Circularity Check

0 steps flagged

No significant circularity; instrument description paper with no derivations

full rationale

This is a factual technical description of the MXGS instrument, its mounting on ISS, subsystems, calibration, and mission objectives. No equations, models, predictions, or quantitative derivations are present. The statement that ASIM is 'the first mission of its kind' is a contextual claim about design goals, not a result obtained by fitting, self-definition, or self-citation chains. The paper is self-contained against external benchmarks as an engineering overview; no load-bearing step reduces to its own inputs.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

No mathematical models, fitted parameters, or new physical entities are introduced; the paper is limited to hardware description and mission objectives.

pith-pipeline@v0.9.0 · 5891 in / 1153 out tokens · 35860 ms · 2026-05-25T16:01:57.117233+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

3 extracted references · 3 canonical work pages

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Cummer, G

Rassoul, S.A. Cummer, G. Lu, R.J. Blakeslee, The rarity of terrestrial gamma-ray ﬂashes. Geophys. Res. Lett. 38,L 0 8 8 0 7( 2 0 1 1 ) .https://doi.org/10.1029/2011GL046875 A. Ursi, C. Guidorzi, M. Marisaldi, D. Sarria, F. Frontera, Terrestrial gamma-ray ﬂashes in the BeppoSAX data archive. J. Atmos. Sol.-Terr. Phys.156,5 0 – 5 6( 2 0 1 7 ) .https://doi.o...

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[1] [1]

Mishieva, P.Y

Klimov, T.M. Mishieva, P.Y . Minaev, V .S. Morozenko, O.V . Morozov, A.S. Posanenko, A.V . Prokhorov, H. Rotkel, Observation of terrestrial gamma-ray ﬂashes in the RELEC space experiment on the Vernov satellite. Cosm. Res. 55(3), 159–168 (2017). https://doi.org/10.1134/S0010952517030017 O. Chanrion, T. Neubert, I.L. Rasmussen, C. Stoltze, D. Tcherniak, N....

work page doi:10.1134/s0010952517030017 2017

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Dietrich, F

Colafrancesco, S. Dietrich, F. Longo, F. Gianotti, A. Rappoldi, M. Trifoglio, A. Trois, Enhanced de- tection of terrestrial gamma-ray ﬂashes by AGILE. Geophys. Res. Lett. (2015).https://doi.org/10.1002/ 2015GL066100 T. Neubert, N. Østgaard, V. Reglero, E. Blanc, O. Chanrion, C.A. Oxborrow, A. Orr, M. Tacconi, O. Hartnack, D.D.V . Bhanderi, The ASIM missio...

work page doi:10.1002/2015gl067064 2015

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Cummer, G

Rassoul, S.A. Cummer, G. Lu, R.J. Blakeslee, The rarity of terrestrial gamma-ray ﬂashes. Geophys. Res. Lett. 38,L 0 8 8 0 7( 2 0 1 1 ) .https://doi.org/10.1029/2011GL046875 A. Ursi, C. Guidorzi, M. Marisaldi, D. Sarria, F. Frontera, Terrestrial gamma-ray ﬂashes in the BeppoSAX data archive. J. Atmos. Sol.-Terr. Phys.156,5 0 – 5 6( 2 0 1 7 ) .https://doi.o...

work page doi:10.1029/2011gl046875 2017