Review Reports

Round 1

Reviewer 1 Report

The Conclusions section has two issues that need to be addressed.  The JAXA MMX mission is suggested as a candidate to fly the MIRORES instrument.  The payload for this mission has already been selected, with a planned launch in 2024, so it cannot be considered a candidate.  Second, it's now mid 2022.  If "creation and testing of a prototype" has already begun, this should be described.  Otherwise, "2021" should be changed accordingly.

Author Response

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Reviewer 2 Report

I still have some concerns on the instrument design presented in this paper. However, I greatly appreciate the effort the authors have done to improve the design and the paper. If the authors plan to propose this design for a space mission, I strongly suggest them to check the radiometric performances. They say that SNR is 1.6 but I guess it is much lower. This is linked to the system F-number which is still very high. They mention that the detector can be cooled but, as I understand, it is a pyroelectric detector which works only at room temperature and there is no improvement in sensitivity by lowering its temperature. The same for the collimators. Why are they cooled? Cooling telescope's parts make sense if you are using a detector which is shot noise limited and doing so you increase the SNR. In your case, you are using a detector which is background noise limited and there will be no benefit by cooling the collimators. The only reason I see is to stabilize the instrument background and simplify the in-flight radiometric calibration. Please clarify this.

Author Response

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Reviewer 3 Report

The article describes the potential of a new relatively inexpensive instrument (MIRORES - Martian far-IR ORE Spectrometer), designed to search for large and medium-sized sulfide ores (pyrite, chalcopyrite, marcasite) at remote sensing of the Martian surfaces in the far infrared range. There is no doubt that any data on ores, incl. sulfide, containing large amount of noble (Au, Ag), base (Cu, Pb, Zn, Sn, Co, Ni, etc.), and occasionally in platinum group (PGM) metals will be of great importance for the subsequent exploration of the Mars.

The proposed spectral characteristics of MIRORES are compared with other instruments previously operating on Mars: Compact Reconnaissance Imaging Spectrometer for Mars (CRISM; operating in a wavelength range of 0.4–3.9 μm) launched in 2005 on the Mars Reconnaissance Orbiter (MRO), the OMEGA (0.4–5.1 μm), and the Planetary Fourier Spectrometer (PFS; 1.3–45 μm) launched on Mars Express (MEX) in 2003, and Thermal Emission Spectrometer (TES; 0.3–2.9 and 6–50 μm) launched on Mars Global Surveyor in 1996. PFS/MEX and TES/MGS cover the FIR spectral range at spatial resolution of ~12 km and ~3 km, respectively, which not sufficient to search for ore deposits cover areas up to hundreds of meters). The MIRORES instrument is planned to measure 32 x 32 x 42 cm and mass <10 kg to common microsatellite requirements. The authors believe that solid and disseminated sulfide ores containing 10–20% pyrite and probably also their stockworks, up to 33–66 m² on a surface of ~330 m² can be detected on Mars with MIRORES.

One of the main limitations of the instrument will be the ubiquitous distribution of dust and loose sediments, which cover outcrops of Martian bedrock, and sulfide-bearing ones. In this regard, I would recommend to the authors simulated mass absorption coefficients for mineral mixtures not only for olivine-phyric shergottite + pyrite (Figure 6), but also for the average compositions of Martian dust + pyrite.

Author Response

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Reviewer 4 Report

The topic is very interesting and the concept and design of martian far-IR ORE spectrometer should have broad readers in space science and technology. For future mars exploration and ISRU, ore-forming minerals survey and detection is essentially important. As previous payloads operating on mars (e.g. CRISM) can not  detect sulfides, the most important materials containing Au, Ag, Cu, Pb, Zn, etc metals. They are the self-sustainment for future mars colonies. The proposed MIRORES can solve this problem. Althouth there are some challenges when contuct global survey as it only have small field of view, a pre-selceted ROI will help to solve this problem. The paper was well written and orgnized, match well with the journal. 

Author Response

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