Aerial Platform Design Options for a Life-Finding Mission at Venus
, Maxim de Jong 2, Rachana Agrawal 1, Janusz J. Petkowski 3, Archit Arora 1, Sarag J. Saikia 4, Sara Seager 3, James Longuski 1 and on behalf of the Venus Life Finder Mission Team †
Round 1
Reviewer 1 Report
This study is built upon the Venus Life Finder (VLF) mission concepts and details three design options for a Venus balloon mission. It provides crucial numbers for the mission architecture and will help to refine the VLF mission concepts. However, the manuscript lacks precision, and can be improved by providing more details of the design choices and doing a better job at citing relevant references.
First of all, and in all honesty, the sole reason for this study, and the Venus Life Finder missions, is the phosphine detection claims by Greaves et al, which is cited nonchalantly once L136, and implicitly implied in the abstract. The phosphine detection must be clearly explained in the main text, along with the references disputing this claim. This is necessary to provide the recent scientific context that motivates this study.
L15: “For decades”, yet the references are from 2018 and 2021. You could cite Sagan 1961 and Morowitz & Sagan, 1967.
L17: It is quite incongruous to write that the Venus cloud deck is “tenuous”, did you mean something else?
L18: add a reference to historic measurements (e.g., Kraus 1956; Opik 1961; Bonnet et al., 2013 in Understanding the Climate of Venus, etc ...)
L23: Please add a reference to the evolution history of Venus.
L24: Replace “the Soviets” with “the Soviet Union”.
L29: “insertion into the atmosphere”: “entry” would be a better word
L45: Typo: “The Vega, balloons”
L90: “science return is roughly proportional to mass, power, and volume allowances. “ What’s the claim for that? It sounds like a very approximate assertion that would deserve a more rigorous wording. How do you quantify the science return?
L93-99: There is not a word about the selected mission DAVINCI. Its science return for a descent probe is tremendous (not specifically for life detection, though). Could you discuss this?
L128: “The altitudes of scientific interest currently span the entirety of the cloud decks” Which interests exactly? The whole atmosphere is scientifically interesting (you could cite relevant VEXAG goals).
L131 & Figure 1: The UV absorber is usually qualified as “unknown”, not “mysterious”.
How were Figures 5 & 6 obtained? What are the calculations behind these curves?
The instrument configurations in Table 1 are not explained, and are difficult to find in the VLF report (reference [25]). A short rationale of Table 1 will greatly benefit this manuscript. For instance, why are there 3 TLS in the Medium Lite configuration? And why are the configurations named “Habitability”, “Medium”, and “Medium Lite” in Section 4, but the “Medium” and “Medium Lite” terms do not appear in the VLF report? What is “Medium” supposed to mean? I find this word confusing since it is the largest configuration.
In general, there is a gap between this study and the VLF report that could easily be addressed by adding more specific references to the VLF report sections and subsections, and providing simple and brief explanations for the numbers in Table 1.
Author Response
We provide responses to the Reviewer's comments on the Aerospace-1758410 manuscript. Our responses are marked in bold font and the Reviewer's comments are in regular font. Line numbers in our responses correspond to those in the updated manuscript.
Thank you for your thorough review of our manuscript!
This study is built upon the Venus Life Finder (VLF) mission concepts and details three design options for a Venus balloon mission. It provides crucial numbers for the mission architecture and will help to refine the VLF mission concepts. However, the manuscript lacks precision, and can be improved by providing more details of the design choices and doing a better job at citing relevant references.
Noted. We have added additional references and provided more details on the design choices where appropriate.
First of all, and in all honesty, the sole reason for this study, and the Venus Life Finder missions, is the phosphine detection claims by Greaves et al, which is cited nonchalantly once L136, and implicitly implied in the abstract. The phosphine detection must be clearly explained in the main text, along with the references disputing this claim. This is necessary to provide the recent scientific context that motivates this study.
The detection of PH3 is not a main motivation behind the VLF missions. We have reworded the abstract and the relevant text in the introduction to avoid the impression that the development of the VLF missions are solely motivated by the tentative detection of PH3. While the potential detection of PH3 in the Venusian atmosphere is a motivator for a life-finding mission at Venus, the mission would be justifiable and would proceed even if that detection was shown to be erroneous. As noted in lines 137–153, there are many anomalous observations which could be attributed to the presence of life and therefore warrant further investigation. The presence of such anomalies together is the main motivator behind the VLF initiative. We have made that point clearer in the text.
More detailed discussion of the PH3 detection would also require a more detailed discussion of other anomalous observations in the clouds of Venus. We believe that such discussions are beyond the scope of this paper. However, we did provide a citation to an overview paper on the state of the PH3 debate as of 2022.
L15: “For decades”, yet the references are from 2018 and 2021. You could cite Sagan 1961 and Morowitz & Sagan, 1967.
We have included the citation to Sagan 1961 and Morowitz & Sagan, 1967 as suggested.
L17: It is quite incongruous to write that the Venus cloud deck is “tenuous”, did you mean something else?
Perhaps it seems incongruous because the cloud decks span 20 km of altitude and appear opaque from Earth? Nevertheless, the clouds are, in fact, tenuous. As Fimmel writes on page 8 of Pioneer Venus:
“While the clouds of Venus seem opaque from Earth, they are, in fact, very tenuous. Veneras 9 and 10 determined that visibility within the clouds is between 1 and 3 km (0.6 to 1.8 mi.).”
However, since the inclusion of “tenuous” could cause confusion and is not essential to the content of the paper, we have omitted it.
L18: add a reference to historic measurements (e.g., Kraus 1956; Opik 1961; Bonnet et al., 2013 in Understanding the Climate of Venus, etc ...)
We now cite the requested papers in the text.
L23: Please add a reference to the evolution history of Venus.
We thank the reviewer for this suggestion and we now cite the following paper on the evolution and history of Venus: Chassefière, E.; Wieler, R.; Marty, B.; Leblanc, F. The evolution of Venus: Present state of knowledge and future exploration. Planetary and Space Science 2012
L24: Replace “the Soviets” with “the Soviet Union”.
Corrected.
L29: “insertion into the atmosphere”: “entry” would be a better word
We believe that, in this context, the phrase “insertion into the atmosphere” is preferable. Therefore, we decided to leave it as is.
L45: Typo: “The Vega, balloons”
Corrected.
L90: “science return is roughly proportional to mass, power, and volume allowances. “ What’s the claim for that? It sounds like a very approximate assertion that would deserve a more rigorous wording. How do you quantify the science return?
It is difficult to quantify science return. One could say “the more data, the better”, but if the quality of the data is poor, then so will be the science return. Conversely, if only a single measurement is made, but made by a high-quality instrument, the science return suffers as reliability is left in question. A compromise between the two would feature a variety of instruments generating and transmitting large amounts of data.
In all three of the above conceptions, mass, power, and volume requirements increase with science return:
- If we demand more data, then battery (and possibly comms system) size will increase.
- If we demand only a few highly complicated measurements (e.g., characterization of morphological indicators as opposed to measurement of cloud layer water content), we must accommodate more complex—and consequently, larger—instrumentation (e.g., a microscope as opposed to a TLS).
- If we demand an array of instruments, mass, power, and volume requirements increase with the size and required operating time of the array.
The statement that science return is roughly proportional to mass, power, and volume allowances is a qualitative one and reflects a general trend that the size of a science platform increases with the ambition of the science team. We have reworded this sentence to better avoid a quantitative interpretation.
L93-99: There is not a word about the selected mission DAVINCI. Its science return for a descent probe is tremendous (not specifically for life detection, though). Could you discuss this?
We have included a paragraph on the DAVINCI probe in Section 1.
L128: “The altitudes of scientific interest currently span the entirety of the cloud decks” Which interests exactly? The whole atmosphere is scientifically interesting (you could cite relevant VEXAG goals).
The interests are enumerated in lines 140–146 with references cited. To be clear, by “altitudes of scientific interest”, we meant “altitudes of potential astrobiological interest to the VLF team”. We have modified the text to reflect this. On line 149, we refer the reader to Bains et al. and Petkowski et al. for a more in-depth overview of the Venusian anomalies. On line 150, we refer the reader to Petkowski et al. for a discussion on the current status of the Venusian PH3 discovery.
L131 & Figure 1: The UV absorber is usually qualified as “unknown”, not “mysterious”.
Corrected.
How were Figures 5 & 6 obtained? What are the calculations behind these curves?
Calculations are based on the technology and capabilities of Thin Red Line Aerospace Ltd. We have made that point clear in the captions of Figures 5 and 6.
The instrument configurations in Table 1 are not explained, and are difficult to find in the VLF report (reference [25]). A short rationale of Table 1 will greatly benefit this manuscript. For instance, why are there 3 TLS in the Medium Lite configuration?
The rationale of Table 1 is provided on lines 273–274: “The purpose of Table 1 is to better elucidate the designs of the three gondolas as well as the differences between them; namely, those pertaining to instrument accommodation.”
In other words, the table
- shows the reader the number of instruments supported by each gondola design
- explains the different science instrument mass numbers given in the second rows of Tables 2–4
- informs the reader as to the manner in which instruments must be accommodated (e.g., atmospheric inlet, protrusion, or window)
Regarding (3), and to the reviewer’s point, we could (in the paragraphs following Table 1) explicitly connect the type of sealed penetration to the instrument(s) it accommodates. We have modified the manuscript to this effect.
As for the explanations in the report being difficult to find, we have now included references to Section 4 and Appendix C of the VLF Report for discussions on the scientific significance behind the VLF instrument suites.
And why are the configurations named “Habitability”, “Medium”, and “Medium Lite” in Section 4, but the “Medium” and “Medium Lite” terms do not appear in the VLF report? What is “Medium” supposed to mean? I find this word confusing since it is the largest configuration.
This is a good point. The “Habitability”, “Medium”, and “Medium Lite” nomenclature is outdated. These missions are equivalent to the Habitability, VAIHL and VAIHL Lite missions, respectively, found in the VLF Final Report. We have changed the manuscript to reflect this.
In general, there is a gap between this study and the VLF report that could easily be addressed by adding more specific references to the VLF report sections and subsections, and providing simple and brief explanations for the numbers in Table 1.
Agreed. Again, thank you for the thorough review!
Reviewer 2 Report
The article titled "Aerial Platform Design Options for a Life-Finding Mission at
Venus" by Buchanan and collaborators describes the design of a three missions to Venus to analyze the physical and chemical parameters of the Venus' atmosphere by means a low risk (and high scientific returns) baloon architecture. The paper is well organized and written with an explicative introduction.
The Scientific objectives are well delineated. The design of the different missions is also well-outlined considering also innovative solutions. The paper is written in fluent English in a really clear way. I've no major or minor concerns.
From my point of view, the paper could be published as it is.
Author Response
We provide responses to the Reviewer's comments on the Aerospace-1758410 manuscript. Our responses are marked in bold font and the Reviewer's comments are in regular font.
The article titled "Aerial Platform Design Options for a Life-Finding Mission at Venus" by Buchanan and collaborators describes the design of a three missions to Venus to analyze the physical and chemical parameters of the Venus' atmosphere by means a low risk (and high scientific returns) baloon architecture. The paper is well organized and written with an explicative introduction.
The Scientific objectives are well delineated. The design of the different missions is also well-outlined considering also innovative solutions. The paper is written in fluent English in a really clear way. I've no major or minor concerns.
From my point of view, the paper could be published as it is.
We thank the reviewer for accepting our manuscript.
