Mission Architecture to Characterize Habitability of Venus Cloud Layers via an Aerial Platform

Round 1

Reviewer 1 Report

I read the exciting manuscript in one go. I think it is a solid mission study ready for publishing. Thanks! 

 

The manuscript “Mission Architecture to Characterize Habitability of Venus Cloud Layers via an Aerial Platform” by Agrawal et al. presents a novel mission design to explore the clouds of Venus using a balloon. Co-authors of the manuscript have presented the science case for Venus clouds in a range of papers and studies, and the most recent findings are summarized by the manuscript under review. Sending a mission to take actual measurements in Venusian clouds is the next logical step. In the current day of space technology, a Venus balloon mission includes a set of novelties which the team will have to address and that are indicated in the mission study paper. First, only Soviets have sent a balloon to a planetary body. The engineering solutions of the Soviet VeGa mission can serve as inspiration but entirely new development is necessary, which requires to make a mission architecture, as presented by the manuscript. Second, the proposed Venus balloon is part of a larger mission design, setting up constrains and opportunities for the balloon. Third, the VLF team bypasses the typical finding sources, such as slow-moving and conservative agency mission proposals, and cooperates with Breakthrough Initiatives instead.
The mission architecture itself is well designed, studied and presented in the manuscript. The facts and figures are well-selected (probably the team has an order of magnitude more analysis and results). The team designs the mission starting with science goals and requirements before setting up requirements for instruments, which is all common sense in the space mission design (see JPL’s Concept Maturity Levels, for example). The mission design includes all necessary details to achieve the science objectives – most importantly, when and what kind of measurements will be taken. If successful, this and other VLF missions would be ground and sky breaking in the search for life, Venus research and planetary science and space tech in general. The reviewed manuscript is a solid platform on which to develop the instruments, the spacecraft and the concept of operations. I wish all the best to VLF team and thank you for the inspiration. The paper is excellent and accepted on my side without a revision.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

I enjoyed reading the paper, it's one of the best I have read in the last year. I'm normally quite critical when I have to referee papers. My judgment is mainly "major revisions" or "reject", but in this case it's "accept after very minor revisions".

The paper is a typical mission concept study, done by experts for future mission designs. I assume that this study was submitted for a NASA call for medium missions. Such studies are generally of high quality as otherwise the chances to get the mission are non-existent. Such studies for mission concepts should be published for future references if such a mission becomes feasible in the near or far future. The paper is concise, all figures are needed, it's interesting to read, and it's clear. Of course, I cannot check all calculations made, but the whole paper makes sense and is complete. If I want to find any fault with this paper, then one could say that the phosphine which is mentioned in the paper is most probably just a wrong interpretation of data and that not only the first paper should be cited, but also the papers, which question this first paper. Another thing is that part of the introduction is copy-paste from a report which is on arXiv. But, the authors are at least partly the same as in the present paper, it's referenced (their reference [10]), and it's not published in a journal.

This paper is original, and it is very well written and interesting to read. 

The only comment I have is probably a typo: line 378: the benign environment is below and not above 150°C, 6 bar.

Author Response

Please see the attachment.

Author Response File: Author Response.docx