# Balloon Design for Mars, Venus, and Titan Atmospheres
## 1 Introduction
A tool that is capable of simulating and evaluating the performance of different types of balloons, taking into consideration different design options, is one of the main requirements for the balloon deployment. There is a number of tools, e.g., THERMTRAJ [20], the Scientific Balloon Analysis Model (SINBAD) [21], and Balloon Ascent [22] developed by NASA, and ACHAB [23] developed by the Italian Space Agency, which have been extensively used for analysing the performance of balloon flights on Earth. However, none of them can simulate the balloons on other planets as they do not have flexibility to provide multiple environment types, and they have tightly coupled balloon and environment models. Next, Global Aerospace Corporation has developed an advanced balloon performance and analysis tool, called Navajo. This tool aims to advance the state of the art for balloon performance models and assist NASA and commercial balloon designers by providing high-accuracy vertical and horizontal trajectory predictions [24]. It overcomes the drawbacks of other tools, and has other added functionalities, such as simulation of horizontal trajectory, safety analysis capability, and graphical user interface. It is an example of a new, advanced, and modern simulation and analysis tool that enables the development of new balloon and lighter-than-air (LTA) technologies for Earth and planetary applications [25]. However, the full version of Navajo is only available to NASA. For researchers, only the non-Beta test version of the tool is available for purchase. It can simulate zero-pressure balloons within a limited set of environments, and hence it is not useful for detailed analysis of planetary balloons. The Buoyant aerobot design and simulation study (BADS) gives a good insight on planetary aerobots, but the tool itself, as mentioned by the developer, lacks a good stable mathematical core for flight simulation, and hence it is not useful for detailed analysis of planetary balloons [26]. In the last decade, the focus of the ballooning community has been on the improvement of models for flight prediction of stratospheric balloons. [PERSON] et al. [27] studied the influence of infrared radiation on high altitude balloons. [PERSON] [28] did a numerical study on open atmospheric balloon dynamics to gain qualitative understanding of balloon dynamics in the Earth atmosphere. [PERSON] et al. [29] investigated the transient thermal behaviour of stratospheric Earth balloons at float conditions. [PERSON] et al. [30] analysed the effect of thermal model on performance of SP balloons. [PERSON] et al. [31] presented an improved thermal and vertical trajectory model of stratospheric SP balloons. [PERSON] et al. [32] developed a numerical prediction for the trajectories of scientific balloons while considering various uncertainties. Recently, thermal modelling and analysis of airships have attracted the interest of the research community, and a few examples are [33; 34; 35]. The above-mentioned works are insightful for the ballooning community, but before implementing and studying the effects of such models for planetary balloon design, a tool needs to be developed, which can facilitate the study of balloons for bodies with different atmospheres. This paper discusses the development of a tool that is capable of simulating balloons in different environments. The paper focuses on the analysis and synthesis of balloons with different types and shapes for Mars, Venus, and Titan.