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Planetary Vision 2050 Workshop 2017 (LPI Contrib. No. 1989) 8164.pdf

A ATMOSPHERIC SAMPLE RETURN MISSION CONCEPT: FEASIBILITY AND TECHNOLOGY REQUIREMENTS. E. Shibata1†, Y. Lu2†, A. Pradeepkumar3†, J. A. Cutts‡, and S. J. Saikia4†, [email protected], [email protected], [email protected], [email protected], †School of Aeronautics and Astronautics, Purdue University, 701 W. Stadium Ave., Lafayette, IN, 47907, ‡NASA-Caltech Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA, 91109, james.a.cutts@jpl..gov.

Earth’s “Twin” : Of all the rocky in divergence of Venus and from a geological point the , Venus and Earth come the closest to of view. Although Venus seems to have a young sur- being similar—at first glance. Both are about the same face, tectonic plates are thought not to exist on Venus. size, have approximately the same , and have or- Measuring the outgassing that occurs at the surface, as bits that are close to each other. Similarities end there: well as the composition of the surface, can help us un- whereas Earth has a habitable 1 atm pressure and 15°C derstand how Venus’s core works and how it has average on the surface, Venus has an at- evolved to its current state. Looking into the interac- mosphere at 92 atm and 464°C; Earth has a - tions between the , surface, and interior, the friendly mixture for its atmosphere, while Venus has third goal cements in place how all three have changed corrosive . throughout Venus’s existence. Surface composition may show some record of hydrated minerals, or vola- tiles from the interior. Grabbing Samples from Venus: Future Venus missions should accomplish several of the science goals through in-situ or remote measurements. An at- mospheric sample return would accomplish the first and third goals, while a surface sample would accom- plish the latter two. Although any samples returned would have a relatively small mass compared to in-situ measurements, having a physical sample in a laborato- ry has its advantages [3]. Within a lab setting, more accurate and powerful equipment can be used without having to worry about the mass penalties on the space- Figure 1: Venus photo from the mission. craft. With proper storage, these samples could be used [http://photojournal.jpl.nasa.gov/catalog/PIA00104] again and again with new generations scientists and Venus Science Goals: However, exploring Venus technologies. Taking advantage of nondestructive will help in understanding how our planet has formed. techniques, the same sample can be analyzed multiple Considering the similar volumes and , under- times through a variety of equipment on the ground; an standing how Venus came to be may lead to a better in-situ science rarely has the chance to analyze a understanding of how planets are formed. In the Venus sample that has been analyzed by another instrument. Exploration Analysis Group (VEXAG) Goals, Objec- With samples returned to Earth, any results can be veri- tives, and Investigations study [1], three goals were fied or rejected by reanalyzing the same sample, avoid- identified for future Venus exploration: ing some of the issues that have plagued previous mis-  understanding the atmosphere’s origins and its sions. As seen with lunar samples, any samples re- evolution, as well as the climate history, turned can be retested with new hypotheses, without  determining how the surface and interior having to send another spacecraft to perform more sci- evolved, ence measurements.  and understanding the interior-surface- Price of Thick : Sample returns mis- atmosphere interactions over time, as well as sions from the and were successful, but if liquid water was ever on Venus. to return samples from Venus, technology develop- By measuring the isotopes of nobles gases and , ments and some precursor technology validation mis- the origin of the atmosphere can be found. Additional- sions are essential [4]. These include high-temperature ly, the mid-altitude range of Venus (~55 km) has a ascent balloons that can be inflated at a temperature of pressure of approximately 1 atm and 20°C, which has 460°C, guidance and control technology for a Venus the conditions for habitability and might potentially ascent vehicle that would be launched from a , harbor life forms or evidence of biological processes and thermal control for a Venus ascent vehicle and [2]. The second goal of the VEXAG study looks at the lander that is also compatible with the required sample retrieval activities. Vision 2050 Workshop 2017 (LPI Contrib. No. 1989) 8164.pdf

Atmosphere Samples vs. Surface Samples: Re- lar to the second but uses an airplane to suspend the trieving surface samples from Venus is notoriously VAV and to rendezvous with the balloon carrying sur- difficult due to the technology development required face sample. Figure 2 shows five sample return archi- for the extreme surface conditions. While atmospheric tectures that have been analyzed for Venus. samples can be captured and retrieved with relatively A Venus Atmospheric Sample Return Mission: low cost [5], some of the science goals rely on the re- The goal of this work is to 1) reevaluate the feasibility turn of surface samples. Numerous studies have inves- of Venus sample return mission with state-of-the-art or tigated the feasibility of both atmospheric and surface near-term technologies, and 2) propose a new atmos- sample returns. pheric sample return strategy. The previous Venus Atmospheric Samples. Two types of atmospheric sample return missions have been done with then- sample return missions are considered depending on current state-of-the-art technology. By revisitng these altitude: (1) a single spacecraft can perform a high alti- with modern technologies and other near-term technol- tude flyby over Venus and collect samples from the up- ogies, those mission proposals can be updated and im- per atmosphere; (2) lower altitude flyby uses an addi- proved. Missions are look at the mid-altitudes, where tional element that dives deeper into the atmosphere to conditions for habitability exist, will be concentrated collect gas samples from lower atmosphere and exits on. Revisting the previous architectures proposed, a the atmosphere to rendezvous with a spacecraft return- new Venus atmospheric sample return strategy will be ing to the Earth. The latter concept allows for the col- investigated, which can be done using existing technol- lection of particles and aerosols from the clouds in the ogies or planned in near-term for Earth and other plan- lower altitudes. Another concept [7] considers a single etary applications. One such technology is a Cubesat spacecraft on a free return trajectory and a propulsion launcher. Since Venus and the Earth are similar in size burn of 700 m/s at a periapsis altitude of 110 km to and mass, similar vehicles could be applicable to be compensate for the drag loss. launched from the atmosphere. An Earth launcher de- Surface Samples. Surface sample return missions signed for Cubesats may be useful for raising a Venus would require a surface ascent vehicle. Collecting sur- sample to low-Venus , which is then re- face samples at the aforementioned extreme environ- trieved by an before it propels itself back to ment is complicated enough; the operation becomes Earth. even more demanding when one tries lifting the sam- References: [1] Herrick R. et al. (2016) Goals, ples off the surface. Three approaches of lifting surface Objectives, and Investigations for Venus Exploration samples were studied and compared [6]. The first ap- (VEXAG). [2] Grinspoon D. H. and Bullock M. A proach of using conventional solid rockets has been (2007) American Geophysical Union. [3] Drake M. J. concluded as unfeasible for Venus Ascent Vehicle et al. (1987) , 68. [4] Gershman R. et al. (2000) (VAV) due to the thick atmosphere. A second ap- Aerospace Conference Proceedings. [5] Sweetser T. et proach is to deploy the VAV in the upper atmosphere, al. (1998) AIAA/AAS Astrodynamics Conference. [6] which is suspended on a blimp, and using the blimp to Cutts J. et al. (1999) AIAA Balloon Technology Con- rendezvous the VAV with a balloon that on the ference. [7] Sweetser T. et al. (2003) Acta Astronauti- surface and lifts the sample. The third approach is simi- ca, 52.

Figure 2: Five architectures that have been analyzed. Architecture 1 is the atmospheric skimmer, using a flyby space- craft [5]. Architecture 2 uses a low-altitude probe that collects samples at low velocities [5]. Architecture 3 and 4 use a lander to collect surface samples, with a balloon that brings the VAV (in 3) or just the sample (in 4) to the VAV launch height. Once in orbit, it rendezvous with an orbiting tug [5]-[6]. Architecture 5 has a high-altitude spacecraft burn at the flyby periapsis while collecting samples [7].