Planetary protection: an international concern and responsibility

Planetary protection is a set of measures agreed upon at an international level to ensure the protection of scientific investigation during space exploration. As space becomes more accessible with traditional and new actors launching complex and innovative projects that involve robotics (including sample return) and human exploration, we have the responsibility to protect the pristine environments that we explore and our own biosphere. In this sense, the Committee on Space Research (COSPAR) provides the international standard for planetary protection as well as a forum for international consultation. COSPAR has formulated a Planetary Protection Policy with associated requirements for responsible space exploration. Although not legally binding under international law, the standard offered by the Policy with its associated requirements is internationally endorsed along with implementation guidelines supplied for reference in support States’ compliance with Article IX of the United Nations Outer Space Treaty of 1967. Indeed, States parties to the Outer Space Treaty (under Article VI) are responsible for any space activities in their countries, governmental and non-governmental. The main goal of this Policy is to avoid compromising the search for any lifeforms on other celestial bodies and to protect the Earth from a potential threat posed by extraterrestrial samples returned by an interplanetary mission. The COSPAR Planetary Protection Policy has defined five categories, depending on the target and objective of the specific space mission. Associated to these categories are requirements are various degrees of rigor in the contamination control applied. The Policy is assessed regularly and updated with input from new scientific findings and in conjunction with the fast-evolving space exploration milieu. The COSPAR Panel on Planetary Protection (PPP) is a designated international committee composed of scientists, agency representatives and space experts. Its role is to support and revise the COSPAR Policy and its related requirements (https://cosparhq.cnes.fr/scientific-structure/panels/panel-on-planetary-protection-ppp/). The Panel’s activities deal with the individual needs of a space mission while exercising swift care and expertise to ensure sustainable exploration of the Solar System

The COSPAR planetary protection requirements for space missions to Venus

The Committee on Space Research's (COSPAR) Planetary Protection Policy states that all types of missions to Venus are classified as Category II, as the planet has significant research interest relative to the processes of chemical evolution and the origin of life, but there is only a remote chance that terrestrial contamination can proliferate and compromise future investigations. "Remote chance" essentially implies the absence of environments where terrestrial organisms could survive and replicate. Hence, Category II missions only require simplified planetary protection documentation, including a planetary protection plan that outlines the intended or potential impact targets, brief Pre- and Post-launch analyses detailing impact strategies, and a Post-encounter and End-of-Mission Report. These requirements were applied in previous missions and are foreseen for the numerous new international missions planned for the exploration of Venus, which include NASA's VERITAS and DAVINCI missions, and ESA's EnVision mission. There are also several proposed missions including India's Shukrayaan-1, and Russia's Venera-D. These multiple plans for spacecraft coincide with a recent interest within the scientific community regarding the cloud layers of Venus, which have been suggested by some to be habitable environments. The proposed, privately funded, MIT/Rocket Lab Venus Life Finder mission is specifically designed to assess the habitability of the Venusian clouds and to search for signs of life. It includes up to three atmospheric probes, the first one targeting a launch in 2023. The COSPAR Panel on Planetary Protection evaluated scientific data that underpins the planetary protection requirements for Venus and the implications of this on the current policy. The Panel has done a thorough review of the current knowledge of the planet's conditions prevailing in the clouds. Based on the existing literature, we conclude that the environmental conditions within the Venusian clouds are orders of magnitude drier and more acidic than the tolerated survival limits of any known terrestrial extremophile organism. Because of this future orbital, landed or entry probe missions to Venus do not require extra planetary protection measures. This recommendation may be revised in the future if new observations or reanalysis of past data show any significant increment, of orders of magnitude, in the water content and the pH of the cloud layer

Effect of spaceflight on major sleep parameters under both LD (A-D) and DD (E-H) conditions.

<p>The average total sleep time (A, E), average length of sleep episode (C, G), and average sleep episode number (D, H) were calculated based on the <i>Drosophila</i> sleep definition. Green, orange and grey boxes represent data of space flown, control-1, and control 2 flies, respectively. White and black bars stand for daytime and nighttime, grey bar stands for subjective daytime in DD. Statistical significance was determined by two-tailed Student’s t-test with unequal variance. n.s. means no statistically significant differences. Error bars represent SEM.</p

Validation of microarray result for selected genes by QPCR.

<p>(A) <i>tim</i>; (B) <i>vri</i>; (C) <i>mus209</i>; (D) <i>ilp3</i>; (E) <i>kif3c</i>. For each gene, the left plot is the microarray result and the right is the QPCR result. For each graph, the green, orange, and blank lines or histograms represent the space flown group, control-1 group and control-2 group, respectively.</p

Effect of Spaceflight on the Circadian Rhythm, Lifespan and Gene Expression of <i>Drosophila melanogaster</i>

<div><p>Space travelers are reported to experience circadian rhythm disruption during spaceflight. However, how the space environment affects circadian rhythm is yet to be determined. The major focus of this study was to investigate the effect of spaceflight on the <i>Drosophila</i> circadian clock at both the behavioral and molecular level. We used China’s Shenzhou-9 spaceship to carry <i>Drosophila</i>. After 13 days of spaceflight, behavior tests showed that the flies maintained normal locomotor activity rhythm and sleep pattern. The expression level and rhythm of major clock genes were also unaffected. However, expression profiling showed differentially regulated output genes of the circadian clock system between space flown and control flies, suggesting that spaceflight affected the circadian output pathway. We also investigated other physiological effects of spaceflight such as lipid metabolism and lifespan, and searched genes significantly affected by spaceflight using microarray analysis. These results provide new information on the effects of spaceflight on circadian rhythm, lipid metabolism and lifespan. Furthermore, we showed that studying the effect of spaceflight on gene expression using samples collected at different Zeitgeber time could obtain different results, suggesting the importance of appropriate sampling procedures in studies on the effects of spaceflight.</p></div

FaasX analysis showed that Drosophila locomotor activity rhythm was not changed after spaceflight.

<p>Space flown flies exhibited similar locomotor activity rhythm as the two control groups under both LD (A-C) and DD (D-F) conditions. White and black bars stand for daytime and nighttime, grey bar stands for subjective daytime in DD. Group activity was calculated by mean of five days. Two-way ANOVA was applied to the activity data for space flown and control flies at different Zeitgeber time, and the factor of treatment (space flown/control) was not significant by the conventional standard (p < 0.05).</p

Spaceflight affected <i>Drosophila</i> lipid storage.

<p>(A), Space flown flies had similar weights as those of the two control groups. (B), Space flown flies had lower TAG levels compared with those of control-1 flies. (C), Space flown flies had similar body glycogen levels compared with those of control-1 flies. Both TAG and glycogen levels were normalized to the protein level. For each fly group, at least three independent groups of five fly bodies were analyzed. *** indicates significant differences (p<0.001). Statistical significance was determined by two-tailed Student’s t-test with unequal variance.</p

Genes with significantly changed expression level after spaceflight.

<p>Genes with significantly changed expression level after spaceflight.</p