There is an ongoing discussion about the participation of women in science and particularly astronomy. Demographic data from NASA's robotic planetary spacecraft missions show women scientists to be consistently under-represented.
Many sciences have attempted to close the gender and racial gaps in their communities1,2. These same groups may attempt to measure those gaps by examining the success rates of white women and people of colour in their fields through, for instance, accumulating population statistics or determining publication counts. However, such numbers may mask the persistent effects of seniority and the accumulation of praise and accolades within the field3, as well as exposure to career-making opportunities. Just as assessing citation counts demonstrates a bias against women scientists4, there are other indications of field centrality and career success that we can turn to in examining the fate of women and members of one or more under-represented groups in the sciences.
For instance, planetary scientists often not only work in traditional academic roles, but also as civil servants in governmental agencies and in soft-money positions at research institutions. As such their institutional goals vary in terms of publication requirements and grant acquisition — two classic ways of determining ‘success’ in a community. However, regardless of their job, many planetary scientists aspire to involvement in spacecraft mission science teams. Membership in such a team offers brand new data, financial security, and a sense of awe and exploration. It can lead to a cascade of opportunities from conference and public presentations, to membership in subsequent mission teams, and prestige in the community. As such, in order to determine the persistence or change in the gender gap in planetary science, we use spacecraft team participation as a measure of success.
Along with a team of volunteers, we found lists of original science team members for 26 NASA robotic planetary missions during a period of 41 years5,6. The list included only principal investigators (PIs) and co-investigators and did not include project management teams, engineers, graduate students, postdocs, or team affiliates. The lists were found on team webpages, internet archives and published articles and fact sheets. For each list, we determined the year the team was selected and, for each name, the person's gender and affiliation at time of selection. At this time, we are unaware of investigators in this study who do not identify on the gender binary, so we limited our gender determinations to male and female. While we collected data on all investigators, the plots and results here consider only investigators at US institutions.
In our study we were attuned to both absolute numbers and proportions. Because NASA missions vary in size and complexity — from small Discovery and New Frontiers teams, to Flagship missions that may employ hundreds of scientists — team size is an important factor in determining proportionality, but missions with small team sizes and higher proportions of women may still represent a small number of women in key roles.
Figure 1 shows our primary results. The pre-2000 average is 5.7% women on spacecraft teams. Since 2000, the percentage of women has remained flat at 15.8%. When we fit a line to our data over that time period, we get a very small negative slope. Due to the scatter in the data, we do not believe this linear fit to be significant, only illustrative that there has been no growth in the percentage of women on spacecraft science teams in the past ∼16 years. Groups with 15% participation of a minority population result in tokenist dynamics, which set in motion “self-perpetuating cycles that reinforce the low numbers”7.
To determine whether these numbers and proportions represent changes in the composition of the field, Fig. 2 shows the percentage of women in planetary science overall. There is no single measurement for this number so we used the 2011 planetary workforce survey (red triangle), the American Astronomical Society's Division of Planetary Science (DPS) surveys (blue squares; although not all planetary scientists are members of DPS), and the most detailed survey of women in astronomy by the Committee on the Status of Women in Astronomy (CSWA). The green diamonds show the percentage of women non-students in the CSWA survey. According to these surveys, the percentage of women in the field reached ∼15% in the late 1990s and has increased since then to more than 25% in 2013. The line shows a linear fit to the data and predicts that the field will reach parity in 2049. If the trend continues, the percentage of women in 2017 should be just under 30%. Only four of the 26 (15%) missions shown in Fig. 1 are above the line on Fig. 2, demonstrating that professional women in the field are still proportionally under-represented on mission teams
PIs typically form spacecraft or instrument teams at or before a mission's inception, but in the 2000s NASA created participating scientist (PS) and guest investigator (GI) programs to provide an influx of fresh personnel onto a mission's science team. These programs are solicited though the annual NASA Research Opportunities in Earth and Space Science (ROSES) call and the resulting selections are available on the NASA Solicitation and Proposal Integrated Review and Evaluation System (NSPIRES). While PS and GI programs select people through a proposal and review process using a panel of peer scientists, the original teams are, in most cases, selected by a single principal scientist. Figure 3 shows how these programs affect the make-up of spacecraft science teams. We examined the names of the selected scientists and determined their gender in the same way as for the original teams. Figure 3 shows results for several missions, with a green bar indicating the number of women in the selection and the purple bar the number of men.
The average percentage of women selected in PS and GI programs is substantially higher than the originally selected teams (24.2%), which roughly corresponds to the percentage of women in the field circa 2008 (Fig. 2). By comparing the percentages of women on the original team (leftmost bars) and composite team (rightmost bars), we find that, of the teams shown, only the Mars Curiosity mission substantially increased its percentage of women participation (from 13.5% to 25%). This is because the two PS calls for this team resulted in substantial additions to the team. However, in most cases, even with the additional members selected through PS and GI programs, the resulting percentage of women on missions remained well below that in the field.
While the percentage of women in planetary science appears to be increasing, their representation on spacecraft science teams has not been commensurate, demonstrating that the planetary science community is not benefiting from the expertise of many qualified women scientists. So, how do we increase their participation? A clue may lie in the fact that PS and GI programs are doing a demonstrably better job at selecting women than the original science teams.
NASA has recently begun collecting demographic information through its grant application portal, NSPIRES. It will be informative to compare the percentage of women applying for NASA programs to the percentage selected. Furthermore, the latest announcement of opportunity for a robotic spacecraft science team in the New Frontiers program and the 2017 NASA ROSES call for proposals, adds this sentence: “NASA recognizes and supports the benefits of having diverse and inclusive scientific, engineering, and technology communities and fully expects that such values will be reflected in the composition of all proposal teams as well as peer review panels (science, engineering, and technology), science definition teams, and mission and instrument teams.” Assuming this directive is actively pursued in the selection/award process, it will hopefully result in an increase in the participation of women on the proposal teams.
While our study concentrated on gender, future studies should also consider race and membership in other under-represented groups. The planetary science workforce survey11 found that 87% of planetary scientists identified as white, substantially above the percentage of the US population (64% in 2010). Anecdotal data suggest that white scientists are similarly over-represented on spacecraft mission science teams and that white women are over-represented compared to women of colour. The planetary science community and robotic spacecraft mission teams have a long way to go to become a diverse and inclusive community, but new data collection and policies are a small positive step in the right direction.