In advance of Fleet Week performances, the U.S. Navy Blue Angels and Team Oracle aerobatics pilot Sean D. Tucker fly over the San Francisco Bay during a photo flight on Thursday, October 5, 2017. (Photo by Noah Berger/AP Photo)

A woman covers her face as a fire burns in the middle of town during an anti-G20 protest on July 7, 2017 in Hamburg, Germany. Authorities are braced for large-scale and disruptive protests as Leaders of the G20 group of nations arrive in Hamburg for the July 7-8 G20 summit. (Photo by Leon Neal/Getty Images)

A couple covered in foam kiss as they take part in the traditional “Raisin Weekend” in the Lower College Lawn, at St Andrews in Scotland, Britain on October 17, 2022. (Photo by Russell Cheyne/Reuters)

Max Gold, 20, of NYC, cruises on his skateboard as thousands gather on the National Mall for the March for Science on Saturday, April 22, 2017, in Washington, DC. Activists and scientists descend on the nation's capital to rally for environmental causes and government policies rooted in scientific research as part of the Earth Day and March for Science rallies. (Photo by Jahi Chikwendiu/The Washington Post)

An Army Sikorsky VH-34s Choctaw helicopter once used to transport President Dwight D. Eisenhower sits in a field at the 309th Aerospace Maintenance and Regeneration Group boneyard Thursday, May 14, 2015 at Davis-Monthan Air Force Base in Tucson, Ariz. President Eisenhower became the first chief executive to be transported by helicopter. Presidents Eisenhower and John F. Kennedy were transported in VH-34 helicopters and VH-34's served as “Army One” from 1958 through 1963. (Photo by Matt York/AP Photo)

Members of the Al-Baraa bin Malek batallion, part of the Free Syria Army's Al-Fatah brigade, duck to the ground as they pull a man (R) who was shot by a sniper twice in the Bustan al-Basha district of the northern city of Aleppo on October 20, 2012. (Photo by Javier Manzano/AFP Photo)

Mario Huettenhofer, chief of the German company 3D Fab, presents his own face as 3d print during the international fairs FabCon 3.D and Rapid.Tech in Erfurt, Germany, Thursday, May 15, 2014. 130 exhibitors from all over the world present the entire world of 3D printing. The trade fairs are accompanied by specialist programs featuring 80 scientists, practitioners and trend analysts from ten countries, who will explain the latest findings, trends and applications for additive processes in industry and for 3D printing in the private sector to newcomers, experts and consumers alike. (Photo by Jens Meyer/AP Photo)

In this photo taken Saturday, January 24, 2015, a child makes a face while having her photo taken with the snow covered slopes of the Nanshan ski resort behind her in Beijing. As Beijing makes a final push in its bid for the 2022 Winter Olympics, Chinese President Xi Jinping says winning the bid will encourage over 300 million Chinese to take up winter sports by 2022, according to state-run Xinhua News agency. (Photo by Ng Han Guan/AP Photo)