Why can't active NASA astronauts endorse US presidential candidates?

Today is election day. All U.S. citizens, whether at home or abroad, are encouraged to vote today — even those citizens in space.

Yes, NASA astronauts on the International Space Station (ISS) or on other spaceflight missions have voted in U.S. elections throughout the agency's history, and this year is no exception. The four NASA astronauts currently on the ISS have either already voted or are able to vote through casting special absentee ballots using NASA's Near Space Network network of satellites and ground stations. And because most NASA astronauts live in Texas near the agency's Johnson Space Center in Houston, Texas passed a law in 1997 officially allowing astronauts to vote from space, according to NASA.

But while active astronauts can vote from space, there are still restrictions on the types of political activities that they and other NASA employees are allowed to engage in. Chief among those prohibitions is the endorsement of a specific political candidate or political party.

When asked for comment about why agency astronauts cannot endorse specific candidates, a NASA spokesperson told Space.com via email that "NASA astronauts are federal employees, and are prohibited by the Hatch Act from using their official titles or positions while engaged in partisan political activity."

That code, the Hatch Act (5 U.S.C. § 7321-7326), specifically prohibits federal employees such as NASA astronauts from using their positions "for the purpose of interfering with or affecting the result of an election."

According to a memo dated Oct. 8, 2004 sent from NASA's Office of the General Counsel, the Hatch Act specifically prohibits agency employees such as astronauts from engaging in political activity while on duty, on government property, while "wearing a uniform or other similar item that identifies NASA as the employing agency," or while "using a government vehicle," which would presumably include the International Space Station and other spacecraft.

Nevertheless, the four NASA astronauts on board the ISS took to social media today to show their patriotism by encouraging Americans to get out and vote:

However, the Hatch Act does not mean that NASA employees and astronauts have to avoid mentioning politics or political issues altogether. In another memo, dated August 2020, NASA's Office of the General Counsel noted that employees may still "express their opinions about current events and matters of public interest at work so long as their actions are not considered political activity."

All this is to say that, while NASA astronauts are free to voice their opinions on specific issues or legislation, they cannot endorse a particular candidate or political party. "Partisan political activity is distinct from discussions of current events, policy issues, and matters of public interest," the 2020 memo points out.

When two active NASA astronauts, Anne McClain and Jessica Meir, posted a selfie of themselves voting on social media in late October 2024, some commenters suggested that the duo were endorsing Vice President Kamala Harris, the Democratic nominee for president. Such critics cited McClain and Meir's "I Voted" stickers, which featured the text "harrisvotes.com" along the bottom.

However, that text does not refer to Kamala Harris: The stickers were produced by Harris County in Texas, the county in which Houston and NASA's Johnson Space Center are found. Because the astronauts were merely voting, and not endorsing a specific candidate, their social media post does not appear to violate U.S. federal code.

But that's not to say that politics and NASA spaceflight don't sometimes overlap. In 2020, President Donald Trump's campaign released a 2.5-minute video titled "Make Space Great Again" that drew widespread criticism for politicizing the space agency.

The ad used footage of the 2020 launch of the SpaceX Demo-2 mission, the first orbital human spaceflight to launch from the United States since the 2011 retirement of the space shuttle fleet, to seemingly make a case for Trump's candidacy that year. But as many pointed out, NASA's Commercial Crew Program began in 2010 during the presidency of Barack Obama.

We've also seen plenty of former astronauts formally endorse candidates after their retirement. Just last month, Apollo 11 astronaut Buzz Aldrin, the second person ever to step foot on the moon, endorsed Republican nominee Donald Trump for his 2024 presidential bid. Other former NASA spaceflyers, such as Jose Hernandez, Garrett Reisman and Senator Mark Kelly (D-Ariz.), took to social media this year to endorse Harris.

Editor's note: This story was updated at 4 p.m. ET (2000 GMT) to include comment from NASA.