Leave it to the country’s space program for a rare bit of political comity. The NASA Transition Authorization Act, signed by President Trump in March after passing both chambers unanimously, allocates $19.5 billion toward NASA for the 2017 fiscal year — a 1 percent increase from 2016. The directive calls upon NASA to expand upon its commercial partnerships for transporting astronauts to the International Space Station, in an effort to direct the agency toward returning to the moon and eventually placing people on Mars.

Yet even this bipartisan measure continues a troublesome pattern: With every new presidential administration, NASA’s mission lurches from one direction to another, hindering the agency’s ability to explore the skies.

The new legislation also calls into question the future of NASA’s Asteroid Redirect Mission, a mission concept that would send a robotic spacecraft to retrieve a boulder from a nearby asteroid and place it in orbit around the moon, where it could be more easily studied. The legislation specifically noted that “the technological and scientific goals of the Asteroid Redirect Mission have not been demonstrated to Congress,’’ suggesting that the proposed mission could be on the chopping block. Although ARM was pitched by NASA as a steppingstone toward eventually reaching Mars, many in Congress as well as the scientific community remain skeptical.

The idea of retrieving asteroids has been discussed for decades. But it has only recently become technically feasible. The ARM mission was developed partly in response to a directive by President Obama in 2010 to send “astronauts to an asteroid for the first time in history’’ by the year 2025, with the landing of humans on Mars to follow in the 2030s. Asteroids provide a rich terrain for industry to extract water and precious metals, while the requisite technology to place humans on an asteroid would pave the way for sending humans to Mars. In fulfillment of Obama’s vision, ARM would provide relatively easy access for astronauts to visit an asteroid and allow for the testing of technology that will eventually be used for sending humans to Mars.

Obama’s asteroid directive followed his elimination of the Constellation program, established by President George W. Bush in 2004 to “return to the moon by 2020, as the launching point for missions beyond.’’ That vision for exploration saw the moon, not asteroids, as the midpoint in the journey to Mars. Yet the Bush administration failed to deliver sufficient funding to sustain the Constellation program, while compounding delays kept it from showing demonstrable success. A 2009 review concluded that completion of the Constellation program would be too costly among NASA’s many missions, so Obama instead shifted priorities toward asteroids.

Science and industry both could benefit from ARM. Asteroids provide an abundance of information on the early era of our solar system’s formation that would contribute to our knowledge of planetary science. Asteroid study also provides greater understanding for how we might deflect an oncoming asteroid from hitting Earth. Asteroids have recently been targeted by private corporations such as Deep Space Industries and Planetary Resources, both of which seek to send mining crews to asteroids in the near future — with claimed potential returns in the trillions of dollars. Any experimental mining techniques developed during ARM could later be used for commercial purposes.

International politics plays into another reason for keeping the asteroid mission. The International Space Station is scheduled to retire in 2020, while the core module of the Chinese large modular space station is planned for launch in 2018. The risk that NASA astronauts could be without access to a near-Earth space station for a decade or longer, while China continues to develop a space presence, provides further justification for building a space station close to Earth. ARM is one possible solution that would allow the United States to maintain an inhabited presence in space.

Yet ARM has plenty of critics. Some are skeptical of the scientific returns and suggest that moving forward could jeopardize existing NASA programs. Advocates of human space colonization, such as Mars Society president Robert Zubrin, have argued that Mars exploration should remain NASA’s priority, with ARM a distraction rather than a steppingstone. Critics in the emerging space mining industry have even expressed reservations about NASA leading a mission that could be placed in their hands.

The fate of ARM, like Constellation and other space programs before it, is symptomatic of a bigger problem. Human space exploration requires unabated commitment to a long-term vision. The multidecade timescales for the development and launch of human space exploration missions far exceed the duration of presidential terms. So the likelihood remains high that shifting politics will continually thwart our pathway to the stars. Realistic ambitions for NASA to send humans to asteroids, Mars, or anywhere else must be coupled with sustained support that remains constant across election cycles and regardless of the party in power.

The future of ARM remains uncertain, and congressional tides may be pulling toward the moon instead. Legislative action without requisite funding cannot place humans in space, but perhaps a suitably funded program could succeed in another lunar landing. Mars still remains the ultimate goal for NASA’s human exploration program, whether by way of asteroids or the moon. But reaching the red planet will require presidential and congressional willingness to stay the course and maintain the long-term visions of their predecessors. Political agreement is a good start, but continuity and commitment are the essential virtues for success in the space age.

Jacob Haqq-Misra is a research scientist with the Blue Marble Space Institute of Science. Follow him on Twitter @haqqmisra