![Lagrange points are positions in space where the gravitational forces of a two-body system like the Sun and Earth produce enhanced regions of attraction and repulsion.](https://cdn.arstechnica.net/wp-content/uploads/2023/12/Lagrange-800x683.jpg)
NASA
A bipartisan committee within the US House of Representatives recently issued a report on the economic and technological competition between america and China and offered nearly 150 recommendations to “fundamentally reset” the connection.
The report followed a year-long study of the competition between the countries since China’s entry into the World Trade Organization in 2001.
“The Chinese Communist Party has pursued a multi-decade campaign of economic aggression against america and its allies within the name of strategically decoupling the People’s Republic of China from the worldwide economy, making the PRC less depending on america in critical sectors, while making america more depending on (China),” the report states.
This initiative was a bipartisan effort led by US Reps. Mike Gallagher (R-Wis.) and Raja Krishnamoorthi (D-Ailing.). In light of the concerns raised throughout the report, it sets out recommendations that can allow america to “chart a brand new path that puts its national security, economic security, and values” on the front and center of its relationship with China.
The recommendations cover a broad range of domains, but one suggestion on space was particularly notable. It involves locations where gravity is fairly stable, referred to as Lagrange points.
All roads result in L2
The precise language within the report is that this: “Fund NASA’s and the Department of Defense’s programs which might be critical to countering the CCP’s malign ambitions in space, including by ensuring america is the primary country to permanently station assets in any respect Lagrange Points. The CCP understands well the necessity for space-based operations and is developing formidable space capabilities to challenge US dominance on this domain.”
So what are the Lagrange points, and why are they the brand new high ground in space? NASA has a great primer here. But the fundamental gist is that there are five points within the Earth-Sun system where the gravitational pull of the 2 bodies is effectively canceled out. Of the five Lagrange points, three are unstable, and two are stable. The unstable Lagrange points are L1, L2, and L3. The stable Lagrange points are L4 and L5.
Each of those Lagrange points has some strategic value, but some greater than others. To know how, Ars spoke with Laura Duffy, an area systems engineer for Canyon Consulting who served five years within the Air Force and is an authority in astrodynamics.
The primary two points, L1 and L2, are particularly useful due to their proximity to the Moon. Although they usually are not entirely gravitationally stable, a spacecraft can fly a “halo” orbit around these locations and maintain their position with minimal propellant.
“L2 is specifically vital due to its visibility to the far side of the Moon,” Duffy said. “We cannot see that from the Earth, and China is headed there.”
She is referring to the Queqiao relay satellite, which China launched right into a halo orbit around L2 five years ago. It relayed communications from a lander on the far side of the Moon. This spacecraft, Chang’e 4, was the primary vehicle humans have soft landed on the far side of the Moon. So China already has a demonstrated advantage on this area and plans to further it.
Duffy and a colleague at Canyon Consulting, James Lake, wrote in regards to the strategic importance of China’s efforts at L2 within the Space Force Journal two years ago. “China’s successful mission to the non-Earth facing side of the Moon has drawn probably the most concern from a military perspective due to lack of monitoring capabilities on the far side of the Moon,” they wrote.
Keeping a watchful eye on the Moon
Another excuse why L1 and L2 are strategically worthwhile is that, as a result of the character of orbital dynamics, they’re excellent way stations. Assets positioned there, Duffy explained, require little or no orbital energy—or delta V—to succeed in anywhere else within the Earth-Moon system. In other words, if you happen to desired to rapidly reply to some variety of activity in cislunar space, these could be good locations to preposition assets.
Two other Lagrange points, L4 and L5, are also vital. While they’re quite distant, 60 degrees ahead of and behind the Earth in its 360-degree orbit across the Sun, they’re stable. Furthermore, they’ve strategic value for position, navigation, and timing services in cislunar space because they’re farther out and might take a look at the system as a complete.
The House report provides no detailed details about what sorts of assets america and its allies should stage on the Lagrange points. However it seems clear that a primary step will involve satellites that provide higher situational awareness to watch what China and other actors are doing in cislunar space.
“We’re in one other space race back to the Moon, and this time it’s with China,” Duffy said. “We would like to be first because we wish to set the norms.”