{"id":7026,"date":"2023-07-12T14:22:00","date_gmt":"2023-07-12T18:22:00","guid":{"rendered":"https:\/\/new.www.purdue.edu\/newsroom\/?p=7026"},"modified":"2025-07-30T13:25:20","modified_gmt":"2025-07-30T17:25:20","slug":"preventing-traffic-accidents-to-the-moon-and-back","status":"publish","type":"post","link":"https:\/\/www.purdue.edu\/newsroom\/2023\/Q3\/preventing-traffic-accidents-to-the-moon-and-back","title":{"rendered":"Preventing traffic accidents to the moon and back"},"content":{"rendered":"\n
<\/div>\n\n\n

WEST LAFAYETTE, Ind. —<\/p> \n

With dozens of missions<\/a> headed to the space between Earth and the moon over the next 10 years, there\u2019s bound to be traffic.<\/p>\n<\/div>\n\n\n

To prevent those spacecraft from running into each other, Purdue University engineer Carolin Frueh<\/a> is investigating how to observe and keep track of all human-made objects and predict the impact of their potential damage in this Earth-moon neighborhood, called the cislunar region. <\/p>\n\n\n\n

According to Frueh, a Purdue associate professor of aeronautics and astronautics<\/a>, the reality is that solutions for space traffic in the cislunar region will be moving targets. The methods she is developing are intended to adapt to this region as traffic changes.<\/p>\n\n\n\n

\u201cThere will never actually be a final answer to a space traffic management problem because as the commercial sector grows and the capabilities and types of vehicles that you have change, the problem will evolve, too,\u201d she said. \u201cSo when we think about the techniques that we want to use, we also have to be sure that what we have in mind can evolve over time.\u201d<\/p>\n\n\n\n

The economic potential of cislunar space is estimated to be more than $30 billion<\/a> over a 20-year period, taking into account government investment, demand for space telecommunications services and other factors.<\/p>\n\n\n\n

At 238,900 miles, the distance between the Earth and the moon is 18 times longer than the Great Wall of China. That might seem like enough room for spacecraft to move around without hitting each other, but the cislunar region is far less understood than near-Earth orbits, which extend 24,000 miles beyond Earth\u2019s surface up to a \u201csweet spot\u201d called the geosynchronous region that enables satellites to keep pace with Earth\u2019s rotation. Near-Earth orbits are home to most satellites. Famous residents of that area include the Hubble Space Telescope and International Space Station.<\/p>\n\n\n\n

Even with more knowledge of near-Earth orbits, approximately 130 million pieces of space debris<\/a> surround Earth. Much of this debris has broken off satellites that exploded or collided with other objects. Debris has already made it to the moon: A rogue rocket booster crashed onto the lunar surface last March<\/a>.<\/p>\n\n\n\n

\"\"
This animation shows human-made space objects cataloged by the U.S. Space Force. The red objects are in near-Earth orbits. The green objects are in the cislunar region. (Purdue University image\/Carolin Frueh) <\/figcaption><\/figure>\n\n\n\n

To address forthcoming traffic in cislunar space, Frueh has been pulling from her research on how spacecraft become debris<\/a>. She works with space agencies around the world to improve databases of space objects.<\/p>\n\n\n\n

Doing the same for cislunar space will be difficult without being able to see as much of that larger region. For near-Earth orbits, telescopes in space and to a limited extent telescopes on Earth are among the \u201ctraffic cameras\u201d for satellites. But there aren\u2019t any telescopes in the cislunar region because there isn\u2019t much satellite activity to observe yet. Space-based telescopes would be better at tracking cislunar satellites when more of them populate that area because ground-based telescopes can only detect a satellite of interest in cislunar space if the satellite, moon and Earth are aligned exactly right.<\/p>\n\n\n\n

Together with her student, Surabhi Bhadauria, Frueh is developing a way to create \u201cvisibility maps<\/a>\u201d that would show the best regions telescopes should use to find and track human-made objects in cislunar space \u2014 including active satellites, dead satellites and fragments of satellites.<\/p>\n\n\n\n

Compared to other approaches, these maps better address a big challenge with surveilling the cislunar region: space is always changing. The constantly moving positions of the Earth, moon and sun affect what a telescope observes at any given moment and which orbits it can use to see spacecraft well. Current mapping methods must re-run a model for each condition that would affect a telescope\u2019s orbit and overall viewing geometry at each instance in time, which is computationally intensive.<\/p>\n\n\n\n

\"\"
\u201cVisibility maps\u201d could show where to put telescopes in cislunar space to improve detection and surveillance of human-made objects, helping to prevent satellite collisions. This visibility map considers all the constraints that would affect the orbits telescopes should use to capture as much of a region as possible over a 30-day period. The map shows regions of less visibility (pink) and higher visibility (yellow) independent of the viewing direction. (Purdue University image\/Surabhi Bhadauria and Carolin Frueh)<\/figcaption><\/figure>\n\n\n\n

Frueh\u2019s visibility maps run on models that more quickly and comprehensively indicate where telescopes should go to observe as much of the cislunar region as possible. The maps allow for seeing more of a region by averaging out all the orbits a telescope might use rather than integrating each orbit change over time like other mapping methods have to do. Frueh\u2019s method also doesn\u2019t require any additional computational time to show which satellites can be observed under which conditions from various locations.<\/p>\n\n\n\n

\u201cIt\u2019s like planning a road trip. Right now, we have identified points of interest in the cislunar region to observe with telescopes, but we haven\u2019t found the route yet for putting the telescopes there,\u201d Frueh said.<\/p>\n\n\n\n

Even when telescopes are eventually put into the cislunar region, satellites will likely just look like white dots or streaks in the images these telescopes capture. But Frueh is used to gleaning meaningful information from these shapes in telescope images of satellites in near-Earth orbits. She\u2019s working on a method that would allow researchers and mission planners to discern the orbits that a satellite is using to do its mission. The method would be designed to work under a range of scenarios \u2013 even when very little is known about the satellite.<\/p>\n\n\n\n

Since it\u2019s inevitable that traffic accidents will happen in cislunar space, Frueh also is thinking ahead on how to estimate the damage an accident could cause. If a collision or explosion happens, where do all the pieces end up?<\/p>\n\n\n\n

Her research indicates that pieces from a fragmented satellite can travel long distances in a relatively short amount of time. She and her student, Ariel Black, recently presented a study at the 2023 AAS\/AIAA Space Flight Mechanics Meeting<\/a> showing these pieces can travel effortlessly all the way back to Earth from deeper into cislunar space.<\/p>\n\n\n\n

\"\"
In this chart, fragments of an exploded spacecraft near the moon are predicted to disperse millions of miles away within just a month\u2019s time. Each color indicates how far fragments could spread from one explosion point on an orbit of the Lyapunov orbit family around a location called the second Lagrange “L2” point. These orbits are being considered for cislunar missions. On each orbit, the explosion point is assumed to be in line with the Earth and moon. (Purdue University image\/Ariel Black and Carolin Frueh)<\/figcaption><\/figure>\n\n\n\n

\u201cWe are laying the foundations that we believe will shape how space traffic management problems are addressed in the cislunar region,\u201d Frueh said.<\/p>\n\n\n\n

About Purdue University<\/strong><\/h2>\n\n\n\n

Purdue University is a public research institution with excellence at scale. Ranked among top 10 public universities (Times Higher Education\/Wall Street Journal and QS), with two colleges in the top 4 in the United States (U.S. News & World Report), Purdue discovers and disseminates knowledge with a quality and at a scale second to none. More than 105,000 students study at Purdue across modalities and locations, with 50,000 in person on the West Lafayette campus. Committed to affordability and accessibility, Purdue\u2019s main campus has frozen tuition 12 years in a row. See how Purdue never stops in the persistent pursuit of the next giant leap, including its first comprehensive urban campus in Indianapolis, the new Mitchell E. Daniels, Jr. School of Business, and Purdue Innovates, at https:\/\/stories.purdue.edu<\/a>.<\/p>\n\n\n

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\n Writer\/Media contact:<\/strong>\u00a0Kayla Albert, 765-494-2432,\u00a0wiles5@purdue.edu<\/a>

Papers:<\/strong>

Optical observation regions in cislunar space using the bi-circular restricted four body problem geometry<\/em>
The paper is available online on the site of the\u00a0Advanced Maui Optical and Space Surveillance Technologies Conference.<\/a>

I<\/em>nvestigation of fragmentation events in the cislunar domain<\/em>
This study was presented at the\u00a02023 AAS\/AIAA Space Flight Mechanics Meeting<\/a>.\u00a0Please contact Kayla Albert at\u00a0wiles5@purdue.edu<\/a>\u00a0or 765-494-2432 for a copy of the paper. <\/p>\n <\/div>\n

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Note to journalists:<\/p>\n

\n Photos of Frueh and her cislunar space research<\/a>, along with\u00a0b-roll of Purdue University\u2019s campus<\/a>,\u00a0are available via Google Drive.\u00a0Sound bites<\/a>\u00a0of Frueh discussing her work and expertise are accessible to media who have an Associated Press subscription. <\/p>\n <\/div>\n <\/div>\n <\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

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