Satellite Megaconstellations

When connectivity in orbit starts to reshape astronomy and sustainability

Date: December 21, 2025
An Ursa Cortex Blog by Rushil Sharan

One of the biggest shifts happening in space right now is the rapid growth of satellites in low Earth orbit (LEO), driven largely by broadband megaconstellations like Starlink. More satellites can mean better global connectivity and lower latency internet access around the world. But it also means more space traffic, higher collision risk, and growing concerns about what this does to space-based astronomy.

In this post, we break down two developments: a major 2025 Nature study warning that megaconstellations could contaminate a large fraction of space telescope images, and Starlink’s continued deployment pace that shows how quickly the orbital environment is changing.

Why are megaconstellations growing so fast?

Megaconstellations are large fleets of satellites designed to provide continuous coverage for communications and broadband. Because these satellites orbit relatively close to Earth, they can reduce signal delay compared to systems in much higher orbits. The tradeoff is scale: to provide reliable global coverage, you need a lot of satellites, and you need to keep replenishing them over time.

That scale is what changes the game. As the population in LEO grows, orbital operations become more complex for everyone. Tracking becomes harder. Conjunction alerts increase. And the odds that a satellite crosses the field of view of a telescope during a long exposure goes up.

A 2025 Nature study warns of major impacts on space-based astronomy

A peer-reviewed study published in Nature (Borlaff et al., 2025) modeled how proposed satellite megaconstellations could affect space telescopes. The results were striking: if planned constellations scale to their proposed totals, the authors project that satellite trails could appear in roughly one-third of Hubble exposures and in more than 96% of exposures for some upcoming missions (including SPHEREx, ARRAKIHS, and China’s Xuntian telescope). (Nature study)

More importantly, the study highlights a problem that does not have an easy “software fix.” Once a bright trail crosses an exposure, it can permanently overwrite information from faint objects behind it. Masking a trail can remove the obvious streak, but it cannot reliably recreate the missing data beneath the streak, especially when the goal is precise measurement. (Nature News)

Bottom line: as megaconstellations scale, satellite trails risk becoming a routine condition for space telescopes, not an occasional disruption.

Starlink’s 2025 launch cadence shows how quickly the environment is changing

SpaceX has continued deploying Starlink throughout 2025, with Falcon 9 launches frequently adding dozens of satellites at a time. For example, Spaceflight Now reported a December 2025 mission that deployed another batch of 29 Starlink satellites. (Spaceflight Now coverage)

As of December 2025, Space.com estimated Starlink has 9,357 satellites in orbit (with 9,347 operational). The same source notes Starlink has referenced long-term plans as high as 42,000 satellites. (Space.com Starlink overview)

This matters because system-level risk scales with population. Even if each individual satellite is well-designed, adding thousands of objects increases the number of close approaches, the number of collision-avoidance decisions, and the overall burden on tracking and coordination across operators.

STEM spotlight: why satellite trails are hard to “edit out”

Space telescopes often take long exposures to capture faint light from distant objects. During that exposure, a satellite can cross the telescope’s field of view and reflect sunlight into the detector. That reflected sunlight appears as a bright streak.

Software can sometimes detect the streak and mask it, but masking does not restore the missing information. If a trail crosses a faint galaxy, then the photons from that galaxy in that region were never recorded correctly. In some cases you can re-observe the same patch of sky, but telescope time is limited, and many missions depend on carefully planned observation schedules.

What comes next: balancing access, science, and sustainability

Megaconstellations can deliver real value, including improved connectivity in remote regions and resilience during disasters. At the same time, astronomy is a shared global scientific resource, and LEO is a shared environment.

Mitigation is possible, but it requires coordination. That can include reducing satellite brightness, improving orbital transparency (so observatories can plan around predicted trails), strengthening debris mitigation and end-of-life disposal, and establishing clearer norms for how we manage crowded orbital shells. Ultimately, this is a systems engineering problem: maximizing benefit while minimizing harm across a shared infrastructure.

For Further Reading

• Borlaff et al. (2025), Nature: “Satellite megaconstellations will threaten space-based astronomy”
• Phys.org summary of the study and implications (Dec 2025)
• Nature News: “Satellite swarms set to photobomb more than 95% of some telescopes’ images” (Dec 2025)
• Space.com: Starlink facts, tracking, and astronomy impacts (updated Dec 2025)
• Spaceflight Now: Starlink launch coverage (Dec 2025)

Published in Ursa Cortex: The Ursa Majors Group Blog