Tag Archives: Donald Kessler

Keeping Track of Satellites

The topic of satellite broadband has been heating up lately. Elon Musk’s StarLink now has over 540 broadband satellites in the sky and is talking about starting a few beta tests of the technology with customers. OneWeb went into bankruptcy but it being bought out by a team consisting of the British government and Bharti Airtel, the largest cellular company in India. Jeff Bezos has continued to move forward with Project Kuiper and the FCC recently gave the nod for the company to move ahead.

These companies have grandiose plans to launch large numbers of satellites. Starlink’s first constellation will have over 4,000 satellites – and the FCC has given approval for up to 12,000 satellites. Elon Musk says the company might eventually grow to over 30,000 satellites. Project Kuiper told the FCC they have plans for over 3.300 satellites. The original OneWeb plan called for over 1,200 satellites. Telesat has announced a goal of launching over 500 satellites. A big unknown is Samsung, which announced a plan a year ago to launch over 4,600 satellites. Even if all of these companies don’t fully meet their goals, there are going to be a lot of satellites in the sky over the next decade.

To put these huge numbers into perspective, consider the number of satellites ever shot into space. The United Nations Office for Outer Space Affairs (NOOSA) has been tracking space launches for decades. They reported at the end of 2019 that there have been 8,378 objects put into space since the first Sputnik in 1957. As of the beginning of 2019, there were 4,987 satellites still in orbit, although only 1,957 were still operational.

There is a lot of concern in the scientific community about satellite collisions and space junk. Low earth satellites travel at a speed of about 17,500 miles per hour to maintain orbit. Satellites that collide at that speed create many new pieces of space junk, also traveling at high speed. NASA estimates there are currently over 128 million pieces of orbiting debris smaller than 1 square centimeter, 900,000 objects between 1 and 10 square centimeters, and 22,000 pieces of debris larger than 4 inches.

NASA scientist Donald Kessler described the dangers of space debris in 1978 in what’s now described as the Kessler syndrome. Every space collision creates more debris and eventually there could be a cloud of circling debris that will make it nearly impossible to maintain satellites in space. While scientists think that such a cloud is almost inevitable, some worry that a major collision between two large satellites, or malicious destruction by a bad actor government could accelerate the process and could quickly knock out all of the satellites in a given orbit.

There has only been one known satellite collision when a dead Russian satellite collided with an Iridium communications satellite over a decade ago. That satellite kicked off hundreds of pieces of large debris. There have been numerous near misses, including with the manned Space Station. There was another near-miss in January between the defunct Poppy VII-B military satellite from the 1960s and a retired IRAS satellite that was used for infrared astronomy in the 1980s. It was recently reported that Russia launched a new satellite that passed through one of StarLink’s newly launched swarms.

The key avoiding collisions is to use smart software to track trajectories of satellites and provide ample time for the satellite owners to make corrections to the orbital path to avoid a collision. Historically, that tracking role has been done by the US military – but the Pentagon has made it clear that it is not willing to continue in this role. No software is going to help avoid collisions between dead satellites like the close-call in January. However, all newer satellites should be maneuverable to help avoid collisions as long as sufficient notice is provided.

A few years ago, the White House issued a directive that would give the tracking responsibility to the Commerce Department under a new Office of Space Commerce. However, some in Congress think the proper agency to track satellites is the Federal Aviation Agency which already tracks anything in the sky at lower levels. Somebody in government needs to take on this role soon, because the Pentagon warns that its technology is obsolete, having been in place for thirty years.

The need for tracking is vital. Congress needs to decide soon how this is to be done and provide the funding to implement a new tracking system. It would be ironic if the world solves the rural broadband problem using low orbit satellites, only to see those satellites disappear in a cloud of debris. If the debris cloud is allowed to form it could take centuries for it to dissipate.

The Busy Skies

I was looking over the stated goals of the broadband satellite companies and was struck by the sheer numbers of satellites that are being planned. The table further down in the blog shows plans for nearly 15,000 new satellites.

To put this into perspective, consider the number of satellites ever shot into space. The United Nations Office for Outer Space Affairs (NOOSA) has been tracking space launches for decades. They report that there have been 8,378 objects put into space since the first Sputnik in 1957. As of the beginning of 2019, there were still 4,987 satellites still in orbit, although only 1,957 were still operational.

There was an average of 131 satellites launched per year between 1964 and 2012. Since 2012 we’ve seen 1,731 new satellites, with 2017 (453) and 2018 (382) seeing the most satellites put into space.

The logistics for getting this many new satellites into space is daunting. We’ve already seen OneWeb fall behind schedule. In addition to these satellites, there will continue to be numerous satellites launched for other purposes. I note that a few hundred of these are already in orbit. In the following table, “Current” means satellites that are planned for the next 3-4 years.

Current Future Total
SkyLink 4,425 7,528 11,953
OneWeb 650 1,260 1,910
Telesat 117 512 629
Samsung 4,600 4,600
Kuiper 3,326 3,326
Boeing 147 147
Kepler 140 140
LeoSat 78 30 108
Iridium Next 66 66
SES 03B 27 27
Facebook 1 1
 Total 5,192 9,300 14,492

While space is a big place, there are some interesting challenges from having this many new objects in orbit. One of the biggest concerns is space debris. Low earth satellites travel at a speed of about 17,500 miles per hour to maintain orbit. When satellites collide at that speed, they create a large number of new pieces of space junk, also traveling at high speed. NASA estimates there are currently over 128 million pieces of orbiting debris smaller than 1 square centimeter and 900,000 objects between 1 and 10 square centimeters.

NASA scientist Donald Kessler described the dangers of space debris in 1978 in what’s now described as the Kessler syndrome. Every space collision creates more debris and eventually there will be a cloud of circling debris that will make it nearly impossible to maintain satellites in space. While scientists think that such a cloud is almost inevitable, some worry that a major collision between two large satellites, or malicious destruction by a bad actor government could accelerate the process and could quickly knock out all of the satellites in a given orbit. It would be ironic if the world solves the rural broadband problem using satellites, only to see those satellites disappear a cloud of debris.

Having so many satellites in orbit also concerns another group of scientists. The International Dark Sky Association has been fighting against light pollution that makes it hard to use earth-based telescopes. The group now also warns that a large number of new satellites will forever change our night sky. From any given spot on the Earth, the human eye can see roughly 1,300 visible stars. These satellites are all visible and once launched, mankind will never again see the natural sky that doesn’t contains numerous satellites at any given moment.

Satellite broadband is an exciting idea. The concept of bringing good broadband to remote people, to ships, and to airplanes is enticing. For example, the company Kepler listed above is today connecting to monitors for scientific purposes in places like lips of volcanos and on ocean buoys and is helping us to better understand our world. However, in launching huge numbers of satellites for broadband we’re possibly polluting space in a way that could make it unusable for future generations.