May 21, 2021

The Art & Science of Minimizing Orbital Debris

By Charles Miller

The world is entering an inflection point. We can’t see it. And most of us don’t even know that this critical juncture exists. We are opening the space frontier, and many thousands of satellites will soon be launched into orbit to connect the world, which will change the lives of every man, woman and child on Earth.

However, there is a downside. We could ruin the environment of space for every man, woman and child.  We are all at risk from bad actors — actors who refuse to take responsible and appropriate steps to understand and mitigate the risks of their actions in space, such as from orbital debris.

Orbital debris is space junk that is still in Earth orbit.  Dead satellites, left-over rocket stages, and pieces from satellites that have crashed or exploded. The US Space Force is currently tracking about 25,000 of these objects that are 10 cm or larger, and it is estimated that nearly a million pieces are 1 cm or larger. The debris is moving at about 7 kilometers per second, about 20 times faster than a bullet, so colliding with even the smallest piece of debris can be catastrophic.

Lynk is on the record with recommendations to the U.S. Government advocating for smart action to minimize the risks of orbital debris. 

But actions speak louder than words.

Lynk has intentionally designed our system to minimize the risk of orbital debris. 

Here is how …

1) Small spacecraft are low-risk spacecraft

Small spacecraft have much lower collision risk.  It turns out that the risk from a collision is a function of size … squared.

There are two factors which compound. Small satellites have a smaller “probability” of collision. Small satellites also have lower mass, and therefore have a smaller “consequence” of collision.  

Risk is equal to “Probability” times the “Consequence”.

Small is good.

2) A low-risk plan for high reliability

Not all satellite manufacturers are equal. While America encourages risk-taking, we also use common sense. A new company can design a new large airplane, but we would never allow them to fly their new airplane over heavily populated areas before it was proven safe.  Instead, they would be required to fly the airplane in a remote area where nobody lives, and prove it is reliable first.  

Somebody who has never built a high-risk large satellite before should not be allowed to fly the satellite in heavily populated orbits. It is just common sense.

There is a rational way for companies to develop reliable satellite technology. No faith-based “trust us” system engineering is required. 

Lynk will prove reliability by flight demonstration … step by step. Lynk’s process is to design, test, launch, learn … and repeat … to increase reliability.

We have already launched 4 small satellites to space, 3 of which are de-orbited. Later this year we will launch three more.

Lynk will launch and test more than 100 spacecraft, in small batches spread over years, before we launch the thousands of satellites needed for a full constellation. Lynk will use this iterative design process to increase reliability (and lower risk of on-orbit failure) generation by generation.

3) We will operate in a “self-cleaning orbit”

Sometimes satellites die in their operational orbit. A dead satellite that stays in orbit for a long period has a much greater chance of a collision. A dead satellite in an orbit above 700 km will stay in orbit for decades.

In lower orbits satellites naturally run into more of the diffuse upper atmosphere. This diffuse atmosphere slows the satellite down, and significantly lowers the orbital lifetime of the satellite (unless you reboost it.)

Below 550 km, where Lynk intends to go, a dead satellite will de-orbit much faster … in a couple years. Space junk – dead satellites – is naturally removed and burns up in the atmosphere. This significantly reduces the risk.

4) On-orbit check-out in a super safe orbit.

Satellites are more likely to die at the beginning of life, which is called “infant mortality” in the industry. For this reason, Lynk plans to conduct initial on-orbit checkout of our large constellations in very low LEO, below 375 km. If a satellite dies because of a manufacturing flaw, it will de-orbit in a few months.

5) Controlled and safe de-orbit of satellites at end-of-life.

We will intentionally de-orbit satellites near the end of life using on-board satellite propulsion. The satellites will be designed to completely burn up in the atmosphere. There will be no chance of damage on the ground.

6) Agreeing to be regulated by the FCC

Lynk is intentionally applying for our operator’s license from the FCC, the world’s premier spectrum regulator. Why is this a big deal?

Some companies intentionally engage in forum shopping … purposely applying for a license from a country that doesn’t apply the same technical and regulatory standards. This is a bad deal for the entire world when a company’s technology is unproven, and their proposed system creates a major risk of orbital debris.  We are all hurt by this kind of forum shopping. It should be prohibited.

Conclusion

Lynk supports the focus by the US Government, and by leading nations of the world, on addressing the problem of orbital debris. We are at a tipping point to a very dangerous situation in space. In the next decade, we expect to see orders of magnitude more satellites operating in orbit.  

Action is needed now. The US Congress should authorize the Department of Commerce to act, and our international partners in space should implement those same high standards.