Advances in rocket and space exploration technology are pushing Earth's boundaries like never before. But while these advancements are allowing humanity to look beyond, they also come with significant risks, namely uncontrolled rocket debris falling from the sky without warning.

Fortunately, new technological advancements are aiding scientists and engineers in controlling this descent to protect public safety and security on Earth's surface.

What goes up...

The problem of rocket debris has been a major concern in recent years, as the number of launches into space has rapidly increased. Rocket stages that are left in orbit can make an uncontrolled re-entry into Earth's atmosphere once they begin to experience atmospheric drag. Satellites and other bodies orbiting around Earth in the exosphere generally do not experience a high amount of drag. However, objects in orbit anywhere below the exobase - the boundary layer between the thermosphere and exosphere - need to boost their orbit up four times per year, according to NOAA, to stay stable in their orbit.

Many of these objects that undergo an uncontrolled re-entry will burn up by the extreme temperatures created by the fluid drag as the object descends and reaches more dense atmospheric layers. However, many small parts, and sometimes enclosures, nacelles and fuselages, will fall to the ground at extremely high speed. According to NASA, on average, one catalogued item uncontrollably re-enters Earth's atmosphere each day, about up to 90% of the item is burned up on re-entry.

These remnants can be extremely dangerous. What's more, even surviving fragments pose a physical threat; for instance, chunks of metal could cause severe damage upon impact. In fact, according to research from the University of British Columbia, there is a 6-10% chance that re-entering rocket stages could seriously hurt or kill someone within the next 10 years. However, the chances of a specific individual being killed by orbital debris is one in one trillion.

Besides the obvious impact danger, some contain hazardous materials, such as toxic propellants or fuel, which can threaten human health and safety. Also, as more rockets go up, and more debris remains in orbit, it increases the likelihood of a catastrophic incident between "space trash" and space craft.

Due to the potential dangers posed by these objects, however seemingly minimal, it is important for space agencies and other organizations to work together to mitigate this risk.

Must come down - safely

Whenever possible, orbital items, like space stations and satellites, are brought back to Earth with a controlled re-entry. Space agencies will ensure debris and other bodies crash into oceans or poles - locations with less risk of a human impact. Yet not all orbital objects are equipped with re-entry technologies. Or the re-entry avionics may fail. As a result, several technologies have emerged to resolve this.

ARDV illustration. Source: NASAActive Debris Removal Vehicle (ADRV)

In 2022, NASA announced they were looking for commercial partners to help them bring the ADRV patent to life. This is a dedicated low Earth orbit vehicle that will capture stray space debris and return it in a controlled descent.

NASA developed several unique technologies to support the ADRV program, including a debris tracking and identification system; a spaceflight system to alter the ADRV's trajectory to intercept the object; and a capture and storage system, to contain the debris until it returns to Earth.

ELSA-d and Astroscale

Since March 2021, a unique "space sustainability" effort has been conducted by the Japanese space organizaton Astroscale. The ELSA-d mission is a proof of concept that their two-satellite system can safely deorbit many types of orbital debris.

CALT parafoil

A new parachute system developed by the China Academy of Launch Vehicle Technology (CALT) aims to enhance the safety of Chinese satellite launches from inland spaceports. The system deploys a parafoil at a predetermined altitude during descent, guiding the spent rocket booster to a specific landing area. This innovation reduces the landing zone size by 80%, minimizing evacuation needs and decreasing potential damage to property and harm to individuals.

China's increasing launch activities have heightened concerns about spent boosters falling in populated areas. China's expanding space endeavors include a coastal spaceport, Wenchang, and plans for a commercial spaceport. Additionally, efforts toward reusable rockets aim to mitigate space debris threats.

Why aren't controlled entry technologies standard?

Part of this can be attributed to the lack of global cooperation on a comprehensive approach to tackling space debris. Without universal regulations or standards, individual countries' efforts have been fragmented at best, largely driven by commercial interests rather than environmental and human protection. A push toward more effective international collaboration is needed to make significant progress in dealing with the orbital waste problem.

A further hurdle is the cost of innovation and implementation when it comes to debris control measures. Parachute-controlled deorbiting, for example, is undoubtedly one of the most effective and promising solutions to tackle orbital debris. However, in order for this method to become widespread and commonplace among space-faring nations, substantial development and testing must be conducted first, and that costs money. Furthermore, there are currently no multilateral agreements mandating that companies make these changes; rather than being incentivized through financial or regulatory means, firms tend to be hesitant or unwilling to bear the cost themselves.

Mandates have proven to be effective in the past, as evidenced by the success of measures taken to phase out chlorofluorocarbons and transition oil tankers from single to double hulls. There needs to be a similar push for a global standard when it comes to controlling space debris and an opportunity for companies to benefit financially too. Only then can real progress be made in reducing the ever-growing orbital waste problem.

The future of orbit debris control

This almost certainly seems like an opportunity for international standardization. Although no space technology standards body has been identified yet, there are national-level efforts and other associations working on this.

Until then, it is unlikely to be major concern until the worst occurs - either major damage or injuries due to unchecked space debris.