Buzz
There are currently at least 500,000 objects in orbit around Earth, with some estimates reaching nearly 700,000. Over 21,000 of these objects exceed 10 centimeters in size, posing a risk to both space travel and life on Earth. Many of these are debris from destroyed artificial satellites that collided with other satellites.
As of today, there are more than 1,700 active artificial satellites, along with about 2,600 non-functioning ones. The majority of these satellites have either completed their missions or have failed. Of these, at least 30 once operated on nuclear power, and some still leak nuclear waste to this day.
The following list outlines 10 concerning objects orbiting Earth, each with unique risks.
10. Tiangong-1
Launched by the Chinese government in 2011, Tiangong-1 was a prototype space station. Its initial two-year mission aimed to explore the effects of space travel on astronauts and assess the docking capabilities of other spacecraft. However, the mission was extended beyond the initial plan, only to be abandoned after the Chinese operators admitted losing control of the station.
Weighing approximately 8,500 kilograms (19,000 lbs), Tiangong-1 was a sizable station designed to accommodate two astronauts at a time.
While most of Tiangong-1 disintegrated upon reentry into Earth's atmosphere over the Pacific Ocean in April 2018, it was believed that the rocket engines were made of materials that would withstand burning up. Despite early concerns about potential damage to structures, animals, and humans from any remaining intact parts, no major incidents were reported.
9. SNAP 10-A
In 1965, the United States launched SNAP 10-A into space from Vandenberg Air Force Base. This satellite remains the only nuclear fission spacecraft the U.S. has ever sent into orbit. It was designed as an experimental vehicle to generate 500 watts of electrical power and study the behavior of nuclear reactors in space.
Regrettably, the reactor only operated for 43 days before a failure in the voltage regulator disrupted the power supply. By the late 1970s, the satellite began to break apart, creating about 50 pieces of debris.
During the disintegration, it is highly probable that some radioactive material was released into space. The reactor still orbits Earth at a distance of 700 nautical miles and is projected to remain in orbit for the next 4,000 years unless further shedding occurs or a collision with another object shortens its life.
8. Kosmos 1818
In 1987, the Soviet Union launched Kosmos 1818, a satellite powered by the TOPAZ 1 thermionic nuclear reactor. Its primary mission was as a Radar Ocean Reconnaissance Satellite (RORSAT) for naval surveillance. Unfortunately, the reactor stopped functioning after just five months.
In 1978, a similar satellite reentered Earth's atmosphere and crashed in Canada, dispersing radioactive material. To prevent a similar catastrophe, Kosmos 1818 was placed in a high orbit. However, this also increased its potential for collision.
Any potential collision could accelerate the descent of radioactive materials to Earth. Some of the debris and liquids released from the spacecraft are believed to still be radioactive and remain in orbit.
7. Kosmos 1867
Kosmos 1867, launched by the Soviet Union in 1987, shared its mission with its twin, Kosmos 1818. However, Kosmos 1867 remained operational for 11 months before its systems shut down.
Like its twin, Kosmos 1867 is in a high orbit and has experienced the stresses of repeated solar heating. This has caused the coolant tubes of its nuclear reactor to crack, leading to the release of liquid metal into space.
6. Kosmos 1900
Kosmos 1900 is a US-A or Controlled Active Satellite designed for RORSAT missions. Launched by the Soviet Union in 1987, the satellite faced significant problems from the start and never achieved the intended cruising orbit.
Despite several attempts with rocket boosts to adjust its orbit, the satellite continued to lose altitude. Additionally, the nuclear reactor failed to reach its designated storage orbit. By 1995, NASA confirmed the presence of a cloud of liquid radioactive material originating from Kosmos 1900. It was believed the leak resulted from a collision with another satellite.
5. Satellite Debris
With the growing number of satellite collisions, Earth now has a vast debris field orbiting it. This debris is possibly more hazardous than any single intact object, as it increases the likelihood of further collisions between multiple debris pieces. Several significant satellite collisions have been recorded, worsening the issue of space junk.
In 2009, the Iridium 33 satellite collided with Kosmos 2251 at a speed of 42,000 kilometers per hour (26,000 mph) while both were in low Earth orbit, approximately 800 kilometers (500 miles) above the surface. The collision resulted in the complete destruction of both satellites.
Instead of two large objects in orbit, there are now around 1,000 pieces larger than 10 centimeters (4 inches) threatening other satellites. In addition, many smaller fragments also pose risks.
Although half of the debris from the 2009 crash has burned up in the atmosphere, other collisions have since occurred. Experts believe that the Iridium-Kosmos accident, coupled with China's deliberate destruction of a satellite using a long-range missile in 2007, has doubled the number of objects that could potentially collide in space.
4. Black Knight
The potential danger of the Black Knight depends on who you ask. While conspiracy theorists suggest it is a 13,000-year-old extraterrestrial satellite from the star system Epsilon Bootis, allegedly discovered by Nikola Tesla in 1899, NASA insists it's merely a thermal blanket that got detached during a spacewalk.
The real danger posed by this object comes from the time conspiracy theorists waste on it. In fact, more time has been spent speculating about Black Knight than the amount of time lost by those who died as a result of falling space debris.
3. Envisat
Launched in 2002, Envisat is a large satellite designed to monitor Earth's environment and geography. Although it operated five years beyond its original mission, the European Space Agency (ESA) lost contact with it in 2012. Today, Envisat represents the largest threat contributing to the Kessler syndrome in Earth's orbit.
Two objects are currently on a collision course with Envisat, which could have catastrophic consequences. Given Envisat’s mass of around 8,200 kilograms (18,000 lbs), a crash with other satellites or space debris would result in a massive debris field, nearly impossible to clean up.
The destruction of Envisat would generate a tremendous amount of debris, and the ensuing chain reaction of collisions described by the Kessler syndrome is the primary risk, with Envisat being the greatest contributor to this potential hazard.
At present, Envisat is expected to remain in orbit for around 150 years before eventually falling to Earth, increasing the likelihood of a collision. For this reason, efforts are underway to design a spacecraft capable of removing Envisat from orbit.
Envisat embodies a great irony in our space exploration efforts: a satellite once hailed for advancing our understanding of Earth's environmental health now poses one of the biggest threats to the very space environment it once helped to study.
2. Hubble Space Telescope
Although the Hubble Space Telescope is smaller than the ISS, it is still one of the most massive objects in orbit and represents a significant risk mainly because of its potential for collisions. A collision with another satellite or debris would generate considerable additional wreckage, worsening the existing space debris problem.
Hubble was originally launched aboard the Discovery space shuttle in 1990, following a delay caused by the Challenger disaster. At present, Hubble is on an uncontrolled orbit and is gradually descending toward Earth.
Due to the durability and density of Hubble's materials, the telescope is unlikely to burn up during its re-entry into Earth's atmosphere. Instead, it will likely fall uncontrollably to the Earth's surface, a process expected to occur sometime before 2040.
1. ISS
The International Space Station (ISS) doesn't pose a nuclear or collision risk that we know of, but its enormous size makes it one of the most hazardous objects in orbit. A collision with any other space object could set off a catastrophic series of events, potentially leading to a doomsday scenario caused by space debris, as theorized by the Kessler syndrome.
In simple terms, this means that if an object were to strike the ISS, it could trigger a chain reaction of similar incidents, leading to the creation of even more debris. Eventually, the debris could become so widespread that space activities may be halted for generations. As recently as 2017, objects have separated from the station, creating a risk of collision with the ISS.
The ISS also poses a risk to its crew members. Numerous issues have arisen, including problems with the oxygen generators, carbon dioxide removal systems, environmental controls, central computer, electrical and power systems, damaged solar panels, and ammonia leaks. Should any of these issues escalate into a disaster, the ISS could quickly become a serious hazard, falling to Earth and colliding with other satellites and debris on its way down.
