Thus, the ability  of  being  functional  through time,  known  as functionability, is  an  essential  property of functionability processes. From functionability point of view, at any instant of time functionability process can be in one of the following two states [4]:

Positive Functionability State, PFS, which is the state of being functional

Negative Functionability State, NFS, which is the state of not being functional

The motion of the functionability process through functionability states is governed by the occurrence of functionability events, which are classified as:

Positive Functionability Events, PFE, which cause the transition from NFS to PFS

Negative Functionability Events, NFE, which cause the transition from PFS to NFS

Examples of MIRCE Functionability Actions in Orbital Debris Environment:

- January 24, 1978. Cosmos (Kosmos) 954 uncontrolled reentry.

Cosmos 954 was a Soviet nuclear-powered Radar Ocean Reconnaissance Satellite (RORSAT) that launched from the Baikonur cosmodrome on September 18, 1977. Only 4 months later on January 24, 1978, Cosmos 954 crashed into Canada’s Northwest Territories, scattering large amounts of radioactive material across 124,000 km2, from Great Slave Lake into northern Saskatchewan and Alberta. To produce the energy necessary for this type of operation, the RORSATs used a nuclear power source. Before the fuel is spent in a RORSAT, its operators send the satellite into a higher “graveyard” orbit between 800 km and 1,000 km. Unfortunately, Cosmos 954’s propulsion system failed for reasons unknown, causing it to reenter Earth’s atmosphere before it could be sent to the graveyard orbit.

MIRCE Science mechanism of negative functionability event: Unknown [Built-in design error, Imposition of external overstress mechanisms or Irreversible changes in the condition of components with time]

- 1992 and 1993. Meteor storm impact on the Hubble Space Telescope, delay in the launch of space shuttle mission STS-51 and Olympus telecommunication satellite.

In 1992, the possibility of a storm from the well-known Perseid meteor shower became a sudden and real possibility with the surprise discovery of the Perseid parent comet, 109P/Swift-Tuttle, as it passed through the inner solar system. The prospect of a substantial storm the following year led to the reorientation of the Hubble Space Telescope near the time of the predicted storm peak and to a delay in the launch of space shuttle mission STS-51. The 1993 shower resulted in a strong surge in meteor numbers but fell short of a storm. The Olympus spacecraft was a European Space Agency (ESA) experimental communications satellite that experienced multiple anomalies on August 11, 1993, near the peak of the Perseid meteor shower that year. Olympus lost Earth-pointing attitude and began spinning out of control after having been in orbit for 5 years.

MIRCE Science mechanism of negative functionability event: Imposition of external overstress mechanisms

- January 11, 2007. China conducted a direct-ascent anti-satellite (ASAT) missile test.

On January 11, 2007, China conducted a direct-ascent anti-satellite (ASAT) missile test with its FENGYUN 1C polar-orbiting weather satellite as the target. The destruction of the satellite created more than 3,000 tractable objects and an estimated 150,000 debris particles larger than 1 cm, making it the largest debris-generating event in the history of man-made orbital debris, increasing the known existing orbital debris population in 2007 by more than 15 percent. For comparison, the previous largest orbital debris-generating event, the explosion of a U.S. Pegasus rocket body in 1996, created 713 tractable pieces of debris. On June 22, 2007, NASA was forced to maneuver its Terra satellite to avoid debris from China’s ASAT test.

MIRCE Science mechanism of negative functionability event: Imposition of external overstress mechanisms

- February 21, 2007. United States successfully destroyed its National Reconnaissance Office operated USA-193 satellite.

On February 21, 2007, the United States successfully destroyed its National Reconnaissance Office operated USA-193 satellite, because it posed a serious threat to Earth. The purpose of this missile intercept was to break up the spacecraft and, more specifically, its thick metal fuel tank, which was nearly three-quarters full of toxic hydrazine propellant used for maneuvering the satellite while in orbit. Because USA-193 failed shortly after reaching orbit, its fuel would never be depleted through normal operational use. The Department of Defense and NASA had run tests that determined that the hydrazine tank would survive atmospheric entry intact and thus pose a risk of casualties from dispersal of the deadly hydrazine fuel. Unlike the Chinese FENGYUN 1C satellite remnants, debris from USA-193 reentered Earth’s atmosphere within 4 months of the satellite’s destruction.

MIRCE Science mechanism of negative functionability event: Imposition of external overstress mechanisms

- February 10, 2009. On-Orbit Collision of Iridium 33 and Cosmos 2251.

The destruction of Iridium 33 was confirmed when the U.S. Space Surveillance Network (SSN) detected debris clouds in the orbits of both Iridium 33 and Cosmos 2251, marking the first payload-to-payload collision in the history of spaceflight. The collision of Iridium 33 and Cosmos 2251 added an additional 2,181 tractable pieces of debris to the approximately 19,000 objects larger than 10 cm already in orbit in 2009. Prior to the Iridium–Cosmos collision, Iridium had never made an on-orbit maneuver with one of its satellites in response to a close approach prediction. Between February 2009 and February 2011, Iridium made 41 collision mitigation maneuvers based on 46 close approach warnings, however, all of these actions were integrated into normal constellation maintenance actions and so had little impact on Iridium operations.

MIRCE Science mechanism of negative functionability event: Imposition of external overstress mechanisms

- August 23, 2016. Sentinel-1A space debris collision.

The Sentinel-1A solar panel was hit by a small piece of space debris or micrometeoroid on August 23, 2016. at 17:07 UTC. A sudden small power reduction was observed in a solar array of Sentinel-1A, orbiting at 700 km altitude, at 17:07 GMT on 23 August. Slight changes in the orientation and the orbit of the satellite were also measured at the same time. The size of the affected area was about 40cm in diameter caused by a particle just a few mm in diameter. The drop in power was about 280 W or 5% of the total available occurred.

MIRCE Science mechanism of negative functionability event: Imposition of external overstress mechanisms

- December 23, 2021. Sentinel-1B anomaly.

This major Sentinel-1B anomaly occurred on December 23, 2021. The first effect was a failure of the SAR instrument to respond to the main avionics 1553 data bus, which had some impacts on other sub-systems including some thermal and propulsion subsystems elements. One mode was highlighted, and is related to a potential leakage of a ceramic capacitor which is part of the main and redundant regulators of the 28V power regulated bus. This capacitor had to be replaced as a result of a non-compliance detected during the manufacturing and testing phase. For the repair, the capacitor was soldered using a process that may have damaged the component although it was fulfilling product assurance requirements applicable at the time it was applied. This repair process is no longer authorized following revision of applicable ECSS standard in 2017. This process was also used on the Sentinel-1A C-SAR Antenna Power Supply unit (CAPS), but not on the Sentinel-1C and Sentinel-1D CAPS units. The soldering process used on this capacitor is considered the most probable root cause for the failure of the main regulator and a possible root cause for the failure of the redundant regulator. Additional failure modes and other CAPS root causes such as double failure due to independent causes cannot, however, be excluded. The consequence of this event was the end of mission of the Copernicus Sentinel-1B satellite on August 3, 2022.

MIRCE Science mechanism of negative functionability event: Built-in design error

- February 8, 2022. SpaceX geomagnetic storm force 40 Starlink internet satellites to reenter.

A SpaceX Falcon 9 rocket launched 49 Starlink satellites on Thursday (Feb. 3) from NASA's historic Pad 39A at the Kennedy Space Center in Florida. A day later, a geomagnetic storm above Earth increased the density of the atmosphere slightly, increasing drag on the satellites and dooming most of them. Preliminary analysis show the increased drag at the low altitudes prevented the satellites from leaving safe-mode to begin orbit raising maneuvers, and up to 40 of the satellites will reenter or already have reentered the Earth’s atmosphere. 

MIRCE Science mechanism of negative functionability event: Imposition of external overstress mechanisms

- August 29, 2023. Old Soviet satellite breaks apart in orbit after space debris collision.

The disintegration of the satellite, either the Kosmos-2143 or Kosmos-2145 spacecraft, was reported by astrophysicist and space debris expert Jonathan McDowell. 7 debris objects cataloged from a defunct Soviet communications satellite launched in 1991. Debris appears to be from either Kosmos-2143 or Kosmos-2145, two of 8 Strela-1M satellites launched on the same rocket.

MIRCE Science mechanism of negative functionability event: Imposition of external overstress mechanisms

- September 13, 2023. Derelict Soviet-era payload had a conjunction with a Chinese rocket body.

On Sept 13, a derelict Soviet-era payload had a conjunction with a Chinese rocket body. The miss distance was 36 m (± 13 m) and the probability of collision was 1E-3 (i.e., 0.1% or 1/1,000). If these two objects had collided, the number of resulting cataloged fragments would have likely been ~3,000. To put that into perspective, the 2021 Russian ASAT test resulted in ~1,800 total cataloged fragments over time. 

MIRCE Science mechanism of negative functionability event: Imposition of external overstress mechanisms

- November 2, 2023. Astronaut lost tool bag during spacewalk.

A tool bag that gave astronauts the slip during a spacewalk at the International Space Station is surprisingly bright and can be seen with binoculars. The bag of tools gave NASA astronauts Jasmin Moghbeli and Loral O'Hara the slip on Nov. 2, 2023, as they were conducting a spacewalk outside of the International Space Station (ISS). The tool bag is now orbiting our planet just ahead of the ISS.

MIRCE Science mechanism of negative functionability event: Human error in execution of maintenance tasks

- February 26, 2024. Cruise ship navigates through space debris warning zone.

Island Princess cruise passengers receive captain’s warning of potential space debris fallout in the Indian Ocean during world cruise. This warning is regarding space debris that will be falling into the ocean, an area that Island Princess will be crossing on the way to Port Louis, Mauritius,” wrote Captain Cataldi. “We estimate that we will be at the boundary of the navigational warning on the 26th of February at 21:15. We will exit the area on the 27th of February at 9:30.”

MIRCE Science mechanism of negative functionability event: Imposition of external overstress mechanisms

- February 28, 2024. Close conjunction at 608 km between two non-maneuverable spacecraft.

At approximately 06:30 UTC (Wed, 28 February) LeoLabs observed a close conjunction at 608 km between two non-maneuverable spacecraft: a derelict Russian Cosmos 2221 satellite and an operational NASA’s Thermosphere Ionosphere Mesosphere Energetics and Dynamics Mission (TIMED) spacecraft. The miss distance was less than 20 meters with a probability of collision (PC) of 3 – 8% at the time of closest approach (TCA). 

MIRCE Science mechanism of negative functionability event: Imposition of external overstress mechanisms