by There is an interesting residual fall from the European Remote Sensing satellite, or ERS-2, recently on Earth.
After its launch in April 1995, ERS-2 studied our planet for almost 16 years. Then, in 2011, the European Space Agency (ESA) decided to end the mission of the radar-toting spacecraft. The agency ordered a series of deorbit maneuvers, which lowered the average altitude of the satellite and mitigated the risk of collision with other satellites or space debris.
The spacecraft was also “passivated” to reduce the risk of fragmentation. Passivation involves getting rid of internally stored energy, such as venting an unused drive and discharging batteries (which can cause an explosion if left charged).
“There’s no intervention from the ground, so ERS-2 will come back completely naturally – which is now common with the average return to one spacecraft. The Earth’s Atmosphere per month,” explained ESA’s pre-collapse statement. It could be argued, however, that the term “completely natural return,” is an easy-to-use substitute for “uncontrolled.”
Related: The largest spacecraft to fall uncontrolled from space
After the fall
ESA’s Space Debris Office predicted that ERS-2’s re-entry would occur on February 21 at 10:41 am EST (1541 GMT). In reality, the craft disintegrated two hours later, re-entering the atmosphere over the North Pacific.
The European Space Operations Center (ESOC), home to engineering teams that control spacecraft in orbit, noted that the earlier prediction came within a value of plus or minus 1.44 hours.
Still, in the uncontrolled space debris business, minutes – indeed, even seconds – count. They can mean the difference between a space dune falling into remote ocean waters or crashing within a populated area.
Indeed, parts of the 2.5-tonne ERS-2 likely survived the fiery re-entry. On average, between 10% and 20% of the mass of larger objects pass through the atmosphere and hit the ground or water, said Simona-Elena Nichiteanu, ESOC’s media relations officer.
Before the crash of ERS-2, Nichiteanu told Space.com that the largest and heaviest fragments that could reasonably survive were four spacecraft tanks, a trio of internal panels that support spacecraft instruments and the antenna structure for an antenna The satellite’s Synthetic Aperture Radar, could be there. the biggest piece, assuming it didn’t break apart.
But it is unlikely that we will know how many of the ERS-2 bus attempts survived, because of the locale reentry.
“No property damage was reported,” explained the ESA statement after the ERS-2 crash.
Related: Large doomed satellite seen from space as it falls towards fiery re-entry on February 21 (photos)
Satellite falls willy-nilly
But the willy-nilly nature of falling out of control satellite yes reason for the wills.
That’s the view of Ewan Wright, Ph.D. candidate at the University of British Columbia and a junior fellow of the Outer Space Institute. It is actively focused on the sustainability of the outer space environment.
In the future, Wright told Space.com, all large satellites should perform controlled re-entries.
“Operators should control them to re-enter over the oceans, away from people, aircraft and ships,” Wright said. “ERS-2 re-entered the North Pacific. If it had re-entered half an hour earlier, it could have hit Europe or Africa,” he said.
And the North Pacific sees air traffic traveling between Asia and North America, and to Hawaii, Wright said.
“Fortunately, aircraft were not affected this time,” he said. “Even if aircraft are not hit by space debris, the uncertainty can cause airspace closures and route diversions, costing airlines and passengers money.”
Ship traffic is also a concern — and not just in the final re-entry zone, because of how fast orbital objects move. Pieces of broken satellites may come down over a wide stretch of the object’s re-entry trajectory.
In fact, an ERS-2 debris warning was reported for the Princess Cruises ship carrying 2,200 passengers, according to cruiseradio.net. The ship, Island Princess, was informed by a coordinated message from ESA and the National Hydrographic Office that the odds and ends of ERS-2 might fall into the area where the pleasure boat was to pass, en route to Port Luis, Mauritius . The Island princess was steered out of the area, taking another course.
For Wright, the bottom line is this: “We should not rely on luck to mitigate casualty risks. Instead of rolling the dice, operators should use controlled reentries, asking satellites re-entry from people and aircraft.”
Global standard
Darren McKnight is a senior technical fellow for LeoLabs, a commercial provider of space domain awareness services and low earth orbit mapping based in Menlo Park, California.
McKnight said the likelihood of ground casualties from a single re-entry is low. However, the aggregate risk increases over time.
“It’s not a question of ‘if’ but ‘when’ an abandoned object will survive to Earth’s surface and result in significant damage, death or injury,” McKnight told Space.com.
And when that fateful day comes, there will be a shutter for uncontrolled satellite re-entries, McKnight said. The “world standard” is the 25-year rule – that is, removing all satellites from orbit within 25 years of the end of their mission, he said.
“But the United States is the only one that requires operators to minimize the risk of injury to people on the ground from reentry,” McKnight said. “This will be happening just as the 25-year rule is changing to a five-year rule, one that is only required by the Federal Communications Commission at this point.”
Old rules
On the other hand, we will have decades of conversions based on the old rules, McKnight said. Besides, most of the derelict mass currently in orbit, he said, is stuff that was launched in the 1980s and 1990s, when there were no mitigation rules at all.
The longer regulations emerge, the more complicated it will be to determine their merits, since there is a mix of hardware in orbit, McKnight said.
“I also think it’s interesting that since regulation is pushing operators to design the spacecraft to decompress and make sure they disintegrate on reentry, some people are now concerned about atmospheric contamination. from space launch effluent and disintegrating re-entry spacecraft,” McKnight noted.
That situation is getting more complicated as the amount of content grows and increases, according to McKnight. “No one is going to be happy!” he said.
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Dead-satellite collapses like ERS-2 happen regularly, said Leonard Schulz, a researcher at Germany’s Institute of Geophysics and Extraterrestrial Physics at Technische Universität Braunschweig.
Such re-entries will only increase in the future, Schulz told Space.com, due to the increasing number of objects brought into low Earth orbit. In addition, it is necessary to consider the effects on the atmosphere from spacecraft re-entrya hot topic that ESA is also considering.
“Today, we lack information on many aspects when it comes to released materials and their subsequent effects on the atmosphere,” said Schulz.
Satellite reentries are a good opportunity to collect data with measurement campaigns, Schulz suggested. However, uncontrolled re-entries like ERS-2 are extremely difficult to observe, he said, because the level of uncertainty about where the satellite actually re-enters is so high.
“But controlled reentries provide great measurement opportunities,” said Schulz, “which should be targeted in the future!”
