A solar probe on a mission to take the closest pictures of the sun ever will pass incredibly close to Earth today, but debris from the recent Russian anti-satellite missile test will make the visit more risky and unpredictable.
European Space Agency (ESA) Solar Orbiter the spacecraft will zoom only 460 kilometers above the Earth’s surface on Friday at. 23:30 EST (Saturday at 16:30 GMT). This close encounter, a maneuver called flyby, will help push the satellite closer to the sun so it can begin its scientific exploration of the star.
But on 15 Nov. anti-satellite missile test of Russia, which shattered the nearly 2-tonne obsolete Kosmos 1408 satellite, adds concern for the ground control teams, who have carefully plotted Solar Orbiter’s path to make it efficient and safe.
“The Solar Orbiter will fly through the most polluted areas around the Earth,” Andrea Accomazzo, ESA’s head of solar system and exploration, who oversees the overflight, told Space.com. “We run calculations where we compare the orbit of the Solar Orbiter with the orbits of all known space debris objects. The problem is that [Russian ASAT] The test took place so recently that there is only partial information about the waste it created. “
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As the $ 1.5 billion Solar Orbiter approaches Earth, operators are fine-tuning these calculations. So far, Accomazzo said, everything looks good. But in the case of a piece known space junk seems to be on a collision course with the precious sun explorers, operators would perform a last-minute maneuver to guide the spacecraft through a safer zone. This maneuver, Accomazzo said, would change the altitude of Solar Orbiter’s closest approach to Earth by about 12 miles (20 km). Although it may seem insignificant, such an adjustment would make the bypass less efficient for its purpose – to tighten the Solar Orbiter’s path around the sun using the Earth’s gravity.
“It would slightly change the parameters of the gravity assistance maneuver,” Accomazzo said. “Later we will have to make a correction using the propellant on board the Solar Orbiter.”
Waste from the ASAT test is only a small part of the problem with the solar probe. ESA estimates that there are currently some 36,500 pieces of space debris larger than 4 inches (10 centimeters) storming around the Earth at incredible speeds (the Russian test created only about 1,500 of these). These can at least be tracked by ground-based radars and therefore avoided. In addition, there are about 1 million fragments between 0.4 inches and 4 inches (1 to 10 cm) across and a staggering 330 million that are smaller than 0.4 inches (1 cm) but larger than 0.04 inches (1 millimeter). These fragments are mostly invisible, but each of them can destroy or significantly damage a satellite.
In August 2016, a fragment of space junk about 0.04 inches (1 mm) in size smashed through a solar panel on the European Earth-observing Copernicus Sentinel-1A satellite, creating a 16-inch (40 cm) wide hole. The ground control team managed to make up for the loss of power, and the mission continues successfully to this day, Accomazzo said. But the result could have been much more serious.
“If this particle had hit the main body of the spacecraft, it could have destroyed its built-in computer,” Accomazzo said. “Without the built-in computer, the spacecraft is pretty much dead. Or it could have hit the propellant tank. And if it’s a mission that depends on propulsion, if you start leaking, then so be it.”
Unlike Sentinel 1A and thousands of other spacecraft that live their entire lives in the highly polluted low orbit of Earth, the area of space up to an altitude of 600 miles (1,000 km), the Solar Orbiter will only be in the danger zone for about two hours. One hour before it is closest to Earth, the satellite will glide through the geostationary ring, orbiting at an altitude of 22,000 miles (36,000 km), where satellites appear suspended over a fixed location on Earth. This region is populated by radio, telecommunications and weather forecast satellites and also contains a lot of clutter.
The Solar Orbiter will then dive straight through the most cluttered area in space, the low-orbit area of the Earth between 250 and 500 miles (400 and 800 km) above the planet’s surface, Accomazzo said. The spacecraft will pass just above the orbit International Room Station and exit the Earth’s vicinity and cross the geostationary ring again one hour after the nearest approach.
Accomazzo previously oversaw three ground flights of perhaps the most famous ESA spacecraft – the comet fighter Rosetta. He says that although the risk of these briefly visited spacecraft is relatively low, maneuvers that depend on the gravity of our planet have become more challenging over the past decade.
“The three Rosetta Earth overflights took place in 2005, 2007 and 2009,” Accomazzo said. “They were all at a higher altitude where there are fewer things. But it is certainly true that there is much more waste now than there was then.”
Hopefully the Solar Orbiter will wave goodbye to Earth unscathed. Although it will not capture any images of the planet, scientists working with its sensitive instruments hope it will make measurements of the Earth’s magnetic field and solar wind near the planet, ESA said. in a statement.
Most importantly, this bypass will give the Solar Orbiter the last kick it needs to reach its target distance from the sun. The big moment comes in about four months, in March 2022, when the solar observer will pass at a distance of only 34 million miles (50 million km) from the surface of the sun (about a third of the distance between Sun and Earth). This will be the closest a spacecraft with a camera has approached the sun. NASAs Park solar probe flies much closer, but the environment it is in is so hot that no existing imaging technology could take pictures of the sun from so close.
Scientists have high expectations for Solar Orbiter’s next big moment. Already during its first close approach, which took the probe about 48 million miles (77 million km) from the sun, the Solar Orbiter discovered new phenomena on the star’s surface, miniature solar eruptions called campfire. These campfires may be behind one of the biggest mysteries in the sun’s behavior, namely extreme warming of its corona.
But even then, Solar Orbiter’s journey will only have just begun. Accomazzo said the spacecraft will continue to visit Venus at regular intervals to use its gravity to tilt its orbit out of the ecliptic plane, the plane in which the planets orbit. This will allow the spacecraft’s sensitive image cameras to take the first close – ups ever of the star’s poles. And there, researchers expect many more new discoveries.
Solar Orbiter, launched in February 2020, just before the start of the COVID 19 pandemic. The mission went through the most sensitive the commissioning phase during the first COVID lockdown in Europe with control teams operating under limited socially distant conditions.
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