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| The old technology that keeps space missions alive |
For decades, some of the most famous space missions have been exploring and exploring our solar system. These include two Voyager expeditions. However, the technology that helps these campaigns continue may be different than you expect.
It was June 4, 1996, at the European Spaceport in French Guiana.
Europe's four identical cluster satellites took more than 10 years to design and build, but all of them turned into fireballs and were destroyed in just 39 seconds.
Their debris fell on the jungles of South America as the Ariane-5 rocket veered off course. The dignitaries who had earlier been outside enjoying champagne in their galleries were taken back inside to avoid being injured by the falling debris.
The disaster was apparently one of the biggest failures of the European Space Agency (ESA). But within a few months, work had begun on an alternative mission, Cluster-2.
Designed to investigate the interaction between the magnetosphere, or solar wind, and the magnetic bubble surrounding the Earth, Cluster-2 is one of the most successful and longest-lasting science missions to date. A
These satellites (named Rumba, Salsa, Samba, and Tango) have just completed 23 years in orbit and have recently celebrated their achievement.
"The mission was designed to last only three years," said Bruno Sousa, the cluster's mission operations manager at the European Space Operations Center (ESOC) in Darmstadt, Germany. There is a very enthusiastic group of scientists working on this mission. Some of them are waiting for its end so that they can enjoy their retirement.
Cluster-2 is one of the many missions that are still operational today and it is due to the skill of the engineering and science teams that they have overcome their shortcomings and solved problems through near-catastrophic failures. The challenge of maintaining the spacecraft came after controllers briefly lost contact with Voyager 2.
The twin Voyager probes, launched nearly 46 years ago in 1977, are still sending data from outside the solar system.
When I checked with NASA, they told me that the spacecraft is still being controlled from the same gray cubicle I visited in 2017. This cubicle is an addition to the Jet Propulsion Lab (JPL). There was a homemade cardboard sign with a sign reading: 'Mission Critical Hardware - Please Do Not Touch.'
The setup there will be familiar to cluster mission controllers, who had to deal with 20th-century ground control software built on an older operating system.
"We developed a complex setup and we have modern Linux servers running in a virtual environment with emulators of older operating systems," said Bruno Sosa. And the people who are running the software are part of the launch team who will retire when the mission is over."
Energy or electricity or power has also been an issue. The cluster satellites are charged with solar energy to provide electricity, but twice a year they pass into Earth's shadow and need batteries to keep them going.
"Batteries were designed to last only five years and by the sixth year they started to lose capacity," said Bruno Sosa. Then they cracked and eventually leaked and eventually became completely unusable.”
The solution was to turn off the satellites' power when they reached the Earth's shadow and then send signals to restart them in automatic mode. This is like doing a factory reset twice a year for the cluster. In fact, when it comes to spacecraft maintenance, its manufacturers are often asked to work on it.
Take, for example, the 10-meter-long Esa KXMM-Newton telescope. The telescope, built by Airbus, was designed to investigate X-ray emission from distant galaxies, and the giant telescope has been observing black holes for 24 years. It observed the birth and death of stars and has helped change our understanding of the hidden universe. But since the tenth year of his mission, he has seen the effects of age.
Like many satellites, XMM-Newton has thrusters to keep it moving and wheels to keep it stable. Powered by solar panels, these wheels spin rapidly and generate a force that causes their orbiters to rotate in the opposite direction. The telescope was designed to operate with three wheels while keeping the fourth as a backup. But like an old computer hard drive, after a decade it began to have trouble moving and its components began to wear out.
Instead of waiting until the reaction wheels were completely disabled, mission controllers moved the fourth wheelsEnabled but now they are running all wheels at slow speed.
Patrick Chapman, a UK-based Airbus engineer who has worked on XMM-Newton since 1995, explains: 'We developed the detailed algorithms and designed the software for it and then launched it on the spacecraft in 2013. Uploaded on.
"It is still healthy and we are also saving fuel," he added.
It took several months to fix the defect and save the telescope, but sometimes time is not an option.
On September 22, 2021, at half past ten in the morning, alarms started ringing in the Integral Mission Control Room of the European Space Agency in Ekos. A reaction wheel on the 19-year-old gamma-ray observatory had stopped working, putting the satellite into safe mode, but worse, it was slowly spinning out of control. was
"We had a lot of alarms going off and only three hours of power left on the satellite," said Richard Southworth, the mission's operations manager.
"We were running out of power because it was spinning away from the sun," added Greta DeMarco, the spacecraft's operations engineer.
Southworth says he was lucky in part because 'it was early in the morning, we were all at work and I happened to be on a Zoom call with about 100 Airbus engineers so I could tell them about the glitch. '
DeMarco says that because the team needed time to tell the direction and speed of the satellite, "we decided to turn off the instruments."
"Batteries were dying and I knew if we had to spin one more time it could happen," Southworth says. At that time I was a bit disappointed.
Eventually, the team was able to adjust the speed of the other reaction wheels, despite the signal stalling due to rotation.
"That was the moment I thought, 'If it works, it's fine, or we're gone,'" says Southworth.
"After hours of hard work and effort with many people in this fight, we were able to get the satellite back under control," DeMarco says.
Integral has been working well since then. But what if your old spacecraft is 150 million kilometers from your world?
Launched in 2003, the European Space Agency's Mars Express spacecraft was designed to remain in Mars orbit for two years. Nearly 20 years later, the mission is still probing the atmosphere and has captured stunning images of the Martian surface, as well as acting as a relay for a series of NASA rovers.
Like their colleagues, controllers have had to deal with outdated computer systems. For example, after the spacecraft's computer malfunctioned, engineers developed a new way to load commands into the spacecraft's computer's 2 MB RAM memory. (Note that an iPhone 14 today starts at 128GB of memory, which is 64,000 times more memory.)
They also discovered that the original software for part of the onboard navigation system was running on Windows 98, which no one could find a password to unlock, and used bolt cutters to remove the hard drives. has been. But the biggest challenge came five years ago and it was again a mechanical failure that threatened to end the mission prematurely.
Mars Express is equipped with six gyroscopes to measure rotation. There are also two cameras known as star trackers that enable the spacecraft to determine its direction in space. But by 2017, it was clear that Gyros was failing.
Simon Wood, the spacecraft's operations engineer, said: "We reviewed the spacecraft's condition in a large meeting and concluded that it has two years left to operate. And it turned out to be a very depressing meeting.
Fortunately, the spacecraft was built on a standard design that was used in other missions, including the cometary explorer 'Rosetta'. Although Mars Express was never designed to operate without its gyros, Rosetta's software allowed its gyros to be turned off. So could they hack the code designed for Rosetta more than 20 years ago and make it work for the Mars Express?
"Most of our colleagues thought we were crazy because the idea that you would go inside the onboard software source code was almost unheard of," says Simon Wood. But we stuck to it.
In 2018, they prepared to upload software and launch the spacecraft again. "The spacecraft hadn't been relaunched for 12 years because of the cold, so there were risks," says Simon Wood. It is performing better than our expectations and now we have a mission to extend it till 2028.”
But another mission in Mars orbit has been operating even longer. NASA's Odyssey mission has completed 95,000 orbits and is the oldest spacecraft to orbit another planet.
Mission project scientist Geoffrey Platt says: 'I feel very lucky to have such a robust robot on Mars.' He calls the current phase a 'golden age' of Mars exploration. "The mission was expected to last only a few years, and it's exciting that it allows us to do unexpected science experiments, especially long-term monitoring of weather and climate on Mars," he says. I... It is really remarkable.
Platt has been working on Odyssey since it reached Mars orbit in 2001, but the current operations team at JPL in Pasadena has only been working for the past 18 months. This team has received the baton of years of wisdom from the old team.
Mission Manager Jared Call is responsible for keeping the spacecraft going as long as possible. Ideally responsible for outlasting their European Space Agency competitor or better yet partner. "I don't know of any competition [with Mars Express], but if there is, I hope to win," says Jared Call, laughing.
Eventually, both spacecraft will run out of fuel in Mars orbit. "There is no fuel gauge on the spacecraft," says Call. There are probably three parts to the wisdom of propellant formulation. Two parts are calculations and one part is engineering and physics.
But no matter how skillfully the mission controllers work, all missions must eventually come to an end. Except maybe one. The Voyager spacecraft will continue its journey for millions of years with messages from Earth on a golden disc, our legacy to the universe long after we're gone.