Space weather in our solar system has been rather unsettled of late, and some of our tenacious robotic interplanetary explorers have been feeling the impact of the sun’s temper tantrums. The European Space Agency’s Venus Express orbiter suffered a particularly nasty solar sucker-punch, temporarily blinding one of its navigational systems.
The solar radiation hit Venus’ orbit on March 7 (Tuesday) after the sun had belched out a series of solar flares and coronal mass ejections (CMEs). This radiation uptick knocked-out Venus Express’ startracker cameras (including the backup camera), causing them to lose sight of stars the spacecraft uses to orient itself.
As described by Paolo Ferri, head of ESA’s solar and planetary mission operations, the loss of the spacecraft’s startracker is akin to trying to walk and find your way around with your eyes closed. “For a human being, the startrackers are the eyes and the gyroscopes are the ears,” he told SPACE.com. “When you close your eyes, you can go on for a while with your ears if you’re walking, but sooner or later you have to open your eyes and see where you are because the ears are not accurate enough.”
The gyroscopes on board spacecraft act like our inner ear — they maintain balance and orientation — but the startrackers (our eyes) are needed to find a point of reference. The point of reference used by the startrackers are the stars and constellations.
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Although the temporary loss of a startracker does occasionally happen, this event was more prolonged than usual. But ESA mission operators proudly announced on Friday that the instrument was back online. On Monday, the ESA Twitter feed confirmed the mission would recommence scientific operations imminently: “++ News from #Venusexpress team: star trackers stable over wk/end; all systems tested & ‘Go’ for return to full science 2night #solarflare”
Like the satellites that deliver cable TV and global positioning data in orbit around Earth, robotic missions sent to other planets in our solar system are vulnerable to the sun’s radiation. Sophisticated hardware and software are developed to mitigate the worst damage a solar storm can bring, but as Venus Express can attest, sometimes the sun can pack a very hard, and unexpected, punch.