Interview with Jane Rigby about scheduling James Webb's workload
“Give me a telescope, and I can come up with something good to do with it,” says Jane Rigby, an astrophysicist at NASA’s Goddard Space Flight Center who serves as the agency’s operations project scientist for the $10-billion James Webb Space Telescope, the largest and most powerful off-world observatory yet built by humankind.
Later in the interview she delves into the need for thrust for the JWTS, which I knew was a thing, but hearing the in-depth answer is absolutely fascinating
Photons striking Webb’s sunshield apply torque. Now, we could orient the sunshield to cancel out the torques—but we want to point the telescope at targets, not get the sunshield perfectly balanced by sunlight. So the photons hit the sunshield, they apply torque, and Webb’s reaction wheels spin up to counteract this effect and keep the telescope pointed. But the reaction wheels can only spin so fast. They occasionally have to dump their angular momentum. In low-Earth orbit, Hubble just couples the reaction wheels to the Earth’s magnetic field to slow them down. That doesn’t work out in deep space, so instead Webb fires thrusters to push against the spin of the reaction wheels. We do these momentum dumps periodically, each time using little propellant. But, as you mentioned, at this stage we have enough propellant to get into the 2040s, so Webb’s longevity is more likely to be limited by how long components last…. Honestly, though, it feels weird to be plotting the nursing-home days of this telescope when it’s still a newborn just opening its eyes!
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Astronomy Is About to Get Way More Exciting Because of the James Webb Telescope
For astronomers, being here on the cusp of a bold new understanding of things is like trying to fall asleep the night before Christmas. (They’re certainly less stressed out than they were on the actual night before Christmas, in 2021, in the hours before Webb launched to space on December 25.)
Next week’s lineup includes an assortment of subjects that are meant to demonstrate Webb’s range as an all-purpose space telescope that can show us the universe in infrared, a wavelength invisible to our eyes.
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There are more galaxies than even Carl Sagan imagined - Big Think
But when it comes to the number of galaxies that are actually out there, we’ve learned a number of important facts that have led us to revise that number upwards, and not just by a little bit. Our most detailed observations of the distant Universe, from the Hubble eXtreme Deep Field, gave us an estimate of 170 billion galaxies. A theoretical calculation from a few years ago — the first to account for galaxies too small, faint, and distant to be seen — put the estimate far higher: at 2 trillion. But even that estimate is too low. There ought to be at least 6 trillion, and perhaps more like 20 trillion, galaxies, if we’re ever able to count them all.
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First Six-star System Where All Six Stars Undergo Eclipses
If you have trouble visualizing how that would work, here, have an illustration from NASA:
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