Meet the Lady Who Makes the James Webb Area Telescope Work




“Give me a telescope, and I can provide you with one thing good to do with it,” says Jane Rigby, an astrophysicist at NASA’s Goddard Area Flight Middle who serves because the company’s operations undertaking scientist for the $10-billion James Webb Area Telescope, the biggest and strongest off-world observatory but constructed by humankind. Over the course of her profession, Rigby has used lots of the world’s premier ground- and space-based astronomical amenities—and she or he is helming considered one of Webb’s many “early launch science” campaigns front-loaded for its first 12 months of observations, using the telescope to check star formation in galaxies throughout eons of cosmic time. However her most important work with Webb is to work along with her workforce to make sure everybody lucky sufficient to make use of it might probably do “one thing good,” by taking care of the complete breadth of scientific investigations the telescope will carry out for researchers across the globe throughout its deliberate five-year main mission. That is no small job: For these hoping to squeeze as a lot science as attainable out of this one-of-a-kind observatory, every second of Webb’s time is valuable—and Rigby oversees the schedule.

Ever since Webb launched on Christmas Day of 2021, she and her colleagues have been working nonstop to arrange the observatory to ship breakthrough discoveries in regards to the universe’s first galaxies, close by exoplanets and rather more. Now, with its mirrors and devices prepared and its inaugural batch of science photos and information set for imminent launch, Webb’s revolutionary research are poised to really start. Scientific American spoke with Rigby in regards to the teamwork it takes to function Webb, the observatory’s unsure longevity and the fragile job of maximizing returns on a $10-billion funding within the largest and greatest telescope within the identified universe.

[An edited transcript of the interview follows.]

Issues are wanting good for Webb, aren’t they? We’re on the verge of seeing the telescope’s first science photos, its efficiency has exceeded expectations throughout commissioning, and its voyage to deep area left it with sufficient surplus propellant to proceed operations into the 2040s—a few years past its “nominal” mission lifetime. How exceptional to suppose we would get a lot “further” trip of this factor that’s required a long time of regular, diligent work and $10 billion, this superb facility that will in some respects be the only largest funding ever made in astrophysics. So I needed to speak to you about how the undertaking is defending this funding, and the way it’s going to maximise the juice for the squeeze, so to talk.

Issues are wanting nice, completely. This telescope actually just isn’t solely pretty much as good as we promised—in some ways, it’s higher. And I’m pleased to speak about all features of juice-making. Like everybody else on the workforce I’m excited to unveil Webb’s first science photos. This would be the first time we really put some “juice” out, and from there everybody can decide for themselves how candy it’s. I like this “juice” metaphor—as long as we’re not speaking about steroids.

Wait, however isn’t Webb “Hubble on steroids”? Sorry, dangerous joke.

It could take lots of steroids, really. Webb is 100 occasions extra highly effective than current observatories.

Ha, okay. So that you’re Webb’s undertaking scientist for operations. Does that imply you’re making all of the juice?

Effectively, one of many issues a undertaking scientist does is act because the conscience for the science. This telescope was principally constructed by engineers and managers, however scientists needed to be within the loop, too, to make sure that it might probably do the science for which it’s being constructed. Now, as an “operations” undertaking scientist, meaning I fear about how we’re going to make use of the telescope—every thing from deciding on proposed observations to creating observing schedules, from working the telescope to getting the information again to Earth and eradicating all of the instrumental signatures. No matter it takes to get the science performed.

Proper. So, simply to be clear, you’re operations undertaking scientist, however that doesn’t imply you select the place Webb seems or who will get to make use of it.

There’s no “who you understand” inside observe. Most of Webb’s time is allotted via very aggressive peer evaluation. For Cycle 1 Common Observer applications, we enlisted a panel of 200 specialists—all digital due to COVID—to evaluation and rank greater than a thousand proposals from all around the world. The highest quarter of proposals had been chosen. That’s performed twin anonymously: reviewers don’t know who wrote the proposals, and the proposers don’t know who critiques them. We need to decide by the standard of the concepts. Meaning, as an illustration, it’s attainable for an autodidact from exterior academia to get time on Webb. You might dwell in a rustic that doesn’t essentially like our nation, or that didn’t do something to assist construct the telescope, and usually you possibly can nonetheless use it, proper? It’s an open competitors as a result of we wish the most effective concepts.

How do you juggle all of those “greatest” concepts, although, to determine which of them take precedence? Looks like a tough job.

This can be like explaining the distinction between constructing a juicer versus really utilizing it to make juice, seeing the place it will get jammed up, and fixing it.

So, first some fundamentals: Webb can level anyplace inside a 3rd of the sky on any given day. That restriction makes certain that the sunshield is all the time oriented in order that it blocks mild from the Earth, the Solar and the moon. That subject of observability precesses such that Webb can see 100% of the sky over the course of a 12 months. Realizing that, for any mounted goal (as in a single not whizzing across the photo voltaic system), we will calculate which and what number of days per 12 months Webb can see it. Targets within the airplane of our photo voltaic system can be found for about 60 days a 12 months. Targets out of the airplane (straight as much as the north or south poles of our photo voltaic system) can be found year-round. Targets in intermediate ecliptic latitudes fall between these extremes.

Some targets we have to observe at sure occasions. Like exoplanets at sure factors in orbit round their stars, or an exploding star, or another phenomenon that’s time-dependent.

There’s additionally a query of how darkish the sky is. For some targets and wavelengths, it issues so much whether or not you’re wanting via sizzling mud towards the Solar or colder mud additional out within the photo voltaic system. So for a given goal, how darkish the sky is for observing it varies seasonally. For some observations, we don’t actually care. But when we’re actually faint issues, then we need to schedule when the background sky is as darkish as attainable.

We additionally don’t need Webb to be idle. And, we have to get the information again to Earth. We discuss to Earth a couple of third of the time throughout regular science operations, with a gimbaled antenna we will level whereas we’re observing. The info price isn’t dangerous—about 30 megabits per second—however it’s slower than a cable modem, and there are 57 megapixels of reminiscence inside Webb’s devices. We handle that by asking customers to not be information hogs, and by doing lots of information compression.

We schedule the telescope by optimizing over all these constraints, to generate a household of acceptable options. We make a long-range plan, wherein for each remark, we assign possibly a month-long time slot the place it’s more likely to go. After which each seven to 10 days we’ll make an in depth schedule for that week—the batting order, so to talk. This course of is tailored from Hubble, which additionally has a lot of constraints, although Webb’s are fairly totally different than Hubble’s.

Corresponding to?

First off, for Hubble the Earth is in the way in which half the time. Hubble makes use of that point to slew to the following goal, and in any other case prepare. Webb doesn’t have that concern, because it’s in deep area. Meaning Webb can’t cover its slews behind the Earth like Hubble does. Webb is an enormous telescope, so it slews slower than the minute hand on a clock. So if you wish to flip it 180 levels, that takes most of an hour. So to make use of gendered language, scheduling is the basic “touring salesman” downside—how do you optimize a bunch of various “stops” to kind a route? We hyperlink up a bunch of visits which are shut collectively within the sky to keep away from doing massive, time-consuming slews.

There’s one other method Webb and Hubble are totally different which is necessary for scheduling and caring for the telescope, and that’s momentum buildup. It seems that the truth that photons carry momentum units a restrict on the lifetime of the telescope. As a result of propellant is among the most important constraints on Webb’s lifetime, and momentum administration is considered one of Webb’s most important makes use of of propellant.

Might you unpack that for us a bit?

Photons placing Webb’s sunshield apply torque. Now, we might orient the sunshield to cancel out the torques—however we need to level the telescope at targets, not get the sunshield completely balanced by daylight. So the photons hit the sunshield, they apply torque, and Webb’s response wheels spin as much as counteract this impact and maintain the telescope pointed. However the response wheels can solely spin so quick. They often need to dump their angular momentum. In low-Earth orbit, Hubble simply {couples} the response wheels to the Earth’s magnetic subject to sluggish them down. That doesn’t work out in deep area, so as an alternative Webb fires thrusters to push towards the spin of the response wheels. We do these momentum dumps periodically, every time utilizing little propellant. However, as you talked about, at this stage now we have sufficient propellant to get into the 2040s, so Webb’s longevity is extra more likely to be restricted by how lengthy parts final…. Truthfully, although, it feels bizarre to be plotting the nursing-home days of this telescope when it’s nonetheless a new child simply opening its eyes!

You may not like this subsequent query, then: Assuming every thing else stays peachy, and propellant inevitably runs out, how will Webb die?

Wow, so we actually are speaking in regards to the dying of this factor. I virtually don’t need to speak about this; it feels untimely, as a result of it’s a brand-new telescope. It’s like speaking in regards to the dying of a child. If we’re speaking about being propellant-limited, as soon as that useful resource runs out, we’d be unable to regulate the pointing to make sure the photo voltaic panels all the time see the Solar and the telescope by no means sees it. Finally the photo voltaic panels would fall into shadow for lengthy sufficient that restoration can be unlikely. I suppose that may be like Webb’s final breath. That might be once we’d comprehend it was actually lifeless. However, once more, it’s arduous to know what precisely will occur to Webb in its twilight years because it’s a new child.

We’ve already been shocked, as an illustration, by a micrometeorite affect that had a higher than anticipated impact on one of many main mirror segments, and we’re actively finding out what such occasions would possibly imply for Webb’s ongoing optical efficiency. Micrometeorites are a reality of life in orbit that can step by step degrade the standard of the mirrors and the sunshield—and we’ve overengineered and in-built margins with that in thoughts—however was this a once-every-five-years occasion, and we simply obtained unfortunate, or are we going to be getting extra hits like this than we anticipated? We’re working to determine that out. I’m nonetheless planning for a protracted, fruitful mission, in fact.

Certainly. You already know, it does appear to be you and folks who work on Webb have, fairly fairly, shaped an emotional attachment to it. Has that made it more difficult to navigate all the assorted make-or-break moments within the telescope’s so-far-short life?

Effectively, the emotions change for every distinct part of Webb’s commissioning. In the course of the launch and within the first couple of weeks afterward once we had been doing main deployments, there have been a number of key days the place we knew we would lose the mission that day. We had been up entrance about that; NASA even made this video referred to as “29 Days on the Edge.” I attempted to strategy these days with fatalism: “If it doesn’t work, we don’t have a mission.” As one deployment after one other labored, I noticed I used to be going via the levels of grief. Largely bargaining: “Oh, let’s please simply get the secondary mirror out, I don’t even want the first mirror to unfold its two wings!”

Why the secondary mirror?

The phrase “secondary” makes it sound prefer it’s not that necessary, or a backup. However in a telescope, secondary simply means the sunshine hits it second, after the first. Webb’s main mirror is iconic and far bigger. However that 0.7-meter secondary is completely essential. If the secondary mirror deployment hadn’t labored, then the sunshine bouncing off that beautiful main mirror would fly out to area, misplaced endlessly, as an alternative of being collected in a science instrument. Even when the first mirror hadn’t totally unfolded, if we nonetheless had that secondary mirror, we’d have a functioning however degraded telescope. So when the secondary mirror deployed, completely, I noticed how a lot fear I had been holding onto, after engaged on this factor for the previous 11 years—and lots of my colleagues have labored on it longer.

We’re fortunately performed with these make-or-break moments, in addition to the “commissioning” part of intense choreography and testing. The telescope has cooled to its goal temperature, the optics are aligned, the science devices are prepared. We’ve been attending to know the precise telescope’s true efficiency in area, and with the primary science photos we’ll present not solely that Webb is working, however that it’s totally able to doing all of the superb science for which it was constructed. It’s an exquisite feeling.