KH-11 spysat design revealed by NRO’s telescope gift to NASA (2012)
americaspace.com
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Opportunity cost. That budget might have been passed over, and we might not have gotten Hubble at all. We're lucky we got the discount.
Thinking ahead, it's not a bad idea to mix in many smaller budgeted projects, such as the Discovery and New Frontiers programs seek to accomplish.
The exam was three questions, answer one. I only vaguely remember the one I did work on, but I remember this question well because I remember thinking "holy cow there isn't enough info in this problem to answer it", and also that apparently I was wrong!
Operational ground interferometers have obtained 5 mas resolution, which corresponds to sub-mm resolution from an orbital platform.
You still have atmospheric turbulence, but do we know how to get around the naive diffraction limit.
[1] https://en.wikipedia.org/wiki/Angular_resolution#Explanation
angle = k (wavelength / diameter)
I too would be interested in knowing if this image is showing all we got, or because someone else looked at it and said "sure you can release it, we've got better than that anyway."
However, I do not know near enough about physics to say the above with any degree of confidence.
A much more common technique is adaptive optics. A wavefront sensor measures the incoming signal from a reference star (or laser guide star) and deforms the mirror to compensate. I wouldn't be surprised if adaptive optics is also used on spy satellites though I can't imagine what they would use for a reference.
As other commenters have mentioned, you are always going to be limited by the diffraction limit of the telescope, which is a function of the mirror size and wavelength.
True, but it is very popular in astrophotography.
Also, there are many recent advances in super-resolution imaging, compressive sensing, and sub-diffraction-limit pixels, often based on results from Donoho, Candes, and friends. Taking advantage of signal sparsity (i.e. that the set of physically possible signals is much smaller than the set of all possible signals, and physical systems have many constraints upon them) has led to a lot of surprising results over the past 15 years or so. Another approach that has yielded results is aperture synthesis, which has been applied to optical systems for at least the past 15 years. And in some certain circumstances for spysats, optical heterodyne detection can also be used to great effect.
> you are always going to be limited by the diffraction limit of the telescope
While the diffraction limit of a system is definitely a constraint, it's not as simple as this anymore.
[1] https://en.wikipedia.org/wiki/Narrabri_Stellar_Intensity_Int...
However, there has been a major push recently to circumvent the limitations of optically connecting the telescope arrays; there are a few different approaches, of which I'm not aware of any fatal flaws. Seems likely it's a matter of time and physics and engineering; very difficult, but achievable.
See for example: https://dspace.mit.edu/bitstream/handle/1721.1/51042/Tegmark...
All the orbits are well known (to all interested parties at least) so I'd assume a downwards pointing laser guide wouldn't be much of an issue.
There was a major announcement on Friday using just this technique: https://www.gemini.edu/pr/gemini-gets-lucky-and-takes-deep-d... It might become more popular now.
Are you suggesting it was ok for this pic to be released, and why?
Second, there is also value to letting your adversaries know what you are capable of. Just think of the hassle of hiding activities from a satellite like that - surely it takes a huge operational toll.
No matter what, it sounds to me like releasing the picture is within the presidential oversight. He was not naming spies or anything.
I used to have a neighbor who lived across from me in 1997 who was a designer of spy satellites, and i used to ask him questions about capabilities as he washed hid car and would wash the window in one direction for affirmative, another for negative.
he intimated they could literally read a license plate from orbit in 1997
Ah! Long ago I had a (then) gf who was a Gamma ray astronomer. For part of her PhD she worked at Livermore labs. I couldn't have lunch with her because the section she worked was classified.
I asked her about it and she said that she did astronomy, and there were a lot of amazing gamma ray physicists there, but they were worried that anybody who could build or operate such a telescope could probably turn it to point down, which they very much did not want.
I still wonder if she was pulling my leg.
I thought gamma rays were filtered out though the atmosphere.
AFAIR, it was thanks to such gamma ray detectors pointed down that we've accidentally discovered gamma ray bursts.
https://en.wikipedia.org/wiki/Vela_(satellite)#Role_of_Vela_...
There have been 4 new generations of imagery platforms since, up to the current MISTY system that started launching in 1990.
I mean, we saw what the current capability was last year, and it that didn't seem like it's hugely better than the picture they put in the article.
Imagine having a big enough sensor and lens array to be able to see every individual boat in the Strait of Hormuz and track them all in real time. Or being able to pinpoint a spot on the planet and over the course of multiple passes by different birds, be able to construct a photo realistic 3D model of an oil refinery for a SEAL team to walk through in VR.
Great reading here: https://www.theverge.com/2019/7/31/20746926/sentient-nationa...
The guy said something like the Navy had 100% of AIS data going back a decade for us to work on, because of course they do.
(100 km^2) / (1 billion) = 0.1 m^2
I mean, it looks like the optical and near optical was the focus for spysats from the early days an up to the 80's. What are the frequency domain for the current sats? Can they listen to cellphone traffic, wifi-routers and bluetooth devices?
The capacity to target cellphones seems like a given. Being able to collect location and unique ids from wifi and bluetooth devices seems like a useful tool. Maybe even collect network traffic from and to specific networks and devices.
This means that essentially, power loss from distance is the only real issue power-wise. Which could be compensated for with large enough directional antennas. Next thing I'd be worried about is angular resolution. As I recall, lower wavelengths have more of an issue with diffraction. So it might be hard to design an antenna that is able to listen to a small enough area that you can distinguish individual devices.
Cause if you are getting a 100m resolution, that means receiving all BT transmissions in a 100m diameter circle. Doing that in a city would probably give to many overlapping signals to do anything with. It might be nice for tracking people in the wilderness though.
I have no idea how optimistic or pessimistic the 100m number is. I get the feeling that with phased array antenna's you could probably get higher resolutions that you'd think. I would guess it might be worth it if you want to trace signals out in the open (say, in middle-eastern deserts)
That resolution is inversely proportional to the aperture. So you could get it down by taking larger apertures. The best way to do that would be a phased antenna array, but that is computationally very expensive. It would be very cool though.
My questions are these:
NASA can barely keep JWST on a delayed schedule without massive cost overruns. What is another telescope good for? How many astronomers and support staff do we need in this industry? How do we measure and know that it's enough? What's the breakthrough that another telescope at the cost of $Bs would achieve? (and please be specific if anyone is going to reply, not just the old "because it's worth doing" argument -- that could justify any amount of spending)
These are the things you think about after you leave a field and are not beholden to it any more.
In any case it's not like NASA funds ground based telescopes, so I'm not sure what you would want to happen instead, just more rockets in space with blinkenlights to mess up the Rubin frames?
2. Machine time for researchers (I don't know how congested Hubble is but humanity could use more than a single telescope)
3. Redundancy in case JWST goes up in flames and we're left without a space telescope
There are 2 instruments. The coronagraph instrument (“WFIRST-CGI”) is a high contrast imaging test bed. If we want to have a technology path to image exoplanets, we need to test and improve the tech we have for masking the starlight of a target star, while allowing us to see the reflected light from a nearby exoplanet.
For earth like exoplanets, this is a 10^10 brightness difference. WFIRST will hopefully get us to 10^8. To get there, you need deformable mirrors, wavefront sensing, and active control.
We will also be able to get coarsely binned spectra from WFIRST. Spectra (in general — I’m not sure if WFIRST will get there) would allow us to detect presence of water absorption features in the reflected light. Eventually, we might be able to sense the oxygen A and B bands, which would indicate non-equilibrium chemistry.
My understanding is that WFIRST is more of a replacement for Hubble as it slowly dies (or suddenly dies at the end of a fiscal year due to $$$). However compared to both JWST and Hubble, it has a much higher field of view (the example that NASA gave at one point is that took the Hubble several years to survey the Andromeda Galaxy in IR. WFIRST could do that same job in a few hours). This has a lot of benefits if you want to do things like look for exoplanets. WFIRST will of course be very expensive, but for a number of reasons it is unlikely that it will be even close to the cost of JWST (like JWST it will be going to the L2 Lagrange point, but it won't have to make as many design compromises as JWST to get there)
The last decadal survey of astronomers[1] determined that WFIRST was a #1 priority because:
"...WFIRST will settle fundamental questions about the nature of dark energy, the discovery of which was one of the greatest achievements of U.S. telescopes in recent years. It will employ three distinct techniques—measurements of weak gravitational lensing, supernova distances, and baryon acoustic oscillations— to determine the effect of dark energy on the evolution of the universe. An equally important outcome will be to open up a new frontier of exoplanet studies by monitoring a large sample of stars in the central bulge of the Milky Way for changes in brightness due to microlensing by intervening solar systems. This census, combined with that made by the Kepler mission, will determine how common Earth-like planets are over a wide range of orbital parameters. It will also, in guest investigator mode, survey our galaxy and other nearby galaxies to answer key questions about their formation and structure, and the data it obtains will provide fundamental constraints on how galaxies grow. The telescope exploits the important work done by the joint DOE/NASA design team... and expands its scientific reach. WFIRST is based on mature technologies with technical risk that is medium low and has medium cost and schedule risk... WFIRST will complement the targeted infrared observations of the James Webb Space Telescope. The small field of view of JWST would render it incapable of carrying out the prime WFIRST program of dark energy and exoplanet studies, even if it were used exclusively for this task. The recommended schedule has a launch data of 2020 with a 5-year baseline mission. An extended 10-year mission could improve the statistical results and further broaden the science program. The European Space Agency (ESA) is considering an M-class proposal, called Euclid, with related goals. Collaboration on a combined mission with the United States playing a leading role should be considered so long as the committee’s recommended science program is preserved and overall cost savings result."
>How many astronomers and support staff do we need in this industry?
I'm going to be honest, this comes across as a bit of a loaded question. Obviously we don't "need" any astronomers at all (or most scientists for that matter). But more theoretical research can still have tremendous payoffs. I'm a big fan a letter[2] that a paperclip'd director at NASA Marshall wrote to a nun in Zambia who asked why the US spends billions going to the moon while children on Earth starve to death.
>How do we measure and know that it's enough?
I don't think humanity will reach a point in any scientific endeavor where we decide that it's enough and we don't need to understand any more. I suppose it would be when we have a complete understanding of the entire universe.
[1]: https://science.nasa.gov/astrophysics/special-events/astro20...
[2]: https://lettersofnote.com/2012/08/06/why-explore-space/
My questions are sparked very much by having departed the field and being able to look back more objectively (I think) than someone who's advocating from the position of needing the funding. I'm very familiar with the granting and budgeting process in astro.
So I actually have the goal of trying to help astronomers really think about how to justify their existence to the taxpayers who support them. Because most arguments are so "soft" that they could justify any $ amount of spending on astronomy, telescopes, students, postdocs, professors. And you can be pretty sure that anyone working in the field feels that the money is worth it -- and how can someone object? Or as in other replies, people will ask, why are you against fundamental science or some BS like that.
If you don't have any hard metrics to point to that some level is needed, what defense do you have against being cut, or on the other hand letting budgets run wild by the people who benefit from the employment?
One really famous professor in the field told me his belief was that "the current goal of astronomy research is to employ astronomers". How do we refute that?
On #1, how do we get a signal from the astronomy community that a certain research finding is of value? (and all the cost that went into it?) Everything is "worth it" from the typical point of view of astronomers. Even the 10th paper of the single halo white dwarf star luminosity function is "worth it"? Really? Or did it only justify the spending on that space telescope with UV capabilities because the money was already spent? I know it's unpleasant to crap on someone's research topic, but is it all worth it?
On #2, how many astronomers, telescope support astronomers, staff scientists, Northrup Grumman engineers, data archive specialists, etc etc etc are really needed? I guess it goes back to whether the science being done is worth it. But the people in those positions will find endless ways to justify their need to exist.
I suppose astronomy does have one big benefit -- you can quantify the popular appeal of it by how many people watch shows about astronomy, swipe right on astronomy Instagram posts, etc. But whether we need another multi-billion $ telescope to keep that going?
I frequently have my doubts, having left.
While I'm sure there's plenty of waste, I think that's just a fact of life. A positive way to think of it is that the 10th paper on white dwarf luminosity is just ensuring that previous work is reproducible :)
Even if someone takes the absolute most jaded view that it's all just a big federal jobs program, I think you could make the argument that it beats throwing more billions at the military industrial complex (of course there's plenty of synergies, like these 2 mirrors)
I simply try to combat the intellectually lazy position that some people fall back on, that any questioning of scientific merit (or resource intensiveness) is an affront to the whole thing and cannot be done. It's usually stated by people who have never had to do it, or don't know how.
This is an assumption but you're probably from the US since you used the "justify taxpayers money" catchphrase that's so overused as FUD for the spending narrative over there. So how about these:
https://en.wikipedia.org/wiki/Military_budget_of_the_United_...
Are they worth it? What are they good for? How many generals and support staff do you need? How do you measure and know it's enough? What's the breakthrough another plane, ship, tank, spy tech, drone at the cost of 700B to 1T per year would achieve? (and please be specific if you're going to reply, not the old "because it's worth doing" argument -- that could justify any amount of spending)
I think there are worthier things you should have opinions about than science spending because you seem very worried about the worthiness of it all. The worthiness of scientific progress and discovery? Should every paper be worthy? Must everything be immediately right and world changing? I'm surprised why someone that claims to have been in the field needs some sort of instant gratification for scientific work since that's rarely how science works. Not many cutting edge scientific breakthroughs can be said to have been "worth it" immediately. Sometimes it takes years, decades or even centuries for us to actually figure out the true value of some discoveries. We should never stop building or financing science or scientific experiments and we should never say that "it's enough", that's just nonsense.
Assume there is limited money to spend things on. How do you decide how to spend that money? Because using your arguments, you could spend all the money on astronomy and that would fine.
If it makes you feel any better...
I left fundamental particle physics for EE, since that's a lot more employable and it turns out being a particle physics experimentalist actually involves a pretty heavy EE load anyway. As part of my refocus I ended up doing all the EE work for a NIH- and DoD-funded medical research effort. This is a very different area of science than physics or astrophysics!
And it's, uh, mostly all garbage. An optimist might be happy if Sturgeon's Law applied and only 90% of it is crap. I could just as well say that the only goal of biomedical research is to employ biomedical researchers. So much time and money was wasted on research that was hyperspecialized or somehow just trivial, and didn't appear to be of any use beyond writing more grants and papers for the next generation of the lab's students. (And that's not even counting the animal research. I won't get involved in that stuff personally; that's not because I'm fundamentally opposed or anything, but because I've seen just how little is really learned from most such programs.)
And now I'm a consulting EE fully in the private sector. And guess what? Most projects that my company gets involved in are similarly doomed, right from the start.
I guess I'm trying to say a few things here:
1. I hear you. Oh, man, do I hear you.
2. At least astronomy gets what it pays for. Medical research sure doesn't!
3. Research has gotten hard. Long gone are the days when you could literally look through a handheld telescope or microscope and make a major discovery. Now discoveries are made by massive, interdisciplinary teams, and the teams are only getting larger. But the structure of research organizations has not evolved to meet the new reality, for many disparate reasons. (Case in point: Nobels still only go to three people, maximum.)
4. Similar budgeting and planning problems affect the entire economy. (And no, I personally don't believe central planning is the answer.) At some level, keeping us all busy kind of seems to be the point of it all.
5. If you want to see a similar soul-search, the thread the other day about building a new collider should show you the HEP people going through the same thing. (Though the interest-boredom product on that one didn't manage to exceed my threshold, so I didn't go through it.)
6. If universal basic income frees up enough the time of enough specialists, that could be really awesome for research. I'd love to build a telescope (again...)! And if I didn't have to worry about putting the proverbial food on my table, it would be fantastic to do that. But, alas, I fear that any specialist worth having is one who could find lucrative employment easily enough, even in an enviroment of UBI.
7. Seriously, don't feel too bad about yourself, telescopes are awesome! From both a science and engineering point of view. There are way worse things society could and would have spent that money on.
And you're right, compared to other industries/fields, astronomy gets a lot of bang for its buck and definitely produces a lot of good along the way. Most people end up leaving astronomy at some point (sooner than they thought), but go on to good things in other fields.
Remember the dinosaurs only died because they didn't have rockets, telescopes and nukes.
Multi-messenger astronomy[1] seems to be the next big thing.
Will we lose out if we don't have a good optical telescope "up there"? Or is the current crop of gamma/x-ray and IR satellite telescopes coupled with ground-based optical telescopes good enough?
I understand adaptive optics and such has drastically improved the capabilities of ground-based telescopes, but for MMA (to hijack the acronym) are there any advantages of a space-based optical telescope?
Neither will go to space. They are late-70s early-80s spy sats. This was a technology transfer so NASA could learn how NRO solved specific challenges they faced.
There was talk at the time about one of them being sent up in 2024, but that hasn't even been discussed seriously in the last 8 years.
Two years ago they issued the first production contracts, targeting a delivery date of 2025. Now we are looking at putting 50 year old parts in to space, at best.
Starship has a 10 meter fairing, so far less folding. It also can lift 5 times the mass of the Ariane 5, which would allow including heavier and tougher materials for the sunscreen (which has already torn once in testing), far more fuel for station keeping to extend its ten year life span by decades.
Even better, Starships 10 meter fairing would allow launch an actual 6.5 meter mirror instead of one built out of 18 smaller segments. The reduction in complexity is immense.
Lastly, Starship makes a JWST style observatory serviceable, even a million miles out at Earths L2 Lagrange point. That in itself makes for a longer life span, and regular upgrades, simplifying design decisions even more.
Also, given that a SpaceX sat dish is supposed to be the size of a pizza box which means incredibly hard to spot, it will open truly free (it will still be under the control/influence of the US government, though) Internet access worldwide... this is going to have a massive impact on China, North Korea and other countries where Internet freedom is severely restricted.