A solar gravitational lens will be humanity's most powerful telescope (2022)

The most complete plan for this was proposed by JPL's Slava Turyshev and team. It has been selected for Phase III of NASA Innovative Advanced Concepts. [0]

> In 2020, Turyshev presented his idea of Direct Multi-pixel Imaging and Spectroscopy of an Exoplanet with a Solar Gravitational Lens Mission. The lens could reconstruct the exoplanet image with ~25 km-scale surface resolution in 6 months of integration time, enough to see surface features and signs of habitability. His proposal was selected for the Phase III of the NASA Innovative Advanced Concepts. Turyshev proposes to use realistic-sized solar sails (~16 vanes of 10^3 m^2) to achieve the needed high velocity at perihelion (~150 km/sec), reaching 547 AU in 17 years.

> In 2023, a team of scientists led by Turychev proposed the Sundiver concept,[1] whereby a solar sail craft can serve as a modular platform for various instruments and missions, including rendezvous with other Sundivers for resupply, in a variety of different self-sustaining orbits reaching velocities of ~5-10 AU/yr.

Here is an interview with him laying out the entire plan.[2] It is the most interesting interview that I have seen in years, possibly ever.

[0] https://en.wikipedia.org/wiki/Slava_Turyshev#Work

[1] https://www2.mpia-hd.mpg.de/~calj/sundiver.pdf

[2] https://www.youtube.com/watch?v=lqzJewjZUkk

A 6 month integration time is going to generate massive amounts of data. How do they intend to receive all this back from 500 AU away?

Well, one single long exposure would literally generate a regular sized image. Though I do guess they’ll be doing multiple exposures if only to avoid saturating their dynamic range.

Does anyone know what a typical number of acquired frames is for a space telescope?

The computer onboard likely merges everything into a final image in space?

Sure, it would discard a lot of data / noise, and would send a preview over first, but like with the Pluto probe, they do want to get as much data as possible, as an image is only a representation thereof.

Orbiting instruments typically transmit raw instruments data blocked into lines or segments that are are each surrounded by checksums.

It might be compressed for transmission, but raw data (warts and all) is king .. once it's "processed" and raw data is discarded .. there's no recovering the raw.

Years later raw data can be reprocessed with new algorithms, faster processes and combined with other sources to create "better" processed images.

Onboard hardware errors (eg: the historic Hubble Telescope erros) can be "corrected" later on the ground with an elaborate backpropagated trandfer function that optimally "fixes" the error, etc.

Data errors (spikes in cell values, glitches from cosmic rays, etc) can be combed out of the raw in post .. if smart people have access to the raw.

Baking processing into on board instrument processing prior to transmission isn't a good procedure.

You could store all the data on the satellite, upload new code to process it differently, and download the resulting image. Then, the communications link just has to handle code (several MB up) and images (several MB down) instead of petabytes of data.

The launch mass of a petabyte of SSD is under 10 kg. I don't know if it would survive 17 years of space radiation though.

Well, you could.

I don't think I'd do that.

Ignoring the failure modes of a petabyte of SSD spending decades in deep space, what kinds of things are difficult and|or impossible if you were to

> store all the data on the satellite, upload new code to process it differently, and download the resulting image

?

Stop. For whatever reason, he has people call him Slava and does not correct them when they do so.

The Wikipedia article uses the name "Slava". His homepage on JPL website too (https://science.jpl.nasa.gov/people/turyshev/) I opened a random paper of his from arxiv and there too he uses "Slava".

Would it be possible that Mr. Turyshev uses that name as his preferred name (at least when writing in English) and that we should just respect his decision?

This decision is forced by it being hard for most English speakers to pronounce Vyacheslav.

>For whatever reason

The reason is that you won't bother to pronounce Vyacheslav so Russians have to use a short version of their name.

Sure, but is it his decision to make, and if yes - are we ok to respect it?

I'm from a slavic country myself and my name is almost impossible to pronounce correctly in English - but I continue to use it anyway. If he wanted to do that, he could have done it.

No, they don't have to - they are chosing to. To pretend otherwise is to say they don't have agency in this, which they do.

Even if somebody puts a gun to your head and orders you to change your name, you'd still have a choice and it would be your decision what to do. That's not much of an argument though.

No one put a gun to his head though. Discomfort of English speakers isn't enough reason to not use your real name if that's your preference. Again, speaking from experience.

Many Chinese (speaking) students in the US pick an English language name like “William” or “Wendy” because they know people they meet will struggle with a name which could be several short words with unfamiliar vowels and consonants and tone that matters.

People would want to avoid awkward situation and talk to you (or about you) less.

That's not quite the same as having a gun to your head. Again, I have a slavic name that's extremely difficult to English speakers and I live in the UK - no one is forcing me to change it. I understand some people chose to change their name so it's "easier" for English speakers - and I respect that choice. But let's not pretend that Mr Turyshev was "forced" to change his name - he wasn't.

Of course - and I support their choice. People struggle with my name every day and I could change it to make it easier for English speakers - but I don't think that's quite the same as being "forced" to change it.

I won't bother? But you don't know me?

Did you mean that English speakers don't pronounce Russian names the way Russians do?

Ask your local Russian to pronounce rural Worcestershire the way that English speakers do.

Your typical Russian speaker cannot. Is it that they aren't "bothering"? The idea is absurd. Let people approximate foreign names in their own tongue. Or, if the way that they naturally pronounce something is truly atrocious, give them a name that is easier to pronounce.

Or watch this fellow give foreign pronunciation his best shot: https://youtu.be/fKGoVefhtMQ Absurd, right?

Just as a thought experiment, would it be viable to send up an array of traditional hard drives? Arrange them all for use as reaction wheels, then spin them up to persist/de-stage data while changing/maintaining targets.

Probably worse than sending up well-shielded flash, but I don't think the Seagate/WD warranty expressly forbids this usage.

But this wouldn’t be in orbit; it would be in what NASA calls “deep space”, which relies on the Deep Space Network [1]. The DSN is severely bandwidth constrained, due primarily to a lack of ground antennas. Indeed, for instruments that are located outside Earth’s orbit (e.g. SOHO, which is at Sun-Earth L1 [2]), bandwidth is often a limiting constraint in the design.

My understanding is that some newer instruments do both compress and select data to be downloaded (i.e. prioritizing signal over noise), and that there is more and more consideration of on-board processing for future missions, as well as possibly introducing the capability within DSN itself to prioritize which instruments get bandwidth based on scientific value of their data.

Source: A presentation from people at NASA Heliophysics last week, where this very topic came up.

[1]: < https://www.nasa.gov/communicating-with-missions/dsn/> [2]: < https://science.nasa.gov/mission/soho/>

Sure, but do you refuse to use the names those people give? This takes away their agency. It is their call, not yours.

From the interview linked, it sounds like the current plan doesn't involve the DSN at all: they're effectively out of transmission range past a certain point, and the transmission back is optical, using a big earth or space-based telescope. Which is one of the scary things he mentioned: they're going to be entirely autonomous when collecting the data.

"Which is one of the scary things he mentioned: they're going to be entirely autonomous when collecting the data."

With no way to send commands to the decices?

Okay, that was about as rude on my part as ordering me to stop was on yours. My apologies.

But the point is that most people won't bother to google the pronunciation, listen to it and make an effort to repeat close enough. By the way, Dr. Turyshev's name is the easy part, the surname is the real challenge)

My name is "Pavel", and usually ask Americans to put the accent on the second syllable - which is incorrect, but they can't pronounce my name correctly anyway when they put the accent on the first syllable, and it sounds more wrong to me than the way I prefer to have it pronounced.

Apologies to all the other Pavels out there; I've been training everyone I've met to pronounce it wrong. But it's the way I prefer to be addressed.

It can also be annoying to run the 15-minute gauntlet of "but how do you really pronounce it", and you end up having to play dialect coach.

Going by an easy-to-pronounce name is much less aggravating.

Engrave it on a hair and coilgun it towards a receiver?

Sadly ,the last reference I see to this project is from 2022, from his own CV on his JPL profile page. What happens after stage 3 with NIAC? Is there even a stage 4, or does it need to get selected by some committee or something?

Sounds like we need to drop little relay nodes along the way to build the first SpaceNet

Now I'm curious what the _right_ pronunciation is!

The DSN is a radio network. In its present form, this is going to be ineffective for receiving a meaningful amount of imagery data from signals emitted by a lightweight space probe at 500AU. At ~150AU the current 25-70m dishes are getting less than 40 bits per second from Voyager 1.

Instead, we would use lasers with a far superior gain to what radio communication is capable of. The divergence on even a decent pocket laser pointer diode is less than 0.1 degree. This is a gain of 10*log10(41,253/(0.1*0.1)) = 66 degrees. Launch telescopes of modest size can increase this further. Then receiver telescopes fitted with narrowband filters can hone in on that laser signal.

> "First, transmitted beams from optical telescopes are far more slender than their radio counterparts owing to the high gain of optical telescopes (150 dB for the Keck Telescope versus 70 dB for Arecibo)." - https://www.princeton.edu/~willman/observatory/oseti/bioast9...

You can look it up on Youtube.

*Kerbnet

There was a massive 8% JPL layoff earlier in the year with a vauge 'uncertain upcoming budget' justification, perhaps affected a lot of plans. I don't have any inside info though.

I bet you're talking about his name because you have nothing to contribute to the topic at hand which is solar gravitational lens based telescopes.

Which is understandable as it is a very esoteric topic. But if you don't feel comfortable talking about a subject that doesn't mean that you should change the subject to one that you do feel comfortable with.

People come to Hacker News to see experts talk about these esoteric ideas and you ruin that when you derail the conversation into something relatable out of discomfort.

NASA and SpaceX should start architecting a Deep Space Network 2.0 relying on more space based relays so that we do need to rely on giant ground based antennae.

Put a relay at the Lagrange point.

Russians when speaking Russian have no obligation to pronounce my name the way that I do, given that it apparently has sounds that are not in Russian.

I don't think people have that obligation when the name has foreign sounds in it whatever language they're speaking.

The economics really don’t work out.

Stick a relay at the midpoint between earth / Voyager 1 so it gets a signal that’s 4x as strong. Unfortunately that’s still really weak so it needs a huge dish, and orbital mechanics means it can’s stay in that position.

We’re better off sending out probes that send stronger signals and just build huge ground based systems. At least until space based manufacturing becomes practical.

PS: Where relays make sense is for probes on the surface of a planet etc communicating with something in orbit which then sends signals to earth.

Where did the word 'obligation' appear from?

Introducing BLEO rendezvous elements for "resupply" into a mission with such wild dV scope and no landers, imposes some extreme constraints. I don't understand why you would do that unless solar sails as he understands them are extremely scale-dependent (like atmospheric flight is scale-dependent).

I learned this doing engineering trades on the Aldrin cycler idea; Ultimately it doesn't add much to a mission because getting there and getting back into the transfer sacrifices more than you could really hope to gain. You're likely better off just launching what you need attached to everything else at the Earth escape burn.

I'm curious about the Aldrin Cycler analysis. Isn't the whole point of the "castle" to house travelers and life support system in a larger habitable space during the long travel, independently of the cargo required for mars that's carried on a different, cheaper trajectory?

It's been a few years, and my memory isn't perfect, but...

Life support for a manned Mars missions runs maybe ten tons per person on the low end. That's mostly in shelf-stable packaged food; I used 6 tons in my estimate. Metabolizing food generates excess CO2 + H2O; elaborate ECLSS systems can crack this for extra oxygen and filter the water for further consumption and sanitation. This food dominates mission payload mass. It's heavier than the rest of the habitat put together. You have to put it to good use - line the interior of the hull with it and it serves as radiation shielding for the journey. You could try getting the CO2 + H2O back into hydrocarbon-lox fuel if you like, but that's going to make a fragile critical path for getting home.

The base hardware for Mars and the people for Mars are going on basically the same Hohmann transfer, and they're using it because it's the cheapest way. There are faster ways involving the help of Venus' gravity well, but they're only SLIGHTLY faster, they burn a lot more fuel, and more importantly they only occur briefly every few years. A more rapid direct transfer is possible at the cost of enormous amounts of fuel, but the purpose of that transfer is a 'flags and footprints' mission where you save about a third of your 3-year mission time at the cost of reducing your exploration and ISRU time window from a year to weeks. "Opposition class mission" vs "Conjunction class mission".

Nobody said that it's the same, but the logic of the argument is the same.

You lost the bet. I've been following his solar gravitational lens project since the 'Direct Multipixel Imaging and Spectroscopy of an Exoplanet with a Solar Gravity Lens Mission' [0] paper came out.

What you were betting? You farm, hopefully?

[0] https://arxiv.org/abs/2002.11871

Perhaps you did not realize that asserting "It's Vyacheslav" and complaining that people do not "bother" to google "proper pronunciation" and "practice" until "good enough" strongly implies obligation? If not, it does. Disagree or not, let's agree to let this go. Feel free to have the last word. I will read it carefully.

Of course it doesn't.

That's great! So talk about that stuff instead of bikeshedding what people should call him.