Quote from: A_M_Swallow on 05/06/2012 06:39 pmQuote from: BrightLight on 05/06/2012 06:23 pmQuote from: Robotbeat on 05/06/2012 06:17 pmQuote from: BrightLight on 05/06/2012 05:51 pmThe number one issue for an imaging interferometer is the time of acquisition, all the imagers must have good synchronized clocks - at least at nanosecond time scales, these exist and are not terribly hard to operate in space (invar mounts, rad hardened, insulated, thermal stabilized), but without this minimum capability all else is moot.GPS can be used to assist time synchronization. Though obviously that's a little more tricky in orbit.Absolutely, but GPS NEMA strings are around 2 Hz, and even with WAAS, you have millisecond timing, one needs atomic clock scale timing on each platform.Can you have the master clock on one satellite and derive the time from a control signal at the other satellites?If you bounce the control signal back distance and time delay can be measured.That technique is used on some coordinated assets but has not been used for interferometers as far as I know. Master clocks - one on the master platform and one on the ground receive side would have to trigger the sensors - how do you get thenm to trigger at the same time?
Quote from: BrightLight on 05/06/2012 06:23 pmQuote from: Robotbeat on 05/06/2012 06:17 pmQuote from: BrightLight on 05/06/2012 05:51 pmThe number one issue for an imaging interferometer is the time of acquisition, all the imagers must have good synchronized clocks - at least at nanosecond time scales, these exist and are not terribly hard to operate in space (invar mounts, rad hardened, insulated, thermal stabilized), but without this minimum capability all else is moot.GPS can be used to assist time synchronization. Though obviously that's a little more tricky in orbit.Absolutely, but GPS NEMA strings are around 2 Hz, and even with WAAS, you have millisecond timing, one needs atomic clock scale timing on each platform.Can you have the master clock on one satellite and derive the time from a control signal at the other satellites?If you bounce the control signal back distance and time delay can be measured.
Quote from: Robotbeat on 05/06/2012 06:17 pmQuote from: BrightLight on 05/06/2012 05:51 pmThe number one issue for an imaging interferometer is the time of acquisition, all the imagers must have good synchronized clocks - at least at nanosecond time scales, these exist and are not terribly hard to operate in space (invar mounts, rad hardened, insulated, thermal stabilized), but without this minimum capability all else is moot.GPS can be used to assist time synchronization. Though obviously that's a little more tricky in orbit.Absolutely, but GPS NEMA strings are around 2 Hz, and even with WAAS, you have millisecond timing, one needs atomic clock scale timing on each platform.
Quote from: BrightLight on 05/06/2012 05:51 pmThe number one issue for an imaging interferometer is the time of acquisition, all the imagers must have good synchronized clocks - at least at nanosecond time scales, these exist and are not terribly hard to operate in space (invar mounts, rad hardened, insulated, thermal stabilized), but without this minimum capability all else is moot.GPS can be used to assist time synchronization. Though obviously that's a little more tricky in orbit.
The number one issue for an imaging interferometer is the time of acquisition, all the imagers must have good synchronized clocks - at least at nanosecond time scales, these exist and are not terribly hard to operate in space (invar mounts, rad hardened, insulated, thermal stabilized), but without this minimum capability all else is moot.
Quote from: douglas100 on 05/06/2012 04:23 pmHow is interferometry going to make them a lot of money?It could make them some money. (But I don't think they'll do traditional interferometry if they do it at all.)
How is interferometry going to make them a lot of money?
A larger issue is that the Arkyd system represents a major technical advance in itself, and there are probably ways for the system to generate revenues outside the telescope business.Like, building cheap satellites for other customers.
One of the items is that they will be the first commercial customer of a high speed data communications capability, the in space laser comm to be hosted on the large GEO data comm sats for use like a TDRSS.
Quote from: oldAtlas_Eguy on 05/07/2012 05:49 pmOne of the items is that they will be the first commercial customer of a high speed data communications capability, the in space laser comm to be hosted on the large GEO data comm sats for use like a TDRSS.Yes, this is an area (forgetting the interferometry stuff) where they could advance the art. Long range optical communication will allow them to bypass a potential DSN bottleneck and get a high downlink rate from a "fleet" of their spacecraft during the asteroid inspection phase of their plan.
Quote from: douglas100 on 05/07/2012 08:55 pmQuote from: oldAtlas_Eguy on 05/07/2012 05:49 pmOne of the items is that they will be the first commercial customer of a high speed data communications capability, the in space laser comm to be hosted on the large GEO data comm sats for use like a TDRSS.Yes, this is an area (forgetting the interferometry stuff) where they could advance the art. Long range optical communication will allow them to bypass a potential DSN bottleneck and get a high downlink rate from a "fleet" of their spacecraft during the asteroid inspection phase of their plan.Development of a satellite buss with this capability might also gain them significant revenue, through providing it to a second party that would then add customization and sensors. Building a larger quantity of the satellite buss's would reduce the cost per unit for PR's own sats.
Like, building cheap satellites for other customers.
Quote from: Blackjax on 05/05/2012 10:48 pmQuote from: douglas100 on 05/05/2012 08:43 pmThat was partially my point: that if they wish to do interferometry the hardware will be much more expensive. However, as you say, they have considerable financial wherewithal. What makes you so confident that there is no (relatively) low cost way they might come up with to solve this problem?(please take this as a genuine question, and not disagreement disguised as a question, I know absolutely nothing about the technical challenges involved and I am curious)No, that's a reasonable question. Seehttp://proceedings.aip.org/resource/2/apcpcs/387/1/245_1?isAuthorized=noFor an optical interferometer to work, the distance between the elements (the telescopes in this case) has to be controlled to something of the order of the size of the wavelength of light. This has been done for ground astronomical instruments like Keck or VLT. As far as I know, this level of accuracy has never been achieved by free flying spacecraft. I believe it will be very expensive to develop. I don't think telescopes in LEO can station keep to this accuracy because there are to many perturbing forces, like drag and gravity gradient.
Quote from: douglas100 on 05/05/2012 08:43 pmThat was partially my point: that if they wish to do interferometry the hardware will be much more expensive. However, as you say, they have considerable financial wherewithal. What makes you so confident that there is no (relatively) low cost way they might come up with to solve this problem?(please take this as a genuine question, and not disagreement disguised as a question, I know absolutely nothing about the technical challenges involved and I am curious)
That was partially my point: that if they wish to do interferometry the hardware will be much more expensive. However, as you say, they have considerable financial wherewithal.
What is the reason they must be free flying rather than on some sort of expandable or extendable structure?
But is there any indication that they're planning to do something like that?
In general yes. You guys really need to read Diamandis's book to frame your perspectives on PR. Ties back to the undertakings of singularity university (such as 3d printing) and exponential technologies in general. Reading his book is why I think PR is aimed at optical interferometry.
Is this competition for PR, or something else?Grunts Get Spy Sats of Their Ownhttp://www.wired.com/dangerroom/tag/kestrel-eye/Kestrel Eye, which is being built by IntelliTech Microsystems, grew out of a Darpa project for a twenty-pound imaging satellite equipped with a ten-inch telescope. The downlink system can send back two images a second, each covering an area five miles square with a resolution of five feet. That does not count as high-resolution in the reconnaissance world, and it’s only about a tenth of what can be delivered by Keyhole-12. But it’s enough to identify individual building and vehicles. And that could be extremely helpful to the grunt on the ground.
