Author Topic: Planet Labs earth imaging satellites  (Read 91025 times)

Offline Silmfeanor

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #40 on: 02/11/2014 04:48 pm »
Koichi got good pictures.  :)
Confirmed :)   (This picture is from that second deployment).

@Astro_Wakata tweeted:

Congratulations on  the successful deploy of the satellites by the NanoRacks  CubeSat Deployer and Kibo robotics! pic.twitter.com/GsUzvC8NKO
Attached to my post is the high-res version of that. Can see quite a bit of detail (used the :orig tag on the url to get it )
« Last Edit: 02/11/2014 04:49 pm by Silmfeanor »

Offline pericynthion

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #41 on: 02/11/2014 05:28 pm »
All four in good health :)

Offline pericynthion

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #42 on: 02/11/2014 05:36 pm »
The satellites tumbled a little bit more than I expected, but it made for good visuals, as the setting sun highlighted different parts of them in sequence.

34.2 degrees per second.

Offline jongoff

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #43 on: 02/11/2014 07:47 pm »
Does anyone know of an estimate of the lifetime of these sattelites when launched from the ISS at around 410 km altitude?  It could be only a few months.

I've heard numbers in the 6-12 months for typical cubesats (varies a lot based on satellite density and density variations in the upper atmosphere).

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Offline InfraNut2

Re: Planet Labs nano-sat earth imaging satellites
« Reply #44 on: 02/11/2014 08:17 pm »
Does anyone know of an estimate of the lifetime of these sattelites when launched from the ISS at around 410 km altitude?  It could be only a few months.

I've heard numbers in the 6-12 months for typical cubesats (varies a lot based on satellite density and density variations in the upper atmosphere).

~Jon

I read that Planet Labs expected an orbital lifetime of up to around 2 years for these "dove" satellites.

From this SpaceNews article: http://www.spacenews.com/article/features/39297profile-chris-boshuizen-chief-technology-officer-planet-labs-inc

Quote
Q: Space station operates in a fairly low orbit. Will it limit the lifespan of your satellites?

A: Without an on-board propulsion system, their life will be fairly limited. Our [business] model is based on our ability to mass-produce satellites. Instead of building a more sophisticated satellite with a 10-year lifetime, we chose to build a much simpler spacecraft with a design life of a couple of years and replenish the constellation.

Clark Lindsey said 1-2 years but I do not know if he had additional sources for that or just extrapolated from the same source.

Quote
The Planet Labs strategy is that they can obtain high resolution images from small aperture nanosats by flying in a much lower orbit than the large aperture imaging satellites. This will reduce their lifetime to a year or two but the launch capability provided by the ISS allows them to replace lost satellites easily and at relatively low cost.

I thought that sounded longer that normal. Usually the lifetimes are more like jongoff says. Maybe these satellites are more dense than your typical cubesat...

edit: added source quotes

edit2: Just found out Dove-2 is 5.5kg. The Flock-1 doves should be at least that heavy, so they are indeed heavier than the usual cubesats, so that could explain their lifetime expectancy. It seems more common for some of the 3U cubesats to be extra heavy (and then usually the most ambitious ones). 1U cubesats are rarely heavier than 1.3kg--usually closer to 1kg.
« Last Edit: 02/11/2014 09:18 pm by InfraNut2 »

Offline jcm

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #45 on: 02/12/2014 05:37 am »
So when is the next deploy I wonder?
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Offline jcm

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #46 on: 02/12/2014 05:57 am »
... ISS Ustream showing the nanoracks deployer, so I wonder if a new deploy is planned for this evening.

The color scheme of the video does seem to indicate that ISS is orbiting Jupiter right now...
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Offline jcm

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #47 on: 02/12/2014 06:15 am »
Per ISS audio,  the third deploy at 0235 UTC Feb 12 failed to occur despite repeated commanding.
They will skip those sats for now and try the fourth deploy at a little after 0730 UTC, 15 min from now.
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Offline jcm

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #48 on: 02/12/2014 06:30 am »
Deploy delayed to 0822 UTC. Wish someone else was up to catch the actual time - I may be asleep by then
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Offline Robotbeat

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #49 on: 02/12/2014 06:32 am »
Skybox Imaging, one of the three companies mentioned in the article, provides "sub-meter" resolution imagery.


Yeah, although I haven't found anything specific. Some articles say "about a meter or less," but that's still somewhat vague. I also cannot find any specifics on their satellites. What are the dimensions and what is the diameter of their imaging mirror? It looks like the satellite may be about 80 cm tall and 60 cm on a side, and I would guess that puts the mirror diameter at 40-50 cm. Somebody could then plug that into the satellite altitude and get a decent guess at the resolution.

http://www.wired.com/wiredscience/2013/06/startup-skybox/
Easy peasy. 1.22*wavelength*altitude/aperturediameter

Altitudes from: http://uppsagd.files.wordpress.com/2012/03/fcc_exhibit-43_skysat-1.pdf

On one end: 1.22*400nm*450km/(50cm) = 44cm.
On the other: 1.22*600nm*637km/(40cm) = 117cm.

400nm is bluish. 600nm is reddish.
It should be noted that the /nominal/ altitude is supposed to be about 450km with a lifetime of about 2.5 years.

It seems reasonable to suggest a little less than 1m resolution.
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Offline jcm

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #50 on: 02/12/2014 07:38 am »
Two satellites deployed at 0830 UTC Feb 12.

OK, bedtime - seems like the only way we are going to find out about these deployments is for people to watch the
ISS stream, so I hope others will join in here.
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Offline Artyom.

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #51 on: 02/12/2014 11:21 am »
The Small Satellite Orbital Deployer (SSOD), in the grasp of the Kibo laboratory robotic arm, is photographed by an Expedition 38 crew member on the International Space Station as it deploys a set of NanoRacks CubeSats. The CubeSats program contains a variety of experiments such as Earth observations and advanced electronics testing.

Offline eeergo

Re: Planet Labs nano-sat earth imaging satellites
« Reply #52 on: 02/12/2014 11:05 pm »
Was it planned that one of them deployed with the aperture already uncovered?
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Offline Comga

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #53 on: 02/12/2014 11:44 pm »
Was it planned that one of them deployed with the aperture already uncovered?

From the first to the second image it is seen that the aperture cover opened as the satellite was being deployed.
It is also seen that this satellite is rotating faster than the one behind it, whose aperture remains closed. 
It seems unlikely that both conditions are intentional.  Either they are all supposed to open on deployment, or to all remain closed for a while.   Something appears to have gone awry.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline pericynthion

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #54 on: 02/12/2014 11:57 pm »
Actually, the aperture cover deployment sequence was designed that way (I agree that it is a bit surprising, but there were good reasons).  The covers on the "rear" satellites open later, on a timer.  All have successfully opened.
« Last Edit: 02/13/2014 12:03 am by pericynthion »

Offline Lar

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #55 on: 02/13/2014 01:54 am »
Actually, the aperture cover deployment sequence was designed that way (I agree that it is a bit surprising, but there were good reasons).  The covers on the "rear" satellites open later, on a timer.  All have successfully opened.

Thanks for that clarification!

Reading through the posts in order it wasn't clear to me where things stood, was a deployment pair "skipped" and then the next pair worked? Or did the skipped pair eventually deploy as well. What is the tally as of now? Any info on a recovery plan for that pair? (bringing the dispenser inside and fiddling with it?)
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Offline jcm

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #56 on: 02/13/2014 05:02 am »
The tally is 6, the third deployment pair was skipped (and may be tried again tonight if I understand correctly).
The fourth pair has been cataloged as 39518 and 39519 so it looks as if Space-Track is leaving a gap (39516 and 39517) to backfill for the third pair when they are eventually deployed.
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Offline Comga

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #57 on: 02/13/2014 06:03 am »
Actually, the aperture cover deployment sequence was designed that way (I agree that it is a bit surprising, but there were good reasons).  The covers on the "rear" satellites open later, on a timer.  All have successfully opened.

So much for simple logic.
Practice is always more complex than theory.
Thank you for correcting my error.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline jcm

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #58 on: 02/13/2014 07:29 am »

7th and 8th satellites were deployed at 0820 UTC Feb 13.  These may be the ones that got stuck earlier.
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Offline Danderman

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Re: Planet Labs nano-sat earth imaging satellites
« Reply #59 on: 02/13/2014 05:45 pm »
Getting back to the issue of populating the planes, I would imagine that by deploying the satellites in sequence over 48 hours, they would be more or less distributed evenly around the globe.


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