6 ms·

ISRO to launch record 104 satellites on Feb 15

144 points by option_greek 10y ago

ajeet_dhaliwal 10y ago
Can someone with understanding of satellite launches explain to a layman how the satellites get into their respective orbits when launched together like this?
- trothamel 10y ago
  Well, most of the satellites will want to be in about the same orbit - the fairly common sun-synchronous orbit, that passes over the same spot on earth every day. They probably want to spread the satellites out over the orbit, though. I'm not sure if randomness would be enough to do this, but if not, they could probably control things a little bit, at least for the Dove satellites (88 of them). Since the Dove satellites can point themselves to take pictures, my guess is that they can also choose to point themselves either perpendicular or parallel to the orbital direction. Since there's a little bit of atmosphere left up there, over time that should be enough to intentionally spread the satellites out. This is just a guess, but I know similar techniques have been used in the past on satellites that were out of fuel - for example, Skylab.
  - breu 10y ago
    This is exactly what is done to spread the satellites in their orbits. https://support.planet.com/hc/en-us/articles/212641458-How-do-you-spread-your-satellites-out-after-launch- https://support.planet.com/hc/en-us/articles/212641458-How-d... This paper covers diff drag in more detail. https://arxiv.org/abs/1509.03270 https://arxiv.org/abs/1509.03270
- jccooper 10y ago
  If a satellite has its own maneuvering capabilities, it can change its orbit (somewhat). These are mostly nanosats and cannot do that, so they'll stay in closely-related orbits. Spring-loaded separation from the launch vehicle will give them some difference, which will be magnified over time. Some rideshare launches have multiple burns of the upper stage to put payloads in different orbits. The PSLV can do that, though I don't know if this one will.
  - ajeet_dhaliwal 10y ago
    So released individually / batches over the course of multiple burns at the upper stage. An animation would be cool.
- colechristensen 10y ago
  Either the last stage of the rocket is relit, the satellites can thrust themselves, or the small velocity they're released with over time will put the satellites in different orbits. A relit final stage can put satellites in significantly different orbits. Satellite thrusters can do a little but only small orbital changes. And just releasing over a period of time will result in each sat being released on the order of 1 m/s which is enough to keep them separated but in the same orbit.
trothamel 10y ago
88 of these are Planet Labs's Dove satellites, which are 4kg, 3U (10x10x30cm) satellites. From what I understand, the goal of these is to image the entire earth every day at 3-5 meter resolution.
- hak8or 10y ago
  Surely the usa military or intelligence wouldn't be happy with that, right? Who would have access to this information?
  - wmf 10y ago
    Planet Labs is a US company so presumably they have US government approval for their sats. Their resolution is really low by today's standards so their imagery may not be considered sensitive. Or maybe they just blur out the same things that every other satellite company blurs out.
  - walrus01 10y ago
    Planet labs is a us company so they are subject to ITAR and the commerce control list.
  - jofer 10y ago
    The US has surprisingly few restrictions on satellite imagery until you get below ~50cm resolution. Beyond a short list of nations/groups that the US has strict export controls with (e.g. N. Korea), there aren't any restrictions at all on who can be sold imagery. Other countries (e.g. Canada) actually have considerably more restrictions on collecting and selling imagery.
    - zackbloom 10y ago
      Is the resolution of commercial imaging products limited right now by law or tech?
      - sandworm101 10y ago
vinay427 10y ago
The ISRO 2016-2017 budget is approximately $1.1 billion USD [1]. The national budget is about $301 billion USD [2]. That means that ISRO constitutes approximately 0.37%. [1]: http://www.isro.gov.in/budget-glance http://www.isro.gov.in/budget-glance [2]: http://indiabudget.nic.in/glance.asp http://indiabudget.nic.in/glance.asp
- trothamel 10y ago
  For comparison, NASA is about 0.5% of the US budget. At the height of spending on Apollo in 1966, it was 4.4%.
  - mrfusion 10y ago
    Does that include entitlements?
    - toomuchtodo 10y ago
      Entitlements come directly out of payroll taxes, so it's not a legitimate comparison. You'd want to compare defense spending, as that is the largest spending item that comes from federal income tax receipts.
      - JumpCrisscross 10y ago
        > Entitlements come directly out of payroll taxes When the latter fail to cover the former, those entitlements will be paid out of income taxes. I don't think it's honest to lump out a preferred pool of spending like that. I could similarly claim all spending linked to corporate and capital gains taxes not be counted as part of the budget.
        toomuchtodo 10y ago
        I mean, we could argue about this all day, no (although, the income is separated logically, which is why I made my argument in parent comment; it would take Congressional effort to spend payroll tax income on non-entitlement spending)? Sure, federal tax receipts will be used to replenish social security and Medicare, but I'm fine with that. We can afford to cut defense spending back, as we spend more than the next 8 countries combined. That's our own money being squandered. http://www.politifact.com/truth-o-meter/statements/2016/jan/13/barack-obama/obama-us-spends-more-military-next-8-nations-combi/ http://www.politifact.com/truth-o-meter/statements/2016/jan/...
swatkat 10y ago
Payloads: Cartosat-2 Series INS-1A INS-1B 88xDove 8xLEMUR BGUSat Al-Farabi-1 PEASS DIDO-2 Nayif-1 Mission page: http://www.isro.gov.in/launcher/pslv-c37-cartosat-2-series-satellite http://www.isro.gov.in/launcher/pslv-c37-cartosat-2-series-s... Brochure: http://www.isro.gov.in/pslv-c37-cartosat-2-series-satellite/pslv-c37-brochure http://www.isro.gov.in/pslv-c37-cartosat-2-series-satellite/...
swatkat 10y ago
I am interested to know how all those payload are mounted on PSLV's payload adapter. Cartosat 2 Series is the primary payload, and remaining 103 satellites are co-passengers. Usually, PSLV mission brochures used to depict how payloads are mounted on its payload adapter. However, it isn't shown this time. a) Cartosat 2 Series - primary payload. b) 88xDove (88x3U CubeSats) - 22 QuadPack[1] deployers. c) 8xLEMUR (8x3U CubeSats) - 2 QuadPack deployers. d) BGUSat (3U CubeSat), PEASSS (3U CubeSat), DIDO-2 (3U CubeSat), Al-Farabi-1 (2U CubeSat), and Nayif-1 (1U CubeSat) - 1 QuadPack deployer. e) INS-1A and INS-1B are not in CubeSat format. So, they need to be mounted separately on payload adapter. So, we have a primary payload + 25 QuadPack deployers + 2 nano-sats. Hopefully we'll get some info during mission live broadcast on how these payloads are mounted on PSLV. [1] http://digitalcommons.usu.edu/cgi/viewcontent.cgi?filename=0&article=3161&context=smallsat&type=additional http://digitalcommons.usu.edu/cgi/viewcontent.cgi?filename=0...
- greglindahl 10y ago
  Plenty of photos at: https://spaceflightnow.com/2017/02/14/indian-rocket-set-to-place-104-satellites-in-orbit/ https://spaceflightnow.com/2017/02/14/indian-rocket-set-to-p...
zump 10y ago
ABCD here, wish I could work for ISRO. Would gladly move to a country where I don't even speak the language and get 10% salary.
- winter_blue 10y ago
  Your loyalty should lie with the United States, not the nation of your ancestors. This sort of ancestral-country-patriotism is not good. Let me quote Theodore Roosevelt: "There is no room in this country for hyphenated Americanism. When I refer to hyphenated Americans, I do not refer to naturalized Americans. Some of the very best Americans I have ever known were naturalized Americans, Americans born abroad. But a hyphenated American is not an American at all … The one absolutely certain way of bringing this nation to ruin, of preventing all possibility of its continuing to be a nation at all, would be to permit it to become a tangle of squabbling nationalities, an intricate knot of German-Americans, Irish-Americans, English-Americans, French-Americans, Scandinavian-Americans or Italian-Americans, each preserving its separate nationality, each at heart feeling more sympathy with Europeans of that nationality, than with the other citizens of the American Republic … There is no such thing as a hyphenated American who is a good American. The only man who is a good American is the man who is an American and nothing else." Source: https://en.wikipedia.org/wiki/Hyphenated_American https://en.wikipedia.org/wiki/Hyphenated_American
  - maxander 10y ago
    One might counter that in a truly diverse and moreover free nation, a citizen should be allowed to identify as they please.
  - gojiberry 10y ago
    And you must be one of em Trump voters
    - deleted 10y ago
      [deleted]
  - zump 10y ago

144 points by option_greek 10y ago

Can someone with understanding of satellite launches explain to a layman how the satellites get into their respective orbits when launched together like this?

trothamel 10y ago
Well, most of the satellites will want to be in about the same orbit - the fairly common sun-synchronous orbit, that passes over the same spot on earth every day. They probably want to spread the satellites out over the orbit, though. I'm not sure if randomness would be enough to do this, but if not, they could probably control things a little bit, at least for the Dove satellites (88 of them). Since the Dove satellites can point themselves to take pictures, my guess is that they can also choose to point themselves either perpendicular or parallel to the orbital direction. Since there's a little bit of atmosphere left up there, over time that should be enough to intentionally spread the satellites out. This is just a guess, but I know similar techniques have been used in the past on satellites that were out of fuel - for example, Skylab.
- breu 10y ago
  This is exactly what is done to spread the satellites in their orbits. https://support.planet.com/hc/en-us/articles/212641458-How-do-you-spread-your-satellites-out-after-launch- https://support.planet.com/hc/en-us/articles/212641458-How-d... This paper covers diff drag in more detail. https://arxiv.org/abs/1509.03270 https://arxiv.org/abs/1509.03270
jccooper 10y ago
If a satellite has its own maneuvering capabilities, it can change its orbit (somewhat). These are mostly nanosats and cannot do that, so they'll stay in closely-related orbits. Spring-loaded separation from the launch vehicle will give them some difference, which will be magnified over time. Some rideshare launches have multiple burns of the upper stage to put payloads in different orbits. The PSLV can do that, though I don't know if this one will.
- ajeet_dhaliwal 10y ago
  So released individually / batches over the course of multiple burns at the upper stage. An animation would be cool.
colechristensen 10y ago
Either the last stage of the rocket is relit, the satellites can thrust themselves, or the small velocity they're released with over time will put the satellites in different orbits. A relit final stage can put satellites in significantly different orbits. Satellite thrusters can do a little but only small orbital changes. And just releasing over a period of time will result in each sat being released on the order of 1 m/s which is enough to keep them separated but in the same orbit.

trothamel 10y ago

88 of these are Planet Labs's Dove satellites, which are 4kg, 3U (10x10x30cm) satellites. From what I understand, the goal of these is to image the entire earth every day at 3-5 meter resolution.

hak8or 10y ago
Surely the usa military or intelligence wouldn't be happy with that, right? Who would have access to this information?
- wmf 10y ago
  Planet Labs is a US company so presumably they have US government approval for their sats. Their resolution is really low by today's standards so their imagery may not be considered sensitive. Or maybe they just blur out the same things that every other satellite company blurs out.
- walrus01 10y ago
  Planet labs is a us company so they are subject to ITAR and the commerce control list.
- jofer 10y ago
  The US has surprisingly few restrictions on satellite imagery until you get below ~50cm resolution. Beyond a short list of nations/groups that the US has strict export controls with (e.g. N. Korea), there aren't any restrictions at all on who can be sold imagery. Other countries (e.g. Canada) actually have considerably more restrictions on collecting and selling imagery.
  - zackbloom 10y ago
    Is the resolution of commercial imaging products limited right now by law or tech?
    - sandworm101 10y ago

vinay427 10y ago

The ISRO 2016-2017 budget is approximately $1.1 billion USD [1]. The national budget is about $301 billion USD [2]. That means that ISRO constitutes approximately 0.37%. [1]: http://www.isro.gov.in/budget-glance http://www.isro.gov.in/budget-glance [2]: http://indiabudget.nic.in/glance.asp http://indiabudget.nic.in/glance.asp

trothamel 10y ago
For comparison, NASA is about 0.5% of the US budget. At the height of spending on Apollo in 1966, it was 4.4%.
- mrfusion 10y ago
  Does that include entitlements?
  - toomuchtodo 10y ago
    Entitlements come directly out of payroll taxes, so it's not a legitimate comparison. You'd want to compare defense spending, as that is the largest spending item that comes from federal income tax receipts.
    - JumpCrisscross 10y ago
      > Entitlements come directly out of payroll taxes When the latter fail to cover the former, those entitlements will be paid out of income taxes. I don't think it's honest to lump out a preferred pool of spending like that. I could similarly claim all spending linked to corporate and capital gains taxes not be counted as part of the budget.
      - toomuchtodo 10y ago
        I mean, we could argue about this all day, no (although, the income is separated logically, which is why I made my argument in parent comment; it would take Congressional effort to spend payroll tax income on non-entitlement spending)? Sure, federal tax receipts will be used to replenish social security and Medicare, but I'm fine with that. We can afford to cut defense spending back, as we spend more than the next 8 countries combined. That's our own money being squandered. http://www.politifact.com/truth-o-meter/statements/2016/jan/13/barack-obama/obama-us-spends-more-military-next-8-nations-combi/ http://www.politifact.com/truth-o-meter/statements/2016/jan/...

swatkat 10y ago

Payloads: Cartosat-2 Series INS-1A INS-1B 88xDove 8xLEMUR BGUSat Al-Farabi-1 PEASS DIDO-2 Nayif-1 Mission page: http://www.isro.gov.in/launcher/pslv-c37-cartosat-2-series-satellite http://www.isro.gov.in/launcher/pslv-c37-cartosat-2-series-s... Brochure: http://www.isro.gov.in/pslv-c37-cartosat-2-series-satellite/pslv-c37-brochure http://www.isro.gov.in/pslv-c37-cartosat-2-series-satellite/...

swatkat 10y ago

I am interested to know how all those payload are mounted on PSLV's payload adapter. Cartosat 2 Series is the primary payload, and remaining 103 satellites are co-passengers. Usually, PSLV mission brochures used to depict how payloads are mounted on its payload adapter. However, it isn't shown this time. a) Cartosat 2 Series - primary payload. b) 88xDove (88x3U CubeSats) - 22 QuadPack[1] deployers. c) 8xLEMUR (8x3U CubeSats) - 2 QuadPack deployers. d) BGUSat (3U CubeSat), PEASSS (3U CubeSat), DIDO-2 (3U CubeSat), Al-Farabi-1 (2U CubeSat), and Nayif-1 (1U CubeSat) - 1 QuadPack deployer. e) INS-1A and INS-1B are not in CubeSat format. So, they need to be mounted separately on payload adapter. So, we have a primary payload + 25 QuadPack deployers + 2 nano-sats. Hopefully we'll get some info during mission live broadcast on how these payloads are mounted on PSLV. [1] http://digitalcommons.usu.edu/cgi/viewcontent.cgi?filename=0&article=3161&context=smallsat&type=additional http://digitalcommons.usu.edu/cgi/viewcontent.cgi?filename=0...

greglindahl 10y ago
Plenty of photos at: https://spaceflightnow.com/2017/02/14/indian-rocket-set-to-place-104-satellites-in-orbit/ https://spaceflightnow.com/2017/02/14/indian-rocket-set-to-p...

zump 10y ago

ABCD here, wish I could work for ISRO. Would gladly move to a country where I don't even speak the language and get 10% salary.

winter_blue 10y ago
Your loyalty should lie with the United States, not the nation of your ancestors. This sort of ancestral-country-patriotism is not good. Let me quote Theodore Roosevelt: "There is no room in this country for hyphenated Americanism. When I refer to hyphenated Americans, I do not refer to naturalized Americans. Some of the very best Americans I have ever known were naturalized Americans, Americans born abroad. But a hyphenated American is not an American at all … The one absolutely certain way of bringing this nation to ruin, of preventing all possibility of its continuing to be a nation at all, would be to permit it to become a tangle of squabbling nationalities, an intricate knot of German-Americans, Irish-Americans, English-Americans, French-Americans, Scandinavian-Americans or Italian-Americans, each preserving its separate nationality, each at heart feeling more sympathy with Europeans of that nationality, than with the other citizens of the American Republic … There is no such thing as a hyphenated American who is a good American. The only man who is a good American is the man who is an American and nothing else." Source: https://en.wikipedia.org/wiki/Hyphenated_American https://en.wikipedia.org/wiki/Hyphenated_American
- maxander 10y ago
  One might counter that in a truly diverse and moreover free nation, a citizen should be allowed to identify as they please.
- gojiberry 10y ago
  And you must be one of em Trump voters
  - deleted 10y ago
    [deleted]
- zump 10y ago