ISRO to launch record 104 satellites on Feb 15

http://www.kaumudi.com/innerpage1.php?newsid=87911

by option_greek • 9 years ago

144 38 9 years 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?

trothamel3• 9 years 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• 9 years ago

This is exactly what is done to spread the satellites in their orbits.

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

jccooper• 9 years 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_dhaliwal2• 9 years ago

So released individually / batches over the course of multiple burns at the upper stage. An animation would be cool.

colechristensen• 9 years 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.

trothamel3• 9 years 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• 9 years ago

Surely the usa military or intelligence wouldn't be happy with that, right? Who would have access to this information?

wmf• 9 years 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• 9 years ago

Planet labs is a us company so they are subject to ITAR and the commerce control list.

jofer• 9 years 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.

sand500• 9 years ago

Don't forget that Planet just bought Terra Bella who has a fleet that can image at a higher resolution then Planet's

vinay427• 9 years 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

[2] http://indiabudget.nic.in/glance.asp

trothamel3• 9 years 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• 9 years ago

Does that include entitlements?

swatkat2• 9 years 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-s...

Brochure: http://www.isro.gov.in/pslv-c37-cartosat-2-series-satellite/...

swatkat2• 9 years 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...

greglindahl2• 9 years ago

Plenty of photos at: https://spaceflightnow.com/2017/02/14/indian-rocket-set-to-p...

zump4• 9 years 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• 9 years 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

maxander• 9 years ago

One might counter that in a truly diverse and moreover free nation, a citizen should be allowed to identify as they please.

gojiberry• 9 years ago

And you must be one of em Trump voters

zump4• 9 years ago

Why can't someone sympathize and be well-wisher for the nation of their ancestors?

shripadk• 9 years ago

I'm sure these hyphenations exist in every part of the World. It's these hyphenations that make a Nation stronger IMHO. In India, we have Luso-Indians (or Portuguese Indians), Dano-Norwegian Indians, German-Indians, French-Indians, Chinese-Indians, Parsis (Persian-Indians) etc. who made India their home. We don't force them to call themselves only "Indian". Why would you want someone to sever their past and their rich cultural heritage just to prove their Patriotism? Isn't that against the very notion of a "Free country" / "Republic"? As long as the citizen is not involved in any anti-National activities (terrorism, hate speech, espionage, disdain/disrespect for the Country's laws etc.) there is no need to bring that citizen's loyalty under suspicion.

There is no measure with which one can "feel more sympathy" for their ancestral-country than the country for which they have accepted citizenship. "Feel more sympathy" for what? Would an adopted child "feel more sympathy" for it's biological parents than the parents that nurtured it?

linuxkerneldev• 9 years ago

"There is no room in this country for hyphenated Americanism."

That's an odd thing to say given our history of how we treated (and currently treat) the only truly non-hyphenated Americans: Native Americans.

arjie2• 9 years ago

What's stopping you? You should be eligible for Indian citizenship (or even hold on to the US Citizenship and get an OCI card).

Did you apply?

zump4• 9 years ago

OCI doesn't let you hold government positions.

_jgdh• 9 years ago

In case someone hasn't come across "ABCD" before, it means American Born Confused Desi. Desi means someone of Indian heritage from the word Desh (country).

homosaphien1• 9 years ago

desi = indian, pakistani, bangladeshi

ISRO to launch record 104 satellites on Feb 15

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