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#700
by
aero
on 17 Dec, 2013 04:33
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Does anyone know what the actual payload mass was for the Cassiope launch? what was it?
If not, I've searched and found the satellite masses but not the mass of any ancillary parts.
Cassiope - 481 kg
CU Sat - 40.82 kg
DANDE - 50 kg
DOPACS - 4.5 kg
Does anyone know what the mass of the payload adapter? What was it?
I know the trajectory of the first stage up to MECO pretty well from repeatedly viewing the launch (available on livestream), pausing and recording the data as it is given. Using this stage 1 trajectory I conclude that the F9.1 could not reach LEO with 13,150 kg though it can with other trajectories. I'm trying to simulate the boost-back so knowing the payload would help determine the fuel available for that function.
Cassiope went to a 300 x 1,500 km x 80 deg orbit from Vandenberg AFB. The 13.15 tonne figure is given for a 185 km x 28.5 deg orbit from Cape Canaveral, where extra delta-v is provided by the Earth's rotation. Payload from Vandenberg toward a near-polar orbit will be much less - and the higher altitude will take away even more lifting capability. Falcon 9 v1.1 is probably only able to lift 9 tonnes or less to the Cassiope orbit, assuming that the advertised capabilities are accurate.
- Ed Kyle
Thanks Ed - of course that was my mistake. Using Cassiope numbers from a FLA launch site proves nothing.
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#701
by
kevin-rf
on 17 Dec, 2013 11:42
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Don't you also incur a penalty for Cassiope's use of a single upper stage burn vs. double upper stage burn trajectory.
Though to be fair, if the payload needs the extra boost, there is no reason they would not use a two burn profile.
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#702
by
rpapo
on 17 Dec, 2013 13:12
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Don't you also incur a penalty for Cassiope's use of a single upper stage burn vs. double upper stage burn trajectory.
Though to be fair, if the payload needs the extra boost, there is no reason they would not use a two burn profile.
The problem with having the Falcon second stage do three burns (LEO injection, raise apogee to GEO, raise perigee to GEO also) is the 5-6 hours spent between the second and third orbit. Some of the engine lines froze in the CASSIOPE mission in less than an hour. The SES launch handled the half-hour wait fine, but 5-6 hours is a lot longer. On top of that is the issue of keeping the LOX tank stable during that time.
If I'm not mistaken, those considerations were why they invented the current technique, the one used in the SES launch.
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#703
by
Jim
on 17 Dec, 2013 13:47
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The problem with having the Falcon second stage do three burns (LEO injection, raise apogee to GEO, raise perigee to GEO also) is the 5-6 hours spent between the second and third orbit. Some of the engine lines froze in the CASSIOPE mission in less than an hour. The SES launch handled the half-hour wait fine, but 5-6 hours is a lot longer. On top of that is the issue of keeping the LOX tank stable during that time.
If I'm not mistaken, those considerations were why they invented the current technique, the one used in the SES launch.
They did not invent any technical. They just performed the standard two burn protocol for launching commercial comsats, which has been used by Atlas, Delta and Ariane for more than 40 years. The 3 burn protocol is a DOD standard for some of its spacecraft (which don't have perigee boost systems).
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#704
by
rpapo
on 17 Dec, 2013 13:56
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I know they didn't invent this technique for this mission, and that the technique has been around for a very long time. But it wasn't there in the beginning (the 60s), and that was where I was coming from. I wasn't fully aware of the current technique until I saw it happening with the SES launch. It flew beneath my personal radar in the years since Apollo. I wasn't paying attention to the techniques of GEO satellite launching, being distracted by moon launches, space shuttles and interplanetary probes...
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#705
by
edkyle99
on 17 Dec, 2013 14:01
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Don't you also incur a penalty for Cassiope's use of a single upper stage burn vs. double upper stage burn trajectory.
Though to be fair, if the payload needs the extra boost, there is no reason they would not use a two burn profile.
In this case - a 300 x 1,500 km elliptical low earth orbit - the penalty isn't substantial assuming insertion is done at perigee. A two-burn mission would have a bigger advantage if the goal was a 1,500 km circular orbit.
- Ed Kyle
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#706
by
Jim
on 17 Dec, 2013 14:32
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I know they didn't invent this technique for this mission, and that the technique has been around for a very long time. But it wasn't there in the beginning (the 60s), and that was where I was coming from. I wasn't fully aware of the current technique until I saw it happening with the SES launch. It flew beneath my personal radar in the years since Apollo. I wasn't paying attention to the techniques of GEO satellite launching, being distracted by moon launches, space shuttles and interplanetary probes...
The "techniques of GEO satellite launching" were developed from "moon launches, space shuttles and interplanetary probes" in the 60's. The two burns were done for Surveyor in 1967 by Atlas Centaur and for Apollo 8 in 1968.
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#707
by
rpapo
on 17 Dec, 2013 16:05
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The "techniques of GEO satellite launching" were developed from "moon launches, space shuttles and interplanetary probes" in the 60's. The two burns were done for Surveyor in 1967 by Atlas Centaur and for Apollo 8 in 1968.
That's not the same thing, and you know it. Both of those launches were translunar injection, which is not the same thing as coming up with a streamlined, efficient technique for launching a satellite to geosynchronous orbit. They didn't get really creative with trajectories and orbits until a few years later. The 70s saw a huge improvement in the imagination and capability of the trajectory designers, with the Voyager and Pioneer probes, and it hasn't stopped since. I don't know that anybody in the 60s would have ever dreamed of what they have been doing around Saturn these past ten years with the Cassini probe, or what they did in the 90s with the Galileo probe around Jupiter.
But this is getting rather off-topic...
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#708
by
Jim
on 17 Dec, 2013 18:04
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The "techniques of GEO satellite launching" were developed from "moon launches, space shuttles and interplanetary probes" in the 60's. The two burns were done for Surveyor in 1967 by Atlas Centaur and for Apollo 8 in 1968.
That's not the same thing, and you know it. Both of those launches were translunar injection, which is not the same thing as coming up with a streamlined, efficient technique for launching a satellite to geosynchronous orbit.
Wrong, it is the exact same thing and I do know that. TLI is just a little more velocity than a SSTO injection. The same processes are used in designing the trajectory for both. There is no "streamlined, efficient technique for launching a satellite to geosynchronous orbit"
bi- elliptic transfer orbit and SSTO are old (1934 was when the bi- elliptic transfer orbit was published)
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#709
by
Jim
on 17 Dec, 2013 18:12
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I don't know that anybody in the 60s would have ever dreamed of what they have been doing around Saturn these past ten years with the Cassini probe, or what they did in the 90s with the Galileo probe around Jupiter.
Yes, they did. The sling shot maneuver was proposed in 1961 and used by Mariner 10 in 1973 (which means it was designed in the 60's).
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#710
by
rpapo
on 17 Dec, 2013 18:17
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While I will agree that there is no essential difference between the second burn of Falcon and that of the other rockets you referred to, what I was originally referring to was the notion (long ago) that the final insertion into GTO would be handled by that last stage, making a third burn in total. That is the burn I was referring to as presenting the freezing or pressurization difficulties.
I don't know when somebody got the bright idea of having the final kick motor on the satellite itself, as a sort of final stage, using hypergolics or something else that keeps well. The satellite needed it anyway, for station-keeping. But I strongly suspect that they didn't think right away of starting off with an apogee 50% higher than GEO so that the essential energy level of the orbit starts off more or less the same as the target orbit.
Though I'm not sure exactly what the benefit of that is (Less time in the radiation belts? Easier to raise the perigee?). After all, delta V is delta V. It has to use propellant to increase the perigee, and then some more to decrease the apogee.
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#711
by
rpapo
on 17 Dec, 2013 18:19
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Yes, they did. The sling shot maneuver was proposed in 1961 and used by Mariner 10 in 1973 (which means it was designed in the 60's).
Slingshot after slingshot after slingshot, for years on end? They had many years, many dozens of orbits of the Cassini probe all laid out ahead of time. I remember seeing it on their web site in 2004. How many times to see Titan, how many to see Iapetus, etc, and exactly when. They had all the course corrections laid out already.
Even more fun, they used their slingshots very wisely to change the plane of the orbit, sometimes radically, to do tricks like those pictures of Saturn's poles we've been seeing on the internet lately.
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#712
by
Jim
on 17 Dec, 2013 18:28
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I don't know when somebody got the bright idea of having the final kick motor on the satellite itself, as a sort of final stage, using hypergolics or something else that keeps well. The satellite needed it anyway, for station-keeping. But I strongly suspect that they didn't think right away of starting off with an apogee 50% higher than GEO so that the essential energy level of the orbit starts off more or less the same as the target orbit.
Since day 1 (going back to Syncom 1, the first GSO satellite). All the Delta and Atlas spacecraft going to GSO had the kick motor in them. All commercial comsats have kick motors or boost systems. Only the DOD spacecraft on Titan IIIC, 34D and IV using Transstage, IUS, and Centaur and Delta IV Heavy have relied on the launch vehicle for final injection into GSO, which is the exception vs the rule.
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#713
by
Jim
on 17 Dec, 2013 18:29
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Yes, they did. The sling shot maneuver was proposed in 1961 and used by Mariner 10 in 1973 (which means it was designed in the 60's).
Slingshot after slingshot after slingshot, for years on end?
You wouldn't believe the designs of missions than never made it past the paper stage.
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#714
by
Jim
on 17 Dec, 2013 18:31
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While I will agree that there is no essential difference between the second burn of Falcon and that of the other rockets you referred to, what I was originally referring to was the notion (long ago) that the final insertion into GTO would be handled by that last stage, making a third burn in total. That is the burn I was referring to as presenting the freezing or pressurization difficulties.
Not really any problem. Titan IV Centaur did it every time. Same goes for Delta IV Heavy east coast missions.
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#715
by
rpapo
on 17 Dec, 2013 18:33
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Since day 1 (going back to Syncom 1, the first GSO satellite). All the Delta and Atlas spacecraft going to GSO had the kick motor in them. All commercial comsats have kick motors or boost systems. Only the DOD spacecraft on Titan IIIC, 34D and IV using Transstage, IUS, and Centaur and Delta IV Heavy have relied on the launch vehicle for final injection into GSO, which is the exception vs the rule.
Which begs the question: given that using a kick motor that is part of the satellite is more efficient and practical, why would the DOD use the final stage that way at all? Not arguing here. Just curious and learning stuff...
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#716
by
Chris Bergin
on 17 Dec, 2013 18:36
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Remember to keep on topic on these threads. Nothing uninteresting about the posts, but when you see splinter discussion, start a new thread, link both threads in those threads. Then everyone's happy.
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#717
by
Jim
on 17 Dec, 2013 18:39
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Which begs the question: given that using a kick motor that is part of the satellite is more efficient and practical, why would the DOD use the final stage that way at all? Not arguing here. Just curious and learning stuff...
Legacy. Because they designed the rocket first (Titan IIIC) and then they were to use the IUS and Centaur on the shuttle.
Sorry about the splinter. I will leave it to rpapo if he wants to continue.
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#718
by
Galactic Penguin SST
on 15 Feb, 2015 12:05
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So I recently bumped into references to CASSIOPE again lately in this area of NSF and I suddenly remembered - what the heck happened to that hexagon box that no-one cared which launched as the primary passenger on the 1st F9-v1.1? I looked around and unfortunately can't find much (there's nothing new on CSA's website, or at least from what I could find).
However the
ionosphere research experiment package has been working nicely since late 2013 till now, although I can't find any related scientific findings from it. You can see some of the images from it at
https://eoportal.org/web/eoportal/satellite-missions/c-missions/cassiope.
The Ka-band store-dump communication package experiment has also been working, and
in a technical presentation last August MDA reported that it was used operationally to increase the data transfer rate of the ionosphere research experiment from 4 Mbps to 340 Mbps! They concluded that a larger version of it can be able to support 2.4 Gbps data transfer rate.
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#719
by
eeergo
on 22 Feb, 2018 15:49
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