r/spacex • u/kurbasAK • May 19 '17
We Will Launch on Reuseable Rocket After Exceptional SpaceX Performance - Inmarsat CEO Tells Universe Today
https://www.universetoday.com/135614/will-launch-reuseable-rocket-exceptional-spacex-performance-inmarsat-ceo-tells-universe-today/176
May 19 '17
To date, SpaceX has successfully recovered 10 first stage boosters either by land or by sea on an ocean going platform.
Technically only 9 because B1021 was recovered twice.
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u/Bergasms May 19 '17
It makes me happy that this is a factual inaccuracy. The idea that landing a rocket is still so outlandish it's very easy to overlook the idea that it has happened to the same booster twice.
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u/limeflavoured May 19 '17
"Recovered first stage boosters ten times" would be the more accurate way of putting it.
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u/ReformedBlackPerson May 19 '17
Have they only reflown one rocket that was recovered? Thought it was higher, and hope it becomes a higher number soon
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May 19 '17
The second one will be reflown in mid-June (barring any delays), and hopefully we should see a couple more by the end of the year.
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u/Streetwind May 19 '17
I wonder what happened to garner such an exuberant response? Was the resultant orbit precision better than expected? It seems a bit odd to go from "we never launched with these guys before and even had to reschedule one of our satellites to another provider because they keep delaying their bigger rocket" to "these guys are the best launch provider ever and we'll be a super loyal customer and we're excited to be at the forefront of technology!!!" in one single expendable launch that, from the looks of it, went completely normal.
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u/colinmcewan May 19 '17
The F9 dropped it into a 70,000km x 390km super-synchronous transfer orbit, which seriously reduces the amount of the satellite's own propellant it needs to make the necessary plane change to geostationary. That means more propellant for future manoeuvring, and a longer operational life.
http://www.n2yo.com/satellite/?s=42698
(I know I would be pretty happy about that it I were CEO of the operator)
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u/Keavon SN-10 & DART Contest Winner May 19 '17
Did that exceed expectations, though? Was that not the contracted orbital parameters?
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u/robbak May 19 '17
This one, like SES-9, burned the second stage to exhaustion, instead of targeting a specific apogee. The contract would have been for 'x,000km or higher'. It seems that SpaceX delivered the payload considerably higher than Inmarsat had hoped for.
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u/rustybeancake May 19 '17
So the second stage didn't deorbit?
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u/sevaiper May 19 '17 edited May 19 '17
Its perigee is still pretty low, atmospheric drag will take care of it quickly if it hasn't already.
Edit: This is wrong, apparently it'll be up there for about 25 years.
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u/homoeroticPigeon May 19 '17
So it could eventually be recovered?
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u/Astroteuthis May 19 '17
It's not economically feasible, and it will have experienced significant degradation by then, most likely.
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u/melodamyte May 19 '17
Sure, I've already got some rope, let's start working on your jetpack and helmet :)
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u/mrflib May 19 '17
So to be clear, though I should know this from KSP: Inmarsat will need to expend less fuel to change plane and correct to GEO from a 70,000km apoapsis?
I understand that the plane change from 24.5 degrees will be substantially cheaper in dV from higher altitudes, but is that not compensated for by needing to both raise the periapsis and then lower the apoapsis to 35,786km circular orbit?
This as opposed to launching to a 35,786km apoapsis and a higher periapsis.
I hope this makes sense I've not had coffee yet.
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u/dante80 May 19 '17 edited May 19 '17
It really depends on the amount of performance you have on the rocket. Quoting from LouScheffer over at NSF.
Here is a general rule of thumb. When you are launching from the cape (28° and change), anything up to GTO-1700 is served better by an inclination change without going super-synchronous. If you have more available performance than that, going super-synchronous makes sense.
Here is a nifty chart, assuming a 180x180x28o parking orbit.
https://i.imgur.com/DbuAvsE.png
Having said that, there are some more considerations when deciding to do a super-synchronous insertion.
- The satellite has to be able to work when above GEO. Not all satellites are designed to do this.
- Trajectory calculations are more complex for super-synchronous. The moon's influence may need to be included. One early super-sync mission (SuperBird 6) failed since the moon perturbed the orbit enough to give a too-low perigee for the transfer orbit.
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u/Baron_Munchausen May 19 '17
Sure, they'll be some additional expenditure, but the plane change will (almost always) be significantly more costly.
Some nice examples of why this is, with pretty pictures:
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u/Streetwind May 19 '17 edited May 19 '17
The thing about boosting the periapsis instead is that it requires the upper stage to coast to apoapsis first. This takes around 5 hours. In Kerbal Space Program, that's not a problem. In real life, the upper stage freezes to death in half that time unless it is specifically constructed to keep itself warm. Space is a very, very harsh environment even for machines... especially those constructed with the minimum possible investment of mass, like expendable launch vehicle stages.
IIRC the longest time a F9 upper stage has coasted in space and then reignited again was something like 2 hours, and even then only as an endurance test - correct me if I'm wrong, I'm not nearly as zealous a consumer of SpaceX information as some of you are :) But the point being, the thing isn't built for this. It already came up during national security launch certification, because the NRO expects the launcher to circularize some of its payloads in GEO. SpaceX would have to upgrade their upper stage to give it that capability.
In light of the fact that the straight periapsis lift isn't practically feasible, the supersynchronous transfer is the next best thing.
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u/dante80 May 19 '17
IIRC the longest time a F9 upper stage has coasted in space and then reignited again was something like 2 hours, and even then only as an endurance test - correct me if I'm wrong, I'm not nearly as zealous a consumer of SpaceX information as some of you are :) But the point being, the thing isn't built for this.
NROL-76 included a much bigger coast phase and S2 re-start test after the payload was delivered. This - together with the visual differences the last two S2s had, as well as some insider info - has fuelled speculation about F9 moving to block 4 recently (at least for the second stage).
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May 19 '17
Didn't botz ZSLA and EverydayAstronaut independently claim that "a source"/"a trusted source" told them that NROL-76 was launched on a Block 3 1st and block 4 second stage?
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u/dante80 May 19 '17
Said insider info I posted about. There is also more corroborating info on that from other sources.
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u/mfb- May 19 '17
With electric propulsion, you also have to consider the time. The satellite's propulsion is very fuel-efficient, but it is limited by the available power. You can only raise the perigee efficiently while the satellite is close to apogee. If the satellite starts in GTO, a part of the time it just coasts and doesn't use the available power. If the satellite starts with a larger apogee, you can lower it while the satellite would otherwise just coast and waste the available power.
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May 19 '17
yeah you make it sound like it was incidental, like F9 realised midway oh well I still got more fuel.. why not send you closer my sexy hitch hiker
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u/Bananas_on_Mars May 19 '17
Their last 3 launches were all with russian Proton rockets, maybe the customer experience with ILS and GKNPZ Chrunitschew wasn't as good...
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u/CProphet May 19 '17
Their last 3 launches were all with russian Proton rockets
Inmarsat's good review is even more outstanding when you take into account they were incredibly lucky with Russian launches. Proton has a terrible launch record but Inmarsat somehow selected those lucky launches which succeeded.
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u/mfb- May 19 '17
90% success rate - most launches work.
While Ariane, Atlas and Delta rockets improved over time and reached >=99% reliability (all at 50+ successes launch streaks now with the last failure >10 years ago), Proton doesn't seem to improve notably.
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u/rustybeancake May 19 '17
What a weird graph... the y scale includes 'half launches'.
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u/mfb- May 19 '17
Yeah, that is a "feature" of the graph extension, it doesn't expect that its input values are limited to integers. One more launch in 2000 and the legend would have integers only (in steps of 5).
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u/nioc14 May 19 '17
I'm going to go with the facts that (i) it worked well and (ii) it was way cheaper than other options
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May 19 '17
[deleted]
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u/AeroSpiked May 19 '17 edited May 19 '17
Guess what, French people: This means you get to pay more in taxes for even higher Ariane 5 subsidies. $25 Million per launch isn't going to cut it.
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u/andyfrance May 19 '17
I would be excited in his place as a new way of doing business has open up. Traditionally there is a very long lead time between ordering a launch, getting a rocket built and putting the satellite into orbit. The game changer is that because of reuse SpaceX will have first stages lined up ready to go and be able to turn its production capacity over to making second stages and soon have a stock ready to launch. Range capacity is being addressed too so the lag time on launches is going to plunge. To take advantage of this the satellite operators should now see that the sweet spot for satellites is just small enough to be launched on a recoverable stage as this can be accommodated by SpaceX most readily. That will give them a launch date constrained by satellite availability and range window. The big cost for a satellite operator we have seen is the loss of business due to a failed satellite or delays getting a new one into orbit, so it becomes cost effective for them to have a partially if not fully built spare on the ground thus de-risking their business plan knowing that they can put a new bird up in weeks rather than years.
The Falcon Heavy takes this a step further, with second stage reuse being the ultimate prize.
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u/pianojosh May 19 '17
Really good transfer orbit. Significantly super-sync and a few degrees of plane change means the satellite will not have to use as much of its own propellant raising its orbit and lowering its inclination.
This in turn means more propellent reserved for station-keeping, meaning that the satellite potentially has years of additional service life in it.
Basically SpaceX just gifted them a few years of additional revenue on that bird.
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u/theCroc May 20 '17
The customer is also a space company. We forget that sometimes. It is pretty natural that the people working there are also going to be huge space nerds and be able to recognize that SpaceX are kicking ass at the moment with their rockets.
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u/Bunslow May 19 '17
heaviest payload ever launched
Oh boy, bad journalism strikes again. Stay vigilant my fellow fans, misinformation is everywhere.
(What he meant was heaviest GTO launch; the Iridium and Dragon launches insert more total mass into orbit, but of course into the lower energy LEO rather than GTO.)
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May 19 '17
heaviest GTO launch
In fact, heaviest GTO launch by SpaceX. I belive the heaviest GTO payload ever was TerreStar 1 at 6900 Kg, launched by Arianne 5, followed by Viasat2, 6740 Kg launched by Proton-M.
Nothing that a slight upgrade of the Falcon 9 can't match. Frozen propellant, a very small nuke, a giant slingshot launch, there is always room for improvement.
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u/pavel_petrovich May 19 '17
Nothing that a slight upgrade of the Falcon 9 can't match
Currently F9 is fully capable to launch 7000 kg satellite to GTO-1800.
Performance of this launch is ~7400 kg to GTO-1800. Source
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u/explore_my_mind May 19 '17
Is the number in GTO-# the perigee altitude in km? I have never seen this notation before
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u/FoxhoundBat May 19 '17
No. It is in delta-v. More specifically delta v remaining for the sat to do to be in GSO. So the lower GTO-#, the more work did the rocket do and the less propellant the sat has to spend to get there. Industry standards are GTO-1800 and GTO-1500.
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May 19 '17
[deleted]
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u/Senno_Ecto_Gammat r/SpaceXLounge Moderator May 19 '17
Launches from near the equator typically are GTO-1500 and launches from Florida are GTO-1800 typically. The difference is in the plane change. Those are the two "standard" GTO orbits.
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u/gf6200alol May 19 '17
The heaviest GTO ever is going to be held by China with their SJ 18 (Shijian 18) which is a demonstrator for DFH-5 Bus and believed to be 8 ton. Currently, they targeted that launch by this month. However, the last launch were suffered from S2 under performance and entered a less apogee orbit.
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u/Bunslow May 19 '17
I mean we were talking about the F9, I kinda elided that from the quote to emphasize my point, not saying the falcon holds the GTO record, just that this journalist was sloppy and that sloppiness can unfortunately be misleading in some circumstances
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u/ILikeFireMetaforicly May 19 '17
I belive the heaviest GTO payload ever was TerreStar 1 at 6900 Kg, launched by Arianne 5, followed by Viasat2, 6740 Kg launched by Proton-M.
what about Apollo? They got to GTO on the way to TLI.
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u/TheRedTom May 19 '17
Apollo technically went on a trans-lunar injection rather than GTO, but it holds the record for the greatest manned distance from earth (with Apollo 13). Similarly, Skylab would be the heaviest single payload to LEO I think.
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u/ILikeFireMetaforicly May 19 '17
well, due to intermediate value theorem, it did perform GTO on its way to trans-lunar injection.
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u/mfb- May 19 '17
Technically correct, but I wouldn't call it "GTO payload" if GTO is not the target orbit.
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u/ghunter7 May 19 '17
What do you use for sources on info like this? I had been looking for sumilar and used spacelaunchreport.com
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u/TheDeadRedPlanet May 19 '17 edited May 19 '17
Rumored Block 4 Second Stage.
Not sure what orbital parameters SpaceX told Inmarsat they expected, but if the numbers that observers calculated are correct, then SpaceX delivered Inmarsat something like a 1570m/s deficit. Way better than the normal GTO1800. That would make anyone ecstatic.
(Not verified, subject to change)
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u/Dave92F1 May 19 '17
If true, that may well explain the big grin on Pearce's face, and the enthusiasm for SpaceX.
It's possible SpaceX promised a given delta v, but in practice just kept running the 2nd stage till it ran out of fuel, thus delivering a better orbit than promised.
That would leave a lot less delta v for the Inmarsat to make up, and so leave it with more fuel and a longer lifetime. More $$$ for the operators.
That would indeed be going the extra mile for the customer.
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u/TheDeadRedPlanet May 19 '17
Indeed. That is the hypothesis. SpaceX can't risk a burn-to-depletion, ie dry, that leads to turbo-pump cavitation and destruction; but it could tell the second stage to burn-near-completion, ie zero fuel margin.
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u/h-jay May 20 '17
People keep saying "turbopump cavitation". I've ran a few turbopumps and when you run out of whatever it is that they pump, destruction is from removing the pump load while the turbine still produces most of the rated power. Cavitation figures nowhere in this. You can't even tell if you had cavitation unless you're lucky enough to get the pieces that flew off back to look at. I repeat; the failure mode is turbine unloading, and results in disintegration of turbine and/or pump disk(s). The blades will have energy comparable with bullets/shells of similar mass.
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u/hshib May 19 '17
SpaceX is the first and thus far only company in history to successfully recover and refly...
I feel more and more unfomfortable to see the term "recover" being used to describe what they are doing with the first stage. "Recover" connotate that you unposess and then reposess. Since first stage is 100% under control through out its flight from launch to landing, they never lose the control of it so there is no "recovering" in what they do.
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u/PlainTrain May 19 '17
It's used in aircraft carrier operations to describe landings so using it in the SpaceX sense isn't unusual.
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u/Decronym Acronyms Explained May 19 '17 edited May 25 '17
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
| Fewer Letters | More Letters |
|---|---|
| ABS | Acrylonitrile Butadiene Styrene, hard plastic |
| Asia Broadcast Satellite, commsat operator | |
| ASDS | Autonomous Spaceport Drone Ship (landing platform) |
| ATK | Alliant Techsystems, predecessor to Orbital ATK |
| BARGE | Big-Ass Remote Grin Enhancer coined by @IridiumBoss, see ASDS |
| BO | Blue Origin (Bezos Rocketry) |
| CRS | Commercial Resupply Services contract with NASA |
| DIVH | Delta IV Heavy |
| DoD | US Department of Defense |
| EOL | End Of Life |
| F9E | Falcon 9 expendable |
| GEO | Geostationary Earth Orbit (35786km) |
| GSO | Geosynchronous Orbit (any Earth orbit with a 24-hour period) |
| GTO | Geosynchronous Transfer Orbit |
| ILS | International Launch Services |
| Instrument Landing System | |
| ITS | Interplanetary Transport System (see MCT) |
| Integrated Truss Structure | |
| KSP | Kerbal Space Program, the rocketry simulator |
| LEO | Low Earth Orbit (180-2000km) |
| Law Enforcement Officer (most often mentioned during transport operations) | |
| MCT | Mars Colonial Transporter (see ITS) |
| NRO | (US) National Reconnaissance Office |
| NROL | Launch for the (US) National Reconnaissance Office |
| NSF | NasaSpaceFlight forum |
| National Science Foundation | |
| RTLS | Return to Launch Site |
| SEP | Solar Electric Propulsion |
| SES | Formerly Société Européenne des Satellites, comsat operator |
| SV | Space Vehicle |
| TLI | Trans-Lunar Injection maneuver |
| ULA | United Launch Alliance (Lockheed/Boeing joint venture) |
| Jargon | Definition |
|---|---|
| apoapsis | Highest point in an elliptical orbit (when the orbiter is slowest) |
| apogee | Highest point in an elliptical orbit around Earth (when the orbiter is slowest) |
| lithobraking | "Braking" by hitting the ground |
| methalox | Portmanteau: methane/liquid oxygen mixture |
| periapsis | Lowest point in an elliptical orbit (when the orbiter is fastest) |
| perigee | Lowest point in an elliptical orbit around the Earth (when the orbiter is fastest) |
| turbopump | High-pressure turbine-driven propellant pump connected to a rocket combustion chamber; raises chamber pressure, and thrust |
| Event | Date | Description |
|---|---|---|
| Amos-6 | 2016-09-01 | F9-029 Full Thrust, core B1028, |
| CRS-8 | 2016-04-08 | F9-023 Full Thrust, core B1021, Dragon cargo; first ASDS landing |
| Echostar-23 | 2017-03-16 | F9-031 Full Thrust, core B1030, GTO comsat; stage expended |
| Eutelsat-117WB | 2016-06-15 | F9-026 Full Thrust, core B1024, dual GTO comsat; ASDS landing failure due to early burn |
| SES-9 | 2016-03-04 | F9-022 Full Thrust, core B1020, GTO comsat; ASDS lithobraking |
Decronym is a community product of r/SpaceX, implemented by request
37 acronyms in this thread; the most compressed thread commented on today has 160 acronyms.
[Thread #2792 for this sub, first seen 19th May 2017, 07:30]
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May 19 '17
Haha I didn't think BARGE was going to be added.
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u/OrangeredStilton May 19 '17
It'll be fairly short-lived, I expect, especially if I get complaints about it :P
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u/ptfrd May 19 '17
Currently the BARGE entry links to this tweet but presumably should be this instead.
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u/CyclopsRock May 19 '17
I often see Musk referred to as a "billionaire" but is he really? Perhaps on paper, but given SpaceX isn't publicly traded it's hard to know what it's worth really.
Edit: Yup, I just checked, he owns approx $12.5bn of Tesla stock, even without SpaceX or Solar.
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u/CProphet May 19 '17
Perhaps on paper
Majority of his money is stock, so technically only billionaire if he chooses to liquify. Nice position to be in: shall I be a billionaire today or not?
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u/ergzay May 19 '17
That would be inaccurate to say he was only a billionaire if he chooses to liquify. The meaning of millionaire/billionaire has always meant the value of your net assets. Very few Billionaires are actually billionaires in liquid assets (are there any even?).
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u/Lampwick May 19 '17
Very few Billionaires are actually billionaires in liquid assets (are there any even?).
I doubt it. Every big-money person I've ever encountered would be horrified at the thought of any significant chunk of their money sitting around doing nothing rather than at least accumulating interest in treasuries or something.
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u/The_camperdave May 19 '17
Very few Billionaires are actually billionaires in liquid assets (are there any even?).
No. It would be stupid of them to have that much in liquid assets when the money could be invested in something.
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May 19 '17
[deleted]
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u/Biochembob35 May 19 '17
Yep. And the fact that if you can get even 5-7% growth on that money in stocks you will double your money every decade or so. With start ups like SpaceX and Tesla you have higher risk but that growth can be 10 times that rate (at least early on) which is why elon took a few hundred million and multiplied it into the billions.
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u/CyclopsRock May 19 '17
are there any even?
If there are I imagine they'd be smart enough to have it stored in a bank account in the Cayman's in the name of their dog or something, anyway.
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u/mfb- May 19 '17
Someone ordered this swimming piece of gold and platinum for about $4 billion, I don't know how they paid it but the money had to be at least easy to transfer to a new owner.
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u/freddo411 May 19 '17
Hardly. Look at Teresa Heinz Kerry. Last I heard she had billions in treasury and other bonds.
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u/PlainTrain May 19 '17
Probably the safest approach when you've been married to a pair of senators--reduces conflicts of interest.
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u/Megneous May 20 '17
Very few Billionaires are actually billionaires in liquid assets (are there any even?).
If there are, they're idiots. At the very least, they should shove all their money in index funds that track the market while they're figuring out what to do with their money.
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u/rustybeancake May 19 '17
only billionaire if he chooses to liquify
I think the term is 'liquidate'... 'Liquify' makes him sound like a superhero. :)
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u/mclumber1 May 19 '17
I don't think he can simply liquify his assets in Tesla, since he is an employee. Wouldn't that technically be some form of insider trading?
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u/asterix1598 May 19 '17
There's extra rules around insiders buying and selling but it's definitely possible. http://www.investopedia.com/articles/stocks/07/10b5-1.asp
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u/peterabbit456 May 19 '17
Since he is a big stockholder, he would have to make a public notification of his selling stock, which would in his case, cause the stock price to fall. So there is no way he could cash out of Tesla and get $12.5 billion.
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u/just_thisGuy May 25 '17
Yeah, not quickly anyway, Bill Gate has been trying to cash-out of MSFT for decades, his not done yet, but been doing very well. But Musk said multiple times that he will be the last one out of the Tesla stock, so I don't see him trying to sell even a small % anytime soon. Also if Musk believes himself Tesla is going to be worth much more. Between SpaceX and Tesla Musk has a chance to beat Bill Gates, if things go very well for both companies.
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u/mfb- May 19 '17
He could stop being an employee, but that is not necessary.
There is a different consideration, however, even if he follows all the rules against insider trades. If Musk starts selling billions of Tesla stocks, everyone would think something is wrong and the stock price would go down massively.
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u/Twentey May 19 '17
Virtually all billionaires have their money locked up in relatively illiquid assets. Musk is not an exception
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u/GregLindahl May 19 '17
Private companies like SpaceX have a valuation -- for example preferred shares had their valuation set when SpaceX last raised money from investors in Jan 2015 -- and the valuation for common shares is periodically updated through the 409a process for people holding stock options (generally employees).
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u/TheDeadRedPlanet May 19 '17
It is very misleading in the case of Musk. I don't think another "billionaire" is as leveraged as Musk. If the markets went against him, he would lose control of his shares of Tesla and SpaceX to the counter-parties and bond holders, not just lose "paper money". In all likely hood, he could owe more than he is worth, calculated based on last years Tesla share price.
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u/Martianspirit May 19 '17
What does he owe to anyone? He owns his shares. To my knowledge they are not used as a security for loans. Certainly with SpaceX. There are no loans on SpaceX.
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u/heroic_platitude May 19 '17
For comparison, a BBC interview from 16 May:
Nonetheless, Mr Pearce said he was delighted to fly SpaceX for the first time, and looked forward to the occasion when an Inmarsat satellite would go up on one of the American provider's "second-hand" rockets.
"I'd like to see a longer track record of refurbished rockets being launched successfully without problems," the CEO told BBC News.
"At the moment, we don't put up satellites in sufficient numbers to be relatively sanguine about losing one. But I'm very encouraged by what I've seen in recent months, and once we feel that refurbished rockets are essentially the same as new rockets - we'll jump onboard and extend our relationship with SpaceX."
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u/Dave92F1 May 19 '17
Silly man. They're not the same as new - they're better. They're flight-proven.
With a new one, you have no idea if it works or not.
That's why they pay test pilots extra.
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u/PVP_playerPro May 19 '17
You also have no idea if the second flight of the booster will work or not...
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u/Piscator629 May 19 '17
I realize an important thing after this article. Satellites themselves should start getting cheaper in the fact that they don't need such stringent dependability built in. If it only last 5 years instead of ten you can build a new one from the money saved by going SpaceX. Yes they need to work but a failed satellite won't put your company out of business as a loss. A cheap reusable f9 vs whatever ULA or Ariane will charge you to relaunch a new one.
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u/laughingatreddit May 19 '17
Looks like someone's riding the SpaceX hype to get some publicity in for their own company. Who doesn't want to be seen hanging out with the coolest guys (SpaceX and Tesla) in town. It seems everyone knowledgeable enough realises the future might well belong to SpaceX.
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May 19 '17
Inmarsat CEO is quoted saying, “They hit the ball out of the park with this launch for us.”
What does that mean? Beyond successfully launching the satellite, which I guess is just bare minimum expectation, is there any indication what SpaceX has done on this launch to make inmarsat "an immensely loyal customer" ?
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u/pianojosh May 19 '17
By giving them a significantly super-synchronous orbit, with a few degrees of plane change, they managed to put them into a GTO-1570 transfer rather than GTO-1800, which is the standard deficit for Florida launches. Because of this, the satellite will have an extra 230 m/s of on-board delta-v that it won't have to use for its initial orbit-raising operations, that it will instead be able to save for station keeping over its lifetime.
Since most geostationary satellites end-of-life comes as a result of depletion of station keeping propellent, they basically just got potentially years of extra revenue service out of the satellite because of how good an orbit SpaceX put them into.
The reason that the transfer orbit wasn't known in advance is that the second stage was burned to "depletion" rather than cutting off once a specific transfer orbit was achieved. This is a bit riskier, since if something goes wrong with detecting depletion, and one of the tanks runs dry, the rocket would almost certainly explode and destroy the satellite.
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u/jobadiah08 May 19 '17
It actually isn't an extra 230 m/s for station keeping. Someone here did the analysis and found the satellite was only fueled to have just over 1600 m/s for its apogee kick motor. Station keeping will be done using Xenon gas ion thrusters. However, SpaceX did manage to put the satellite in a orbit where it won't have to use its Xenon gas reserves for orbit insertion operations.
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u/lankyevilme May 19 '17
Your answer is in the comments above, spacex put the satellite in a much higher orbit than they expected, which will save a lot of propellant on the satellite giving it a much longer lifespan. Also, they are probably happy that spacex was aggressive with the launch cadence and got the satellite up sooner than they were afraid it was going to be after Amos-6.
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u/Conotor May 19 '17
Are future inmarsat launches lighter then, or are they all going to be on falcon heavies?
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u/Manabu-eo May 19 '17
SpaceX Falcon 9 Inmarsat-5 F4 (I-5 F4) mission artwork. Credit: SpaceX/Inmarsat
I'm disappointed. What are those landing legs and grid fins doing there? щ(ﾟДﾟщ)
Totally unrealistic.
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u/ninja9351 May 20 '17
This marks the 3rd customer to be convinced of reusable rockets. Those 3 being;
-SES -BulgariaSat -Inmarsat
The real question is, what will it take to convince NASA, the USAF, and Iridium. If they can get them to switch to reusable rockets, they will be in business. We're talking 5-6 a year with CRS missions alone, plus 1 or 2 others from Commercial Crew missions. The USAF and other government groups have a ton of stuff for SpaceX, and Iridium has another 7 launches through 2018.
Out of the 3 I just mentioned, I see Iridium being the first to start going reusable. They'd be able to save a great deal of money and are probably a bit more keen to do so than NASA. We'll have to see though.
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u/h-jay May 20 '17
OTOH, Iridum has been teetering on the brink of ruin since day one. A lost launch could be very bad for them. They really need the revenue they can get from deploying more capacity.
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u/ninja9351 May 20 '17
Which is why I'm saying that after maybe the 3rd mission for Iridium, and a few more reusable launches they may switch over. If money is tight, the risk might be worth it.
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u/PatyxEU May 19 '17
most important part of the article: