Quote from: Robotbeat on 09/15/2020 01:52 amQuote from: TrevorMonty on 09/14/2020 10:55 pmThe payload of Photon is limited due to it starting at LEO with 300kg when launched on Electron. Use 1000kg LV like Firefly Alpha and it could be 300kg at earth escape. This could be done with combination of kickstage and delivery to higher orbit by LV.Something to consider for any follow on missions.RocketLab has already increased their payload and may have more payload increases planned. Also, an electric ion/plasma propulsion stage would be a good fit for this and should allow even higher performance, although even just a Photon with stretched tanks should allow significant payload to Venus. The Pioneer Venus small probes each weighed only 90kg, and we could probably do less nowadays even with a parachute. With the kick stage operating as the relay satellite, there's a very large savings in both cost and mass.This mission isn't going to use Firefly Alpha.In-space refueling of the Electron second stage and Photon would get you most of the way to 300kg to a Trans Venus Injection trajectory (if the previous analysis we did in an AAS depot paper on refueling a VO LauncherOne class upper stage/kick stage is any indication). I'd love to run the numbers for Electron/Photon, but have so far been too busy.~Jon
Quote from: TrevorMonty on 09/14/2020 10:55 pmThe payload of Photon is limited due to it starting at LEO with 300kg when launched on Electron. Use 1000kg LV like Firefly Alpha and it could be 300kg at earth escape. This could be done with combination of kickstage and delivery to higher orbit by LV.Something to consider for any follow on missions.RocketLab has already increased their payload and may have more payload increases planned. Also, an electric ion/plasma propulsion stage would be a good fit for this and should allow even higher performance, although even just a Photon with stretched tanks should allow significant payload to Venus. The Pioneer Venus small probes each weighed only 90kg, and we could probably do less nowadays even with a parachute. With the kick stage operating as the relay satellite, there's a very large savings in both cost and mass.This mission isn't going to use Firefly Alpha.
The payload of Photon is limited due to it starting at LEO with 300kg when launched on Electron. Use 1000kg LV like Firefly Alpha and it could be 300kg at earth escape. This could be done with combination of kickstage and delivery to higher orbit by LV.Something to consider for any follow on missions.
Quote from: M.E.T. on 09/15/2020 07:25 amQuote from: jongoff on 09/15/2020 05:22 amQuote from: Robotbeat on 09/15/2020 01:52 amQuote from: TrevorMonty on 09/14/2020 10:55 pmThe payload of Photon is limited due to it starting at LEO with 300kg when launched on Electron. Use 1000kg LV like Firefly Alpha and it could be 300kg at earth escape. This could be done with combination of kickstage and delivery to higher orbit by LV.Something to consider for any follow on missions.RocketLab has already increased their payload and may have more payload increases planned. Also, an electric ion/plasma propulsion stage would be a good fit for this and should allow even higher performance, although even just a Photon with stretched tanks should allow significant payload to Venus. The Pioneer Venus small probes each weighed only 90kg, and we could probably do less nowadays even with a parachute. With the kick stage operating as the relay satellite, there's a very large savings in both cost and mass.This mission isn't going to use Firefly Alpha.In-space refueling of the Electron second stage and Photon would get you most of the way to 300kg to a Trans Venus Injection trajectory (if the previous analysis we did in an AAS depot paper on refueling a VO LauncherOne class upper stage/kick stage is any indication). I'd love to run the numbers for Electron/Photon, but have so far been too busy.~JonSorry, how would in space refuelling of an expendable rocket work? Are you proposing multiple expendable tanker launches to top up the spacecraft propellant tank in orbit?I should've been clear that I wasn't suggesting this for their 2023 mission, but as a way to improve capabilities for future missions. I was referring to having the Electron Stage 2/Photon/Payload stack dock with a microsatellite launcher refueling depot, which would be topped up from buying excess propellant from bigger launchers as per this AAS paper (reviewed at https://selenianboondocks.com/2018/09/aas-paper-review-raan-agnostic-3-burn-departure-methodology-for-deep-space-missions-from-leo-depots-part-1-of-2/ and https://selenianboondocks.com/2018/09/aas-paper-review-raan-agnostic-3-burn-departure-methodology-for-deep-space-missions-from-leo-depots-part-2-of-2/). I realize that this probably isn't the thread to get into the merits of that particular concept, I was just mentioning it for context about how they could upgrade their capacity pretty dramatically with only minor changes. If one of the Mods would like to suggest a better thread for being able to discuss this concept further, that would probably be better than distracting further from the discussion about their 2023 Venus mission.~Jon
Quote from: jongoff on 09/15/2020 05:22 amQuote from: Robotbeat on 09/15/2020 01:52 amQuote from: TrevorMonty on 09/14/2020 10:55 pmThe payload of Photon is limited due to it starting at LEO with 300kg when launched on Electron. Use 1000kg LV like Firefly Alpha and it could be 300kg at earth escape. This could be done with combination of kickstage and delivery to higher orbit by LV.Something to consider for any follow on missions.RocketLab has already increased their payload and may have more payload increases planned. Also, an electric ion/plasma propulsion stage would be a good fit for this and should allow even higher performance, although even just a Photon with stretched tanks should allow significant payload to Venus. The Pioneer Venus small probes each weighed only 90kg, and we could probably do less nowadays even with a parachute. With the kick stage operating as the relay satellite, there's a very large savings in both cost and mass.This mission isn't going to use Firefly Alpha.In-space refueling of the Electron second stage and Photon would get you most of the way to 300kg to a Trans Venus Injection trajectory (if the previous analysis we did in an AAS depot paper on refueling a VO LauncherOne class upper stage/kick stage is any indication). I'd love to run the numbers for Electron/Photon, but have so far been too busy.~JonSorry, how would in space refuelling of an expendable rocket work? Are you proposing multiple expendable tanker launches to top up the spacecraft propellant tank in orbit?
I still think large kick stage on likes of Firefly Alpha is better and lot less complex option. Forget about refuelling 2nd stage which isn't really design for job without lot modifications. Only advantage to 2nd stage is slight higher ISP engine but extra dry mass may counter that especially as Rutherford and its battery are lot heavier than Hypercurie.
While I'm fan of fuel depots, sometimes single launch on bigger LV is easier and cheaper. Electron is $7m for 300kg, vs Firefly $15m for 1000kg.
My hobby horse is Photon for delivering cargo to space station. I can see it being used for emergency spares or high value time critical science experiments. Currently ISS holds 13,000kg of spares, if RL could offer delivery within 2 weeks I'm picking NASA could reduce that spares holding considerably. Not only do spares take up valuable space but mass also uses additional station keeping fuel.Spare in orbit may actually be faulty as its been sitting there for years, fresh one delivered from earth would be tested before launch.This type of service is probably to late for ISS but would ideal for new commercial stations eg Axiom.
Electron has a max payload to LEO of 300 kg per their website. That's using the kick stage, but if we want the second stage to actually make it to LEO, there will probably be a payload hit; I knocked 50 kg off the payload for this estimate, which seemed over zealous, but I figure it's better to over under estimate.With a fully fueled Electron second stage and a 250 kg payload, I get 5,400 m/s of delta-V. If you could store the LOX all the way to Venus, that would be enough to get there, capture, and even lower the orbit by quite a lot.Of course, it require you to have 2.15 (metric) tons of propellant on orbit already to fully refuel the second stage.
....Most people don't realize how much worse the $/kg of net payload delivered to ISS is for most of those vehicles -- it's way higher than the $/kg of just launching something to an ISS-like orbit.~Jon
Quote from: JEF_300 on 09/15/2020 08:24 pmElectron has a max payload to LEO of 300 kg per their website. That's using the kick stage, but if we want the second stage to actually make it to LEO, there will probably be a payload hit; I knocked 50 kg off the payload for this estimate, which seemed over zealous, but I figure it's better to over under estimate.With a fully fueled Electron second stage and a 250 kg payload, I get 5,400 m/s of delta-V. If you could store the LOX all the way to Venus, that would be enough to get there, capture, and even lower the orbit by quite a lot.Of course, it require you to have 2.15 (metric) tons of propellant on orbit already to fully refuel the second stage.Best you can hope for is 2nd stage to survive few hours to do earth escape burn. The fuel depot could top up tanks on Photon or supply it with additional drop tanks. ISP might be lower but no issues with boil off.
Cygnus and Dragon are around $50k per Kg. Photon on electron should be 100kg plus say $100k kg. Not terrible for equivalent of courier delivery to ISS.
Have detachable cargo pod that goes through bishop airlock. Reattach pod with cargo for disposable orbit...
And what about straight up using the F9 US "as is" after it deploys Dragon? Photon would just attach and let the stage do the LEO burn. If F9 US has enough performance margin, it would be a really low risk approach.