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Space Science Coverage / Re: ESA - Voyage 2050
« Last post by ccdengr on Today at 04:14 pm »
Perhaps an analogy is research at the South Pole - no one cares what ship brought the equipment, just what the research reveals.
I'm not sure that's a great example, considering that the vast majority (all?) of NSF flights to the South Pole are done with US military aircraft.  "More and Better Science in Antarctica through Increased Logistical Effectiveness" https://www.nsf.gov/geo/opp/usap_special_review/usap_brp/rpt/antarctica_07232012.pdf
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What kind of ISP would you have if you used pressure fed from the 6 bar propellant tanks? In other words no turbo pumps. The chamber pressure would be limited to less than 6 bar!
Depends mostly on the nozzle expansion ratio, but it will roughly 300 seconds ISP in vacuum.
It also depends on whether the propellants are gas or liquid. We were discussing the Gravitics GM100 gaseous thruster. However, I wonder if it would be easier to maintain stable ullage pressure by using that 6-bar to push a smaller volume liquid propellants into the engine. You'd have to subtract the heat of evaporation from the heat of combustion of course but you lose that heat of evaporation anyway through the sometimes random boil off process. 

There its a reason why I designed a gas-gas thruster for Gravitics (and other projects).  Simplicity.  Gas is readily available at the thruster inlet with no consideration for microgravity effects, settling, line freezing, etc.  And it is easy to test, with no toxicity and no handling issues for the propellant.
If you're free to discuss it, what feed pressure is the GM100 expecting and is it throttleable?


Looks like it might work for an SS kick stage so a big bundle of small sats (small sat = 10-20t LoL) can make their way to an independent orbit.



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The recent catastrophic accident in Baltimore puts a new light on the risks of collision between ship and station.
You would think that such an accident would be impossible, with too many failures required, but reality bites.

One solution that might have prevented Baltimore is massive rockfill buttresses around the pilings.  Is there a space equivalent?  Nothing to anchor to, of course.

The separate docking station with space buses and taxis looks good in this context.

This accident is just the latest in a long history of such accidents. For instance, from 1960 to 2015 there were 35 major bridge collapses worldwide due to ship or barge collision.

Anytime you have two large masses maneuvering near each other, there is a non-zero chance of something going wrong. We have to take that into account when designing new modes of living in space.

Which is why I have advocated that having a zero-G transfer hub near a rotating space station makes a lot of sense, because:

A. Large spaceships won't have to be built for mating to a rotating space station, reducing cost and complexity for both the spaceships and the stations.

B. Standardized short distance transfer vehicles can be used to transfer cargo and people between the two stations, which will allow such vehicles to be far smaller than long distance vehicles, reducing the mass of potential collisions with the rotating space station.

C. Zero-G stations can be the overflow storage for the rotating space stations, reducing the amount of long term storage, and increasing the carrying capacity of rotating space stations.
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Space Science Coverage / Re: ESA - Voyage 2050
« Last post by LouScheffer on Today at 03:53 pm »
The report:

https://cosmos.esa.int/documents/1866264/1866292/ESA_L4_Expert_Committee_report_Voyage_2050_Moons_of_the_Giant_Planets.pdf
These quotes still seem counterproductive to me:  "the L4 mission concepts considered in this study, with launch in the early 2040s" and "During the CDF studies, the scenario considered was a single A64 launcher. Only after the conclusion of the CDF studies was a double launch scenario introduced for the Enceladus mission, (see paragraph below)."

I realize this is a national prestige matter, but I'd think the prestige attaches to the science, not the launcher.   And talking *18 years* in advance, surely some advance in launcher technology can be assumed.    And at some point, launch will become a commodity.   Perhaps an analogy is research at the South Pole - no one cares what ship brought the equipment, just what the research reveals.
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Primary launch time = 2024-03-29 02:30:00 UTC per CelesTrak.

https://twitter.com/TSKelso/status/1773383899898576944

Quote from: T.S. Kelso
CelesTrak has pre-launch SupGP data for the @Starlink Group 7-18 launch from Vandenberg SFB on 2024-03-29 at 02:30:00 UTC: https://celestrak.org/NORAD/elements/supplemental/table.php?FILE=starlink-g7-18. Deployment of 22 satellites at 03:32:22.460 UTC. Data for 10 backup launch opportunities also provided: https://celestrak.org/NORAD/elements/supplemental/.

https://celestrak.org/NORAD/elements/supplemental/

Launch: 2024-03-29 02:30:00 UTC. Deploy: 2024-03-29 03:32:22.460 UTC.
Launch: 2024-03-29 03:10:00 UTC. Deploy: 2024-03-29 04:12:22.460 UTC.
Launch: 2024-03-29 03:32:00 UTC. Deploy: 2024-03-29 04:34:22.460 UTC.
Launch: 2024-03-29 03:40:00 UTC. Deploy: 2024-03-29 04:42:22.460 UTC.
Launch: 2024-03-29 03:54:00 UTC. Deploy: 2024-03-29 04:56:22.460 UTC.
Launch: 2024-03-29 04:40:00 UTC. Deploy: 2024-03-29 05:42:22.460 UTC.
Launch: 2024-03-29 05:10:00 UTC. Deploy: 2024-03-29 06:12:22.460 UTC.
Launch: 2024-03-29 05:20:00 UTC. Deploy: 2024-03-29 06:22:22.460 UTC.
Launch: 2024-03-29 05:34:00 UTC. Deploy: 2024-03-29 06:36:22.460 UTC.
Launch: 2024-03-29 06:16:00 UTC. Deploy: 2024-03-29 07:18:22.460 UTC.
Launch: 2024-03-29 06:24:00 UTC. Deploy: 2024-03-29 07:26:22.460 UTC.
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https://www.ulalaunch.com/missions/next-launch/delta-iv-heavy-nrol-70
Mar 28 12:25 EDT
Quote
Filling of the common booster cores and the DCSS liquid hydrogen is complete. Passing the 50 percent mark on second stage liquid oxygen.

Mar 28 12:40 EDT
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The Delta Cryogenic Second Stage has been loaded with its liquid oxygen supply. With fueling reported complete, we have a 1.6-million-pound Delta IV Heavy rocket that is loaded for launch at 2:45 p.m. EDT (1845 UTC) today.

Mar 28 12:45 EDT
Quote
The countdown is two hours away from the NROL-70 liftoff time at 2:45 p.m. EDT (1845 UTC). We have a green status board for Delta IV Heavy and ground systems, but weather remains RED.

Mar 28 12:47 EDT
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All weather rules are green at this time.
But, will they be at T-0?

Video capture from NSF Space Coast Live

Edited
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L-1 Weather forecast:

30% GO for March 28th
60% GO for March 29th
90% GO for April 1st

Not going for any launch attempts over the weekend in case of scrub it seems.
Giving way to the back-to-back Falcon 9 launches?
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7:30 PM PDT is about 20 mins after sunset so it should not take the launcher and contrail too long to find sunshine.   

Hopefully it goes on its first attempt.
Rough calculation gives sunlight at about 5 miles up. To reach that altitude won't take long at all.
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General Discussion / Re: Flight crew assignments
« Last post by John_Marshall on Today at 03:28 pm »
I wonder who Pettit's backup will be?

Jonny Kim or Anne McClain, perhaps?

Jonny Kim training in Star City (see my post in the Unassigned Astronauts thread from the 17th) would seem to imply that it is him.
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https://www.ulalaunch.com/missions/next-launch/delta-iv-heavy-nrol-70
Mar 28 12:04 EDT
Quote
A current check of the local weather conditions at Cape Canaveral shows that the launch weather rules for cumulus clouds, disturbed weather and flight through precipitation are RED as a cold front moves quickly over the Cape.
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