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Historical Spaceflight / Re: Boeing's 1968 Human Mission to Mars
« Last post by Blackstar on Today at 12:26 pm »
The majority of U.S. citizens were opposed to the Moon landings, let alone a Mars program.  Mars was dead on arrival.  Nixon could not afford to give it a second thought.  Why do you think you can go see all of those unflown Saturn V rockets and Apollo spacecraft today? 

Everybody should ask Santa Claus to get them a copy of John Logsdon's book "After Apollo?" which goes into this subject in detail. A key thing to understand is that when Nixon entered office in early 1969, he was following a president who had spent a huge amount of money on social programs, and a huge amount of money on fighting the war in Vietnam. Nixon was interested in reining in government spending, and so all his decisions were viewed through that lens. His advisors all viewed government programs from that perspective too. They had no interest in further big space programs. In fact, some of them viewed the efforts in space that ran from 1958-1968 as essentially an aberration, thinking that this was an era that was now ending and should end.

To spoil the big reveal in Logsdon's book, what is shocking is how much further some were willing to go with cutting back spaceflight. There was talk about ending human spaceflight completely, and even talk about eliminating NASA as a space agency--either turning it into a general technology agency, or getting rid of it and maybe handing a few space projects over to another government agency. Once you understand all of that, it is rather amazing that we got what we did with the space shuttle; it could have been a lot less.
One of the advantages of large blobby sphere-like habitats that hasn't been mentioned is Deep Shielding.

If your internal density is the typical 100-200 kg/m3, then at the center of a ~40 m radius habitat you'll have an additional 4-8 tonnes/m2 of radiation shielding "for free." This is on top of whatever shielding and/or inventory mass you supply on the outer surface.

Perfect place to put your low-rad lab and your "maternity home"!  ;D (RIP George Carlin)

The Rashid Rover, the first Emirati mission to the surface of the Moon, will launch in just a few days. What will the rover study?

Option 1: rotation axis pointed at the sun throughout the year
Option 2: having the plane of rotation going through the sun (i.e. "edge-on" rotation, axis points North-South).

What's the advantage of option 2 over option 1?

Rotating the axis once-per-year is not a high delta-v cost (at least relative to every other delta-v cost). And I see no other "savings" and lots of added complexity in option 2.

(For eg, you take the non-rotating section branching off the hub as a given for an option 2 station. Yet any non-rotating hub connection makes every rotating-station problem vastly harder. Now you can't tolerate any drift of the centre-of-rotation from the centre-of-structure, which means your mass distribution in three dimensions must be held exactly constant. Icky.)

Bolded the caveat cause I feel like I'm missing something. With Option 2, I'm talking about the use case where every other dV cost goes to zero or close to it.

At this point you're squabbling over scraps. The resupply mass is insignificant compared to other needs.

Say when you have finished building and spinning up a multi-hundred-metre toroid

That's the first mistake of the post. :)

or larger at L4/L5...

Do you have a good reason to be at EML4/EML5? Or is this just a contrived and/or booby-trapped counterexample?

EML4 and EML5 have stationkeeping requirements of 5-7 m/s per year, so we've already blown the "close to zero" requirement.

you've got a huge moment of inertia

One of the problems with a torus, yes.

, and the orbit is stable without propulsive station keeping.


There's no need to speed up or slow down the spin

...unless you ever add or remove mass from the station.

(Yes I know, before you "correct" me, the angular velocity isn't what changes, but the angular momentum changes which is what actually matters here)

[skip a bit, Brother!]

Seems to me that the larger your habitat, the bigger that cost is relative to everything else

Why do you believe that?

The (small) cost scales roughly with the station mass... just like all your other costs.
ISS Section / Re: Expedition 67 Thread
« Last post by Rondaz on Today at 11:29 am »
When I visited last time, three years ago, Venice was experiencing the tail end of a devastating flood. Great to see that the city is now protected!

Completion of the initial operation of the JAXA CubeSat EQUULEUS
November 26, 2022 (JST)
Japan Aerospace Exploration Agency (JAXA)

The Japan Aerospace Exploration Agency (JAXA) is pleased to announce that a series of scheduled function verification operations have been completed for the JAXA CubeSat EQUULEUS, which was launched by NASA's Artemis I on November 16, 2022 JST. As a result of the orbit maneuver control and orbit corrections before and after the lunar fly-by, the lunar fly-by was completed as planned on November 22 JST and EQUULEUS has been confirmed to be in the planned orbit towards the second Earth-Moon Lagrange point (EML2). This is the world’s first successful orbit control beyond low-Earth orbit using a water propellant propulsion system.

From now, EQUULEUS will move from the initial operation phase onto the normal operation phase, and reach the Lagrange point in approximately 1.5 years.

We would like to express our sincere gratitude to everyone for their cooperation and support during the launch and tracking control.

Comment by FUNASE Ryu,
JAXA Institute of Space and Astronautical Science, Professor / Department of Aeronautics and Astronautics, School of Engineering, The University of Tokyo, Associate Professor:

I am proud of the EQUULEUS operation team, who were able to immediately complete the orbital control necessary for the lunar fly-by, just one day after the checkout operation shortly after launch. This was a difficult operation that had to be successful. I feel we were able to succeed in this critical operation due to their careful preparation, including numerous back-up plans, and the ability to respond flexibly through training. We are now at the start line of the long voyage to the Lagrange point. Thank you for your continual support!
Cape Canaveral/Kennedy Space Center, FL temporary restriction:

From November 26, 2022 at 1845 UTC to To November 26, 2022 at 1946 UTC
Altitude: From the surface up to and including 18,000ft

Likely:CRS2 SpX-26 (Dragon) (

They said "hello"! Our recently launched #satellites have established contact and the have sent the first beeps. The @strocast space operations team just confirmed their successful communication, our four 3U cubesats are in good shape.
🛰️We are so proud of them!

#SatIoT #PSLVC54
SpaceX Missions Section / Re: SpaceX Manifest Discussion Thread
« Last post by meekGee on Today at 11:20 am »
Did we just note the 1 launch/week milestone for 2022?

That has been the case since the summer.
SpaceX has actually exceeded launching every six days for the last ten or so missions before this most recent hiatus.

edit: When the red line in the graph in this post exceeds 52 (wks/yr=365/7) the pace of the last ten flights exceeds one per week.  Early enough in the year or long enough and it applies to the whole year. 
When it exceeds 61 (365/6) the pace surpasses a launch every six days.
I know, I meant 52 in, so the yearly total has surpassed the 1/week benchmark even if two hurricanes and an earthquake hit tomorrow...

I'm curious how they'll surpass that next year without another barge.  More RTLS doesn't seem productive for Starlinks.
good example of why American habit of early specialization in .... sucks.

I don't understand what you mean by this, Please explain.
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