Recent Posts

Pages: [1] 2 3 ... 10 Next
1
Gwynne Shotwell is an avid SciFi fan, hens her reference to the tv series Firefly. I do not believe she was referring to something specific. Just her highest dream and thereby what she would like to be talking about in 20 years.

This was about setting high goals, not that they had to be attainable.

Yes, I found that rather odd too. But I don't think she knows something we don't. Its much more likely she doesn't know something we do: how hard it is to go to to a different star. Even Alpha Centauri is so far out of reach with current and future technology that becomes available in her lifetime. I don't think her statements on that topic are more than SciFi dreams.

So you think the highly intelligent CEO of a successful rocket and capsule company knows less about this sort of thing than people here? That's quite a grand assumption.. Not only that but her CTO is regarded as a genius by people who work with him, and someone who has a excellent grasp on technology in many disparate areas, and is undoubtedly well versed in any current and proposed forms of propulsion. Do you really think either of them have any misconceptions on how difficult interstellar travel is?

I dont know if she has a misconception. But she says that she expects to talk about propulsion systems that are capable of "leaving the galaxy". She either does not know what she is talking about or she is SciFi dreaming.

Edit: She did that twice. And both times, her statement would almost make sense if she was talking about the solar system. So she probably does not know the difference between the term "galaxy" and the term "solar system". She probably knows what a galaxy is as a mental picture, but she uses the wrong terms to describe what she wants to say. But even then, its SciFi dreaming. More than anything else at least.
2
Why would SpaceX even need to do prop densification for crew dragon flights? Do they really need the extra performance; the vehicle is only going to LEO? Do they need the extra performance to do 1st stage RTLS? Or can Falcon 9 v1.2 and launch pad infrastructure only support densified prop?

I think Dragon V2 crewed flights might require a different ascent profile that might possibly include throttling to limit g forces... more gravity losses(?). Also, a crewed Dragon V2 masses more IIRC.

NASA Standard 3000 says the crew can take 14 G's on ascent.  I don't know why people think the crew can't take this.


Modern fighter pilots with G suits can take about 9g before passing out. 14G is a LOT more than a human can sustainably ensure. 15g for a minute could easily kill you.

The 14G number is for ascent abort scenario's lasting a very short time (mere seconds). I fully agree with you that sustained high G-levels will cause major injuries and possibly death.
3
It could be her confidence in Mars.

ie: In 20 years the panel won't be talking about what we can do on Mars, because we'll already have found multiple sites with water, and have 100 people on Mars with a high rate of growth.
Yes, that's my interpretation as well.

20 years forom now, if we already have people on Mars, then the obvious question will be: What's next?

I dont know if she has a misconception. But she says that she expects to talk about propulsion systems that are capable of "leaving the galaxy". She either does not know what she is talking about or she is SciFi dreaming.

With sufficiently advanced propulsion, you can reach the Andromeda Galaxy in 30 years. 

http://www.daviddarling.info/encyclopedia/O/one-g_spacecraft.html

This assumes constant acceleration at 1g for 15 years, then constant deceleration at 1g for 15 years.  If you want to come back to Earth, that would be another 30 years, or 60 years round-trip.  Of course, that assumes you would want to come back home, since 5,000,000 years would have passed on Earth.
4
Most of this focuses on taking up relatively small modules - such as the BA-330, and stringing them together into a rotating structure.

However, Bigelow modules could be much, much bigger. The reason they're not, is that they need a lot of mass for micrometeorite protection. If this could be added later, what could you do with larger structures?

A 53 ton Falcon Heavy launcher could launch a torus pressure vessel, say 15m major radius and 11m minor radius. (An outer diameter of 52m)

Subsequent missions could launch:
- Shield sections to cover the 7,000m2 surface area. That's about 20 times the surface area of a BA-330, implying the need for about 400 tons. Can this be obtained from an asteroid retrieval mission?
- A rotating internal module, that rotates inside the torus - probably using magnetic bearings to ensure no contact with the pressure vessel. The crew rotation section has a 25m outer radius.
- A counter rotating weight
- Airlock
- Power / service module / gyro stabilisers etc

New research on maximum tolerable spin rates means you could probably take the outer diameter down to 40m or less. But researching spin rates and g-levels is of course part of the reason for the station.
5
Well judging by that recent Tri Alpha article it seems their investors are more minded now to part with the cash due to their recent progress.
6
From Facebook

ISRO - Indian Space Research Organisation
1 hr Edited

GSAT-6 UPDATE :

After the third orbit raising operation of GSAT-6, realised orbit is: perigee height - 35634 km, apogee height - 35681 km, inclination 1.17 degree. Present longitude is 78 deg & satellite is drifting towards station of 83 degree.
7
Advanced Concepts / Re: Realistic, near-term, rotating Space Station
« Last post by Paul451 on Today at 10:52 AM »
it seems like as good a place to start as any.
I'm thinking in this direction because I think the first step for (pragmatic) AG proponents is to go much, much smaller, and an animal model enables this.  Assuming the 1% principle, I'm working on a proposal for a [6m radius, 12rpm rotation = 1xg] construction that would be suitable/tolerable for animals smaller than 10cm end to end (i.e. spiders/lizards/mice).

1g is a terrible "first step", IMO. The data we don't have is between 0 and 1g. We can do above-1g centrifuges on Earth, and we have some microgravity data from ISS. But in between the two is a void.

The most useful AG first step would be something that gave us at least one data-point between the two. Especially, IMO, a facility that gave us a couple of data-points at the very low end. 1/100th and 1/10th of 1g. Finding out that we can eliminate 90% of the harm done by microgravity with just a tiny trace of centripetal force would re-write the rulebook for long duration missions. (Even if you still had to exercise to avoid muscle-loss.)

And, on the flip-side, finding out that you need at least 90% of 1g to not experience severe effects would also re-write the rulebook for moon/Mars missions and colonisation.

The reason for going so small is that I'm working within the constrains of what could be done within single SpaceX Dragonlab mission: aiming to launch a "biosphere"-type free-flying torus with components that would fit into the trunk section and be assembled telerobotically in space.

If you're trying to keep within the Dragon trunk, then build the biosphere entire within the trunk. No on-orbit assembly required. And, of course, you don't need all the extra systems to make it free-flying. You'll already have power, comms, RCS, GNC, etc, built in.

You spin the entire capsule/trunk, not just the biosphere. 2.5rpm would give you 1/100th of 1g, 8rpm would give 1/10th of 1g. Bam, there's your first two key data-points.

If Elon's idea of a philanthropical mission was to have the "money shot" plants growing in nutrient gel on Mars, I think you could expect a similar effect just from people seeing a torus free flying above Earth: it doesn't actually matter how small the first one is, just so long as we learn from the process of assembling and running it.

Personally I think there's a "money shot" in putting a simple, non-rotating 5-10m diam transparent sphere into LEO seeded with fast growing plants and a couple of cameras on the outside looking in. And I mean very-L LEO, maybe 12 months stability for the first version? 90+% UV-filtering plastic, anti-tear seams, etc, bottle of extra CO₂. A terrarium in space.

High probability that it'll be punctured and deflated long before de-orbiting, and would have almost no scientific value. But it would be a unique and interesting object that wouldn't cost an extraordinary amount.

A properly designed terrarium doesn't need extra CO₂, there'll be enough bacterial activity to recycle carbon, but the low-levels limit plant growth rates. That's a good thing in a conventional terrarium, since it stops the plants outgrowing the container. But for a simple 12 month gimmick, we want fast growth. Extra CO₂ is much easier than trying to balance photo-synthesizers and respirators on the very first attempt.
8
Spaceflight Entertainment and Hobbies / SLS Heavy Model
« Last post by saturnapollo on Today at 10:47 AM »
Here's my interpretation of what the SLS heavy might look like if it ever flies. I used my old scratchbuilt Saturn V launch tower (modified in Photoshop to try and disguise the fact) for illustrative purposes only.

1/144 scale.

http://www.keithmcneill.pwp.blueyonder.co.uk/SLS5m2.jpg
http://www.keithmcneill.pwp.blueyonder.co.uk/SLS6v.jpg
http://www.keithmcneill.pwp.blueyonder.co.uk/SLS3j.jpg
http://www.keithmcneill.pwp.blueyonder.co.uk/SLS2k.jpg
http://www.keithmcneill.pwp.blueyonder.co.uk/SLS4e.jpg
http://www.keithmcneill.pwp.blueyonder.co.uk/SLS1g.jpg

Keith
9
Yes, I found that rather odd too. But I don't think she knows something we don't. Its much more likely she doesn't know something we do: how hard it is to go to to a different star. Even Alpha Centauri is so far out of reach with current and future technology that becomes available in her lifetime. I don't think her statements on that topic are more than SciFi dreams.

So you think the highly intelligent CEO of a successful rocket and capsule company knows less about this sort of thing than people here? That's quite a grand assumption.. Not only that but her CTO is regarded as a genius by people who work with him, and someone who has a excellent grasp on technology in many disparate areas, and is undoubtedly well versed in any current and proposed forms of propulsion. Do you really think either of them have any misconceptions on how difficult interstellar travel is?

I dont know if she has a misconception. But she says that she expects to talk about propulsion systems that are capable of "leaving the galaxy". She either does not know what she is talking about or she is SciFi dreaming.

Edit: She did that twice. And both times, her statement would almost make sense if she was talking about the solar system. So she probably does not know the difference between the term "galaxy" and the term "solar system". She probably knows what a galaxy is as a mental picture, but she uses the wrong terms to describe what she wants to say. But even then, its SciFi dreaming. More than anything else at least.
10
The CRS contract is for tonnage not flights, OA planned on 8 flights OA1-8. With the switch to more powerful LVs ie Atlas and Antares 230 they can now meet that tonnage with less launches.

Yes, but the numbers do not add up.

CRS-D   700 kg
CRS-1 1261 kg
CRS-2 1494 kg
CRS-3 2215 kg
CRS-4 3500 kg
CRS-5 3500 kg
CRS-6 3200 kg
CRS-7 3200 kg
-------------------
Total 19,070 kg which is less than the 20,000 kg ordered.

Arachnitect says they are not planning on making up for CRS-3. This would explain some of the short falls people have calculated.

I don't known the ins and outs of contract but I think Orbital are paid for max rated play load per mission eg CRS2 = 2000Kg so that is $180M. NASA pays for 2000kg regardless of how much they actually load into Cygnus.
This does make sense, if you charter a 40t truck you pay same price whether it you load it with 1kg or 40t.
 
Orbital stand to make a significant profit per mission by switching to RD181, 3200Kg x $90K = $288M, compare this to CRS2 at $180M for 2000Kg.
At $315M (3500kg) for Atlas V missions it is not surprising they decided to buy a second one. 

Pages: [1] 2 3 ... 10 Next