Future Mars

[dave2013 1,191]

6 hours ago, martin-w said:

The "self scan" technology is designed for a full trolley though. You get a scanner and scan as you shop. Then its simply a case of scan a bar code at the checkout, paying, and then off you go. 

Haven't encountered the scan as you shop here.  The main issue with self-checkout is that oftentimes the counter space is very small so if you have a lot of stuff there's no room for all of it.  The machines will complain if they don't detect the presence of the scanned items on the counter so you can't scan the stuff and just put it back in the cart.

6 hours ago, martin-w said:

NASA and others are working on thermonuclear propulsion as we speak though, offering much faster travel time to the red planet, nuclear electric propulsion offers even faster travel time, and the VASIMIR propulsion method which is being researched as we speak, offers travel time to Mars of as little as a week. Given the larger payload capacity of planned vehicles, including SpaceX Starship, we can expect a presence on mars sooner than you might think. 2030 isn't out of the question, but I'm betting on a little longer than that.

They've been "working on" thermonuclear propulsion for 50 years and we still don't have it.  I can envision a manned brief visit to Mars by 2035, but not a permanent base until well beyond 2040.  We don't even have a presence on the moon yet.

58 minutes ago, dmwalker said:

Would a window of plus or minus 3 weeks be about right for routine flights

I doubt it.  Most space probes travel at about 35,000-40,000mph.  Given the optimistic velocity of 50,000mph, it would take about 3 months to reach Mars.  Even at twice that speed you're still looking at 6 weeks or so.

Dave

[dmwalker 614]

16 minutes ago, dave2013 said:

I doubt it.  Most space probes travel at about 35,000-40,000mph.  Given the optimistic velocity of 50,000mph, it would take about 3 months to reach Mars.  Even at twice that speed you're still looking at 6 weeks or so.

I should have said "launch window" so, for example, how many days after Mars closest approach would it no longer be close enough for a cost effective flight.

[dmwalker 614]

29 minutes ago, dave2013 said:

The main issue with self-checkout is that oftentimes the counter space is very small so if you have a lot of stuff there's no room for all of it.

Where I do my hunting and gathering, you can't take a shopping cart into the self checkout area because it will bog down the efficient flow through. Also, I prefer to pay with cash and the self checkout stations here don't accept cash.

[martin-w 3,370]

9 hours ago, dave2013 said:

They've been "working on" thermonuclear propulsion for 50 years and we still don't have it

 

Nope, they haven't Dave. NTP was researched back in the late 50's to late 60's but research was wound down along with the Apollo program. With no desire to go to Mars it was deemed unnecessary.

Now though, a number of companies have been contracted to develop a NTP system, in order to cut the travel time to Mars in half.

https://www.nasa.gov/news-release/nasa-darpa-will-test-nuclear-engine-for-future-mars-missions/

https://www.nasa.gov/tdm/space-nuclear-propulsion/#:~:text=Nuclear thermal propulsion could be,as early as the 2030s.

Lockheed Martin, Rolls Royce and others involved too. And of course, we have Pulsar Fusion too. 

https://www.aerosociety.com/news/atomic-rockets-are-back/

 

Edited December 17, 2023 by martin-w

[martin-w 3,370]

9 hours ago, dave2013 said:

 

I doubt it.  Most space probes travel at about 35,000-40,000mph.  Given the optimistic velocity of 50,000mph, it would take about 3 months to reach Mars.  Even at twice that speed you're still looking at 6 weeks or so.

Dave

 

3 months with NTP. Less with nuclear electric. And plasma thrust courtesy of VASIMIR would be between one and three weeks. And yes, there is research currently underway on a VASIMIR engine. 

[martin-w 3,370]

9 hours ago, dave2013 said:

Haven't encountered the scan as you shop here.  The main issue with self-checkout is that oftentimes the counter space is very small so if you have a lot of stuff there's no room for all of it.  The machines will complain if they don't detect the presence of the scanned items on the counter so you can't scan the stuff and just put it back in the

 

Rarely have I seen anyone attempt to check out with a full trolley of food, at a basic, small self checkout in the UK. There are always conventional manned checkouts available for a full trolley load. But as I say, most supermarkets now have the scan as you shop system as an option. It's not compulsory, conventional manned checkouts are available too.

Will be doing our full shop this morning and we usually go for the scan yourself. Pretty easy, you just scan each item yourself as you walk around the store, then bag it. 

It seems Europe and the UK get the tech before the US. I think I'm right in saying that chip and pin, and contact less came here first too. 

[dmwalker 614]

5 hours ago, martin-w said:

And plasma thrust courtesy of VASIMIR would be between one and three weeks. And yes, there is research currently underway on a VASIMIR engine. 

Quote from February 22, 2023:

"The timeline for when we’ll see a VASIMR demonstration in space is all dependent on the funding," Chang-Díaz told IE. "Right now, to get this engine ready to fly, we're going to need something on the scale of $150 million (dollars). To launch it to space we'd need maybe another $50-60 million." If that investment were secured now, "we could see this engine flying three years from now". 

The Ad Astra website talks about a 200 kw powered engine but, to make a trip to Mars in three weeks, or even the often quoted 39 days, how much power would be needed? Would that be in the realm of fusion power?

[martin-w 3,370]

45 minutes ago, dmwalker said:

The Ad Astra website talks about a 200 kw powered engine but, to make a trip to Mars in three weeks, or even the often quoted 39 days, how much power would be needed? Would that be in the realm of fusion power?

 

The RF can be generated by solar power, fission or fusion. I saw the one to three weeks quoted the other day, sounds far fetched, I know. Fusion for propulsion is a lot easier than fusion for Earthbound power generation of course. 39 days would do just fine though, a lot better than 6 months plus. Less radiation exposure for the astronauts. 

Edited December 17, 2023 by martin-w

[dave2013 1,191]

I'll make a prediction vis-a-vis a manned Mars expedition:

It won't happen until after 2035, and the chances of it even happening after 2035 but before 2040 is about 50% IMO.

Fusion engines are currently pie in the sky, and practical nuclear propulsion is at least 10 years away and likely longer, and that's only if NASA or whoever gets enough money to continue developing it.

I love imagining this stuff like manned Mars missions, permanent bases on the moon, manned missions to the asteroid belt, etc., but when I realistically consider what it actually takes to do all this, not to mention the cost, it forces me to realize that it just ain't gonna happen for another 15+ years, if at all.

The VASIMIR engines sounds promising and is the most viable IMO.  The nuclear thermal propulsion is dangerous due to having to use a fission reactor to heat a liquid hydrogen propellant, and I just don't see NASA putting humans on what amounts to a nuclear-powered Hindenburg in space.  The problem with VASIMIR is that so far it has only produced 5 Newtons of thrust using 200kW of power.  5N is not enough thrust to accelerate anything but a tiny space probe.  It would take tens of thousands of Newtons to accelerate a manned spacecraft, which means hundreds of thousands of kilowatts of electric power - what's going to produce that much electricity, and how much will it weigh?

Sorry, but this stuff is still in its infancy and won't be ready for decades.  Remember that there's a big difference between science performed in a laboratory and *applied science* - the applied part is usually a lot more difficult.

Dave

[birdguy 4,013]

Self scan checkout lanes are being abandoned by some chain stores because they contribute to increased shoplifting.

https://www.businessinsider.com/self-checkout-theft-is-a-bigger-problem-than-retailers-thought-2023-12?op=1

Noel

[martin-w 3,370]

57 minutes ago, dave2013 said:

I'll make a prediction vis-a-vis a manned Mars expedition:

It won't happen until after 2035, and the chances of it even happening after 2035 but before 2040 is about 50% IMO.

 

Difficult to predict. NASA are saying 2030's and are advancing the technology with that time frame in mind. Nobody can definitively say though, too many variables. All it takes is an administration to get into power that's against the program and it can be curtailed.

 

https://www.nasa.gov/humans-in-space/humans-to-mars/#:~:text=NASA is advancing many technologies,to the Red Planet possible.

 

57 minutes ago, dave2013 said:

Fusion engines are currently pie in the sky, and practical nuclear propulsion is at least 10 years away and likely longer, and that's only if NASA or whoever gets enough money to continue developing it.

 

As mentioned, NASA, Lockheed Martin, Rolls Royce, DARPA and others are currently working on NTP. The goal is to have it ready for the 20030's Mars mission. So ten years away, as you mention, would be perfect. 👍

 

57 minutes ago, dave2013 said:

he nuclear thermal propulsion is dangerous due to having to use a fission reactor to heat a liquid hydrogen propellant, and I just don't see NASA putting humans on what amounts to a nuclear-powered Hindenburg in space.

 

Well, you better tell NASA then, because that's precisely what the intention is and that's precisely the technology they are progressing. If its properly designed it won't be excessively dangerous. Rolls Royce and others are developing small nuclear reactors that fit the bill. 

 

57 minutes ago, dave2013 said:

Fusion engines are currently pie in the sky, 

 

Pulsar Fusion are working on it. Currently they manufacture some pretty impressive ion engines. They are saying 2027 for an orbital demonstration. they are currently on Phase 3, the manufacture of the Direct  Fusion Drive. 

 

https://pulsarfusion.com/#:~:text=2027 Orbital Demonstration,Oxide (REBCO) superconducting magnets.

Edited December 17, 2023 by martin-w

[dmwalker 614]

1 hour ago, dave2013 said:

I just don't see NASA putting humans on what amounts to a nuclear-powered Hindenburg in space.

Without oxygen, hydrogen isn't flammable. It needs 24% to 96% air in order to form a flammable mixture. Outside that range, it doesn't burn. The only oxygen available would be in the breathing air, which, I imagine would be well separated from the hydrogen. Conventionally powered spaceships would be more like the Hindenburg since they carry both chemicals required for combustion.

Also, I think i read that it doesn't have to be hydrogen. I think there's a range of gases which could be suitable but maybe hydrogen is the most readily available in the quantities required.

Edited December 17, 2023 by dmwalker

[dmwalker 614]

11 hours ago, martin-w said:

most supermarkets now have the scan as you shop system

What happens if a shopper scans only half of the items going into the cart, for example?

[birdguy 4,013]

3 hours ago, dmwalker said:

What happens if a shopper scans only half of the items going into the cart, for example?

If nobody is watching I guess the shopper gets half the groceries for nothing.  Maybe someone at the door can check the merchandise against the sales slip.  But if the shop is crowded it would take a lot of employees to check the carts going out.  That would defeat the purpose of scanning.

Noel

[martin-w 3,370]

8 hours ago, birdguy said:

If nobody is watching I guess the shopper gets half the groceries for nothing.  Maybe someone at the door can check the merchandise against the sales slip.  But if the shop is crowded it would take a lot of employees to check the carts going out.  That would defeat the purpose of scanning.

Noel

 

For basic self scan, small checkouts, you place the item on scales, so it knows if you've scanned or not. There are always staff monitoring, in case somebody slips an item into a different bag. 

For the supermarket self scan, where you scan with the hand scanner as you walk around the supermarket, there are random checks when you scan the barcode at the checkout.

Me and my daughter had one yesterday. It alerts you to a random bag check and the person on duty scans the number of items the system asked to be checked. If an item hasn't been scanned, then they scan all items by hand. Everybody slips up occasionally, no action is taken if you've missed an item or two. 

No sign of them being taken out in the UK as far as I know, and certainly not in Guernsey. If anything, they are multiplying. 

Items lost to theft probably amount to less than the cost of emplying dozens of manual checkout operators. 

Edited December 18, 2023 by martin-w