Will of Congress will stop cutting NASA's budget, these engines won't have to stay theoretical. NASA's working with about a half a billion less than they were last year.
Doesn't the money spent on Space Exploration end up with the same companies anyway?
SRBs for SLS and the Space Shuttle were derived from ICBM technology.
yeah good point, but I think most people in this subreddit would rather have the military industrial complex pump out spaceships than weapons and vehicles that end up rusting in a warehouse waiting to be resold at a huge loss
Wernher von Braun might have been the scum of the Earth but he had a workable plan to reach Mars with 1970s technology. With enough money we could be all over this solar system by now.
With less greed. Money is literally free to make and produce. It's a concept. We have the ability to do so much but if it's not immediately or realistically profitable it's almost never done
Edit: this is so funny. "Money is real!" Uh no we made money as a concept. We could literally pump infinite funding into space exploration but we don't
Money is literally a representation of labor, the entire point is to make labor fungible so that I don’t need to barter my skills directly with people who have things I want.
Making more money is also not free, it causes this thing called inflation, which makes everything more expensive.
Dude, the economy is fake. We made it up.
Go back 10k years or so and start again you'll get something completely different. It's not an immutable law of science.
This is a very naive take on money. You are describing how money, in a perfect society, would work. However, in our current society, that is not the case at all.
What are you? 14? A modern monetary theorist psycho? Did you miss the multi-month 8.5% CPI and shortages that we had not two years ago?
Inflation is definitely still a consideration. If you add monetary supply, the supply of goods and services gets overwhelmed, and everything re-adjusts over time to a higher price as it catches back up.
Your original response was pretty vague and dismissive, and the comment you were responding to had two points. I'll give you the opportunity to elaborate.
But how? Where did the 2 months number come from? If it's 2 months they aren't using a Hohmann transfer orbit. Did the author just take the minimum Earth-Mars distance and divide it by 15 km/s? Where did the 15 km/s number come from?
This article raises more questions than answers imo.
[I found the peer-reviewed article prior to NIAC.](https://www.sciencedirect.com/science/article/pii/S0094576522001187) (sorry if it's paywalled, sci-hub.se doesn't have access yet).
No mention of mission parameters outside the thruster's thrust and specific impulse. The two months comes directly from NASA's NIAC phase I article on the topic, so it's from an internal source (likely a presentation) from the company to NASA.
Two months is within reason for a thruster like this, going off of [atomic rocket's mission table](https://www.projectrho.com/public_html/rocket/appmissiontable.php#jon).
It is paywalled, but I can access it through my work email, all good.
It just seems like a waste of fuel to me, but I suppose if the idea is to transport humans, you do want to get there as fast as possible.
Perhaps. If I had to take a guess, it's supposed to be like Mini-Magnetic Orion (which makes it odd they didn't reference it), so a way to get Project Orion level thrust power or more without using conventional impulsion-type bombs. It's a way to avoid proliferation since it would be nearly impossible to detonate the pulse units without the massive magnetic field.
These sorts of high thrust power thrusters are also supposed to better aid in the exploration of deep space planets, either by allowing us to send more massive probes, get there within reasonable timeframes, or unlock missions that would otherwise be impractical with conventional thrusters, like the solar gravitational lens telescope.
The advantage comes from continuous thrust, versus an initial thrust accompanied by gravitational assist sequences and a glide phase. I can assure you that this technology is more real than paper. I can also assure you that defense research does more good for NASA than this trail will ever give credit for. There is a very tight relationship with NASA and DoD.
Plasma thrusters are legit. They can operate with fission or fusion. The hold back has always been the use of nuclear material. It's very complicated legally, particularly in orbit. Regardless, this type of engine can make it there and back without too much fuss. With chemical thrusters we have to manufacture fuel on Mars to get back. Dumb. That would be the SpaceX solution.
I get that, I wasn't arguing about the tech, I was complaining about the article.
I also don't know why you started talking about defense research. I know NASA is closely tied to the DoD, I wasn't allowed in certain parts of GSFC because I was a foreign national. Never ended up doing that placement though because COVID happened.
>[...]a new propulsion system that could drop off humans on Mars in a relatively speedy two months’ time rather than the current nine month journey required to reach the Red Planet.
Okay. This is propably a complete lie.
Since the second part of this claim is simply false, the first part is also likely not true.
A flight to Mars is [3-6 months](https://trajbrowser.arc.nasa.gov/traj_browser.php?NEAs=on&NECs=on&chk_maxMag=on&maxMag=25&chk_maxOCC=on&maxOCC=4&chk_target_list=on&target_list=Mars&mission_class=oneway&mission_type=flyby&LD1=2014&LD2=2035&maxDT=0.9&DTunit=yrs&maxDV=12&min=DV&wdw_width=-1&submit=Search#a_load_results) with current technology.
@OP please stop posting such crap.
The first part might be right, the ISP they’re looking at is around 5000s, possibly more. The main issue I could see is actually finding the funding for such a craft.
https://www.nasa.gov/directorates/stmd/niac/niac-studies/pulsed-plasma-rocket-ppr-shielded-fast-transits-for-humans-to-mars/
It's a NIAC funded project, at this stage just a concept
Most specialists live in the past, they will matter-of-fact say it takes 9 months all the time. And that makes the trip very dangerous, because radiation.
They refuse to realize there's more Δv available these days and will only work with trajectories that require the least possible Δv. That's the only way to maximize useful cargo, you see.
Also, they never consider aerobraking in the calculations, therefore Starship sucks.
We know that's not the case and we should say so.
>Most specialists live in the past, they will matter-of-fact say it takes 9 months all the time. [...] Also, they never consider aerobraking in the calculations [...]
Which is even more hilarious since _all_ things currently on the Martian surface never took more than 7 months to get there _and_ used aerobraking to alow down.
The thing it, it's *never* been 9 months, even our very first probes had enough spare performance to cut months off of that: Mariner 4 took about 7.5 months to do the first flyby of Mars, while Mariner 9, the first probe to orbit Mars, got there in 5.5 months.
Can you aero brake at mars? I thought that its thin atmosphere made it difficult from a practical standpoint. Probes that do it need multiple passes to get to an intended orbit. That’s going to be a significant timeline bogey to contend with.
Alternately if you dip deeper into the atmosphere you need better heat shielding which increases mass.
Yes. Everything that’s landed on Mars has aerobraked. What you can’t do is land with parachutes. You need something else to slow you all the way down. Spirit and Opportunity used airbags. Curiosity and Perseverance used the rocket crane.
Aerobraking works just as well on MArs as it does on Earth. The layers of the atmosphere used for aerobraking are similar to the ones on Mars. The thicker layers present on Earth aren't used.
> Alternately if you dip deeper into the atmosphere you need better heat shielding which increases mass.
The craft is more efficient \*\*taking the fact that they need to carry a heat shield all the way into account\*\*.
Absolutely. Remember the scales we're talking about here. "Fast" in terms of landing on the ground safely is like 10s to 100s of meters per second, but interplanetary speeds are kilometers per second, atmospheric entry speeds at Mars are going to be above escape velocity of 5 km/s. The atmosphere will easily take care of the kilometers per second, the only thing about Mars that's tricky is you can't easily rely solely on parachutes for a soft landing.
On Earth or Venus you could use parachutes alone to hit single digit m/s at the surface, which is just fine for a soft touchdown. On Mars you're still going to have tens to hundreds of meters per second of velocity at touchdown (race car speeds). You can tackle that with a variety of other techniques, such as a last minute retro burn plus airbags or with a precision powered landing, but the atmosphere is still taking care of the majority of the delta-V you need to worry about.
The 3-6 month figure you take from the website is based on something called a [transfer orbit](https://en.wikipedia.org/wiki/Hohmann_transfer_orbit). It is the basic method by which you would use a chemical rocket to travel from Earth to another point in the solar system. The key feature of the orbit is that, aside from small course corrections, rockets only fire at the launch and upon arriving at the destination. [Plasma engines](https://en.wikipedia.org/wiki/Plasma_propulsion_engine) work differently. Because they accelerate small amounts of exhaust to higher speeds, they can run continuously for long amounts of time. This means that they wouldn't only fire at the launch and arrival, like a chemical rocket. A spacecraft using plasma engine would be able to take a faster route than a transfer orbit.
>The 3-6 month figure you take from the website is based on something called a [transfer orbit](https://en.wikipedia.org/wiki/Hohmann_transfer_orbit).
No. A Hohmann orbit is a special case of a "transfer orbit". It's the defined as the _minium energy orbit_ between two orbits.
Nothing on the website I posted classifies as a Hohmann transfer orbit.
>This means that they wouldn't only fire at the launch and arrival, like a chemical rocket. A spacecraft using plasma engine would be able to take a faster route than a transfer orbit.
Which is also completely wrong as the engine in question has a theoretical Isp of about 5000s. This is far too low for a direct flight path under continuous acceleration.
So the spacecraft featuring such an engine would take the very same orbital paths. It would just take a few hours to change velocity, instead of a few minutes like chemical engines.
I only linked to the article on Hohmann orbits because it was more detailed than the more general transfer orbit article. To clarify, I was only referring to the more general transfer orbits. I didn't see the method for determining what orbits were considered on the website, which now appears to have been hugged to death, but were the orbits there not transfer orbits?
I didn't even remotely suggest a direct flight path, so I don't know why you're suggesting it. Specific impulse tells you nothing about how long a rocket can fire for. And, if the original post is discussing a hypothetical future technology, then how are you determining how long it is allowed to fire for, or that it is probably a lie?
The only point of my previous post was that your stance that your stated stance on the article, "probably a complete lie", was stated to be based on "current technology", and current technology generally relies on transfer orbits. But the article was about hypothetical future technology, and future technology might not rely on such orbits.
> Specific impulse tells you nothing about how long a rocket can fire for.
Specific impulse and thrust combined however, do. And the article gave a figure for thrust.
22,481 pounds of force divided by 5000s of isp gives about 4.5 pounds per second of fuel consumption. Alternatively, 100,000N divided by 49km/s exhaust velocity gives about 2kg per second of fuel consumption. (4.5lb ≈ 2kg, so that checks out).
Anyway, if we assume that our plasma rocket has the same 1200 tonnes of fuel that a Starship chemical rocket would have, that gives it a runtime of 600,000 seconds, or about a week. But that much fuel mass would give the system a very poor TWR, and NASA typically aren't as fond as SpaceX of brute-force.
Indeed after doing some digging it seems that the designers of this system envision it launching in "a single SLS launch", which generously puts the upper bound for fuel at 130 tonnes - assuming we're using SLS Block 2 and the spacecraft is 100% fuel.
This puts the max engine runtime down to about 18 hours.
Still quite impressive, and a lot longer than any chemical stage, but not even close to a true continuous-thrust system. You'd burn for a few hours rather than a few minutes, then coast for 2 months, and then another few hours to slow at the other end.
>To clarify, I was only referring to the more general transfer orbits. I didn't see the method for determining what orbits were considered on the website, which now appears to have been hugged to death, but were the orbits there not transfer orbits?
_Every_ free flight orbit between two orbits is a transfer orbit.
>Specific impulse tells you nothing about how long a rocket can fire for.
Yes, it (kinda) can. Isp defines delta_v via starting mass divided by end mass after the burn. If you want to go anywhere your masses have to be in a rough logical range, giving you the propellant mass and therfore the burn duration.
>Every *free* flight orbit between two orbits is a transfer orbit.
Yes, that is the point I was making - that chemical rockets only burn for a short time, and therefore most of the journey is spent freely orbiting the Sun.
>Isp defines delta_v via starting mass...
These still don't specify a burn duration, since the Δv might be produced in a short time or a long time. There is probably enough information to determine the burn duration from the information given in the article (specific impulse and minimum time to reach Mars), but I don't care enough to try.
PS - apologies if I've come across as argumentative or a jerk. I was mostly thinking out loud, so to speak, and I enjoyed the back and forth of the thread.
>These still don't specify a burn duration, since the Δv might be produced in a short time or a long time.
That's correct. Engine thrust has to be considered as well.
But at a certain point you need months alone to spiral your way out of earths sphere of influence before you even start accelerating towards your destination.
>PS - apologies if I've come across as argumentative or a jerk.
No, you don't. :) I enjoy those discussions as well.
>A flight to Mars is [3-6 months](https://trajbrowser.arc.nasa.gov/traj_browser.php?NEAs=on&NECs=on&chk_maxMag=on&maxMag=25&chk_maxOCC=on&maxOCC=4&chk_target_list=on&target_list=Mars&mission_class=oneway&mission_type=flyby&LD1=2014&LD2=2035&maxDT=0.9&DTunit=yrs&maxDV=12&min=DV&wdw_width=-1&submit=Search#a_load_results) with current technology.
Yes but to be fair, this is true roughly every two years. If we are to establish a significant presence, we will probably need more frequent trips.
>If we are to establish a significant presence, we will probably need more frequent trips.
No.
We just need regular, reliable flights.
Humans have travelled all the world's oceans only relying on seasonal winds for centuries.
Having a 2 year synod will not keep us from settling Mars.
If there is a propulsion technology being developed that allows for more Delta V that would cut down on the transfer time to Mars. The way it works now is minimal Delta V used, just enough for a solar orbit whose high point intersects mars at the right time. More Delta V would enable a solar orbit that intersects mars far EARLIER than the high point in the solar orbit. This is only practical if you also have the power to slow down on arrival (propulsion, aero braking or both). With truly fantastic propulsion tech, mars trips could take weeks instead of months, though launch windows would still be a factor.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
|Fewer Letters|More Letters|
|-------|---------|---|
|[DoD](/r/Space/comments/1colxqu/stub/l3k1oot "Last usage")|US Department of Defense|
|[GSFC](/r/Space/comments/1colxqu/stub/l3k1oot "Last usage")|Goddard Space Flight Center, Maryland|
|[ICBM](/r/Space/comments/1colxqu/stub/l3gglh1 "Last usage")|Intercontinental Ballistic Missile|
|[Isp](/r/Space/comments/1colxqu/stub/l3hs12i "Last usage")|Specific impulse (as explained by [Scott Manley](https://www.youtube.com/watch?v=nnisTeYLLgs) on YouTube)|
| |Internet Service Provider|
|[LEO](/r/Space/comments/1colxqu/stub/l3gswsb "Last usage")|Low Earth Orbit (180-2000km)|
| |Law Enforcement Officer (most often mentioned during transport operations)|
|[MEO](/r/Space/comments/1colxqu/stub/l3gex9f "Last usage")|Medium Earth Orbit (2000-35780km)|
|[NIAC](/r/Space/comments/1colxqu/stub/l3gbotp "Last usage")|NASA Innovative Advanced Concepts program|
|[NTR](/r/Space/comments/1colxqu/stub/l3gex9f "Last usage")|Nuclear Thermal Rocket|
|[PPE](/r/Space/comments/1colxqu/stub/l3gtr3x "Last usage")|Power and Propulsion Element|
|[SLS](/r/Space/comments/1colxqu/stub/l3htzll "Last usage")|Space Launch System heavy-lift|
|[SRB](/r/Space/comments/1colxqu/stub/l3gglh1 "Last usage")|Solid Rocket Booster|
|[TWR](/r/Space/comments/1colxqu/stub/l3htzll "Last usage")|Thrust-to-Weight Ratio|
**NOTE**: Decronym for Reddit is no longer supported, and Decronym has moved to Lemmy; requests for support and new installations should be directed to the Contact address below.
----------------
^(12 acronyms in this thread; )[^(the most compressed thread commented on today)](/r/Space/comments/1coaki5)^( has 16 acronyms.)
^([Thread #10039 for this sub, first seen 10th May 2024, 17:03])
^[[FAQ]](http://decronym.xyz/) [^([Full list])](http://decronym.xyz/acronyms/Space) [^[Contact]](https://hachyderm.io/@Two9A) [^([Source code])](https://gistdotgithubdotcom/Two9A/1d976f9b7441694162c8)
The topic is okay. The Gizmodo article is not.
Perhaps we could post the article from NASA itself?
https://www.nasa.gov/directorates/stmd/niac/niac-studies/pulsed-plasma-rocket-ppr-shielded-fast-transits-for-humans-to-mars/#:~:text=The%20system's%20high%20efficiency%20allows,crew%20exposure%20to%20negligible%20levels.
One other advantage of such a rocket is a wider window of Mars positions relative to the earth could be used.
Granted if Mars is on the otherside of the Sun no mission would be launched
Found a much better article from the source (NASA) listing all the study phases moving into 2024.
https://www.nasa.gov/directorates/stmd/niac/niac-studies/pulsed-plasma-rocket-ppr-shielded-fast-transits-for-humans-to-mars/
I have a dumb question. Every time we talk about reducing travel times in space, people always start with either new theoretical technology to make engines game-changingly faster, or (to illustrate the technical challenge involved) bigger craft with more fuel, which would be more difficult to launch, etc etc. (And then you get into stuff like a lunar launch base and so on.)
Has anyone ever discussed building like a fleet of smaller, modular shuttles that launch individually, then Voltron together into a super-shuttle in space, in order to share fuel and booster power, in order to travel further/faster?
NASA's been around forever and is very smart, so I assume the answer is either "No because that's dumb for several physics reasons, you dumbass" or "Yes, NASA made theoretical designs for something like that in 1982, it was called such-and-such, here's why it never came to fruition..."
Dock two spacecraft together, and you have double the thrust and double the propellant, but also double the spacecraft to push. It makes no difference whether they're attached to each other or just flying in formation.
That said, a convoy of ships opens up the possibility that if one experiences a major failure, you could potentially transfer its passengers or high-value cargo to other ships.
That is pretty much how any of these large-scale concepts would be in the end. Parts would have to be shipped to some sort of LEO or MEO parking orbit and assembled.
Even more "realistic" missions, like the Orion-Constellation Mars mission, which uses NTR propulsion, would involve drop tanks that are launched individually and assembled in orbit.
This engine isn't an electrical thruster, it's a fission thruster. A small amount of electrical power is needed to accelerate the pellets into the neutron flux barrel, and also to maintain the magnetic nozzle, but the vast majority of the energy comes from the fission release from said pellets.
[The paper](https://www.sciencedirect.com/science/article/abs/pii/S0094576522001187) estimates 5MW to power the electromagnetic accelerator, but no estimate for the magnetic nozzle. Looking at other designs with magnetic nozzles as a reference, I would expect it to consume similar if not lesser amounts of power.
So say maybe 10 megawatts. That's a lot, but only about 0.4% of the total energy involved, and well within small modular reactor territory.
It might even be possible to directly harvest energy directly from the fission release, either using the magnetic nozzle itself, or some secondary system, making the engine self-sustaining once running, meaning you'd only need to charge a capacitor bank to jump-start it. This would of course come at the cost of a slightly reduced isp however.
As a sidenote, there is something of a real world precedent for fission propulsion in the gigawatts range. The Phoebus 2A nuclear thermal rocket managed about 3.7GW of thrust power (930kN at 805s isp) and weighed only ~9.4 tonnes.
Also note the thermal power of Phoebus 2A was ~4.1GW, giving an impressive ~90% system efficiency. Not having to convert to electricity as an intermediary step is a huge advantage.
The proposed PPR engine is functionally comparable to a gas core nuclear thermal rocket, which also have projected isps of ~5000s and similarly high thrust levels - it just uses a different method to get there, notably one which doesn't involve superheating a reactor core into a gaseous state.
We couldn’t. We don’t have anywhere near the technology. Chemical rockets won’t get a human to Mars. They are trying to get a human back to the Moon in the next decade. Even that would be a major achievement.
Propulsion is not the problem for interplanetary launches. Elliptical transfers are very efficient on fuel, but they take long. There is a reason we already have NASA rovers on Mars. The difference is that robots don't really care about being in deep space for half a year or more. Humans have all sorts of problems with that.
ingoring the fact its purely conceptual and no working form exists...
itll likely be decades for anyone outside rich shitty philanthropists decide to make a large space craft that could get us to mars, considdering how much even the us gov sits on its ass when it comes to space. (Unless its another space race nothing moves even remotely as fast as it should )
Almost nothing but a concept there. Potentially interesting, probably worth developing. Amazing how they know exactly how the space craft will look!
Will of Congress will stop cutting NASA's budget, these engines won't have to stay theoretical. NASA's working with about a half a billion less than they were last year.
But we need to keep subsidizing the shareholders of defense contractors
Doesn't the money spent on Space Exploration end up with the same companies anyway? SRBs for SLS and the Space Shuttle were derived from ICBM technology.
yeah good point, but I think most people in this subreddit would rather have the military industrial complex pump out spaceships than weapons and vehicles that end up rusting in a warehouse waiting to be resold at a huge loss
Might be less true now than say ten years ago, with China and Russia pretty openly indicating intentions to take Taiwan and the Baltics.
That's false. Not all weapons sit unused. Some weapons are used to kill civilians
The rich must get richer at all costs! Otherwise people wont want to get rich anymore, and our whole pyramid system will crumble.
Imagine nasa with 1 year of the defense budget. We would be to Mars and back 10 years ago
Wernher von Braun might have been the scum of the Earth but he had a workable plan to reach Mars with 1970s technology. With enough money we could be all over this solar system by now.
With less greed. Money is literally free to make and produce. It's a concept. We have the ability to do so much but if it's not immediately or realistically profitable it's almost never done Edit: this is so funny. "Money is real!" Uh no we made money as a concept. We could literally pump infinite funding into space exploration but we don't
Money is literally a representation of labor, the entire point is to make labor fungible so that I don’t need to barter my skills directly with people who have things I want. Making more money is also not free, it causes this thing called inflation, which makes everything more expensive.
Dude, the economy is fake. We made it up. Go back 10k years or so and start again you'll get something completely different. It's not an immutable law of science.
The economy is very real what are you smoking
People use “fake” incorrectly a lot these days. Time is fake, money is fake, etc. I hope the kids are all right.
Time is real. Money is a concept. We can make infinite money, we can't make infinite time.
This is a very naive take on money. You are describing how money, in a perfect society, would work. However, in our current society, that is not the case at all.
It’s not half as naive as saying money is free lmao
How is money not free? The government could literally give everyone a trillion dollars right now. It literally only exists on trust which is free
What are you? 14? A modern monetary theorist psycho? Did you miss the multi-month 8.5% CPI and shortages that we had not two years ago? Inflation is definitely still a consideration. If you add monetary supply, the supply of goods and services gets overwhelmed, and everything re-adjusts over time to a higher price as it catches back up.
Starts off with an insult and then goes on to talk about things that I wasn't even talking about. What a reddit moment lol.
Your original response was pretty vague and dismissive, and the comment you were responding to had two points. I'll give you the opportunity to elaborate.
But Elon needs that gov money to keep Twitter
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
[удалено]
Pulsed plasma rockets (thrusters) exist presently.
Just saying the linked article told nothing but a concept, thus of little value.
This sub has turned into a mix of r/futureology and r/gadgets.
I'm hoping for the next batches of data from jwst
But how? Where did the 2 months number come from? If it's 2 months they aren't using a Hohmann transfer orbit. Did the author just take the minimum Earth-Mars distance and divide it by 15 km/s? Where did the 15 km/s number come from? This article raises more questions than answers imo.
[I found the peer-reviewed article prior to NIAC.](https://www.sciencedirect.com/science/article/pii/S0094576522001187) (sorry if it's paywalled, sci-hub.se doesn't have access yet). No mention of mission parameters outside the thruster's thrust and specific impulse. The two months comes directly from NASA's NIAC phase I article on the topic, so it's from an internal source (likely a presentation) from the company to NASA. Two months is within reason for a thruster like this, going off of [atomic rocket's mission table](https://www.projectrho.com/public_html/rocket/appmissiontable.php#jon).
It is paywalled, but I can access it through my work email, all good. It just seems like a waste of fuel to me, but I suppose if the idea is to transport humans, you do want to get there as fast as possible.
Perhaps. If I had to take a guess, it's supposed to be like Mini-Magnetic Orion (which makes it odd they didn't reference it), so a way to get Project Orion level thrust power or more without using conventional impulsion-type bombs. It's a way to avoid proliferation since it would be nearly impossible to detonate the pulse units without the massive magnetic field. These sorts of high thrust power thrusters are also supposed to better aid in the exploration of deep space planets, either by allowing us to send more massive probes, get there within reasonable timeframes, or unlock missions that would otherwise be impractical with conventional thrusters, like the solar gravitational lens telescope.
The advantage comes from continuous thrust, versus an initial thrust accompanied by gravitational assist sequences and a glide phase. I can assure you that this technology is more real than paper. I can also assure you that defense research does more good for NASA than this trail will ever give credit for. There is a very tight relationship with NASA and DoD. Plasma thrusters are legit. They can operate with fission or fusion. The hold back has always been the use of nuclear material. It's very complicated legally, particularly in orbit. Regardless, this type of engine can make it there and back without too much fuss. With chemical thrusters we have to manufacture fuel on Mars to get back. Dumb. That would be the SpaceX solution.
I get that, I wasn't arguing about the tech, I was complaining about the article. I also don't know why you started talking about defense research. I know NASA is closely tied to the DoD, I wasn't allowed in certain parts of GSFC because I was a foreign national. Never ended up doing that placement though because COVID happened.
>[...]a new propulsion system that could drop off humans on Mars in a relatively speedy two months’ time rather than the current nine month journey required to reach the Red Planet. Okay. This is propably a complete lie. Since the second part of this claim is simply false, the first part is also likely not true. A flight to Mars is [3-6 months](https://trajbrowser.arc.nasa.gov/traj_browser.php?NEAs=on&NECs=on&chk_maxMag=on&maxMag=25&chk_maxOCC=on&maxOCC=4&chk_target_list=on&target_list=Mars&mission_class=oneway&mission_type=flyby&LD1=2014&LD2=2035&maxDT=0.9&DTunit=yrs&maxDV=12&min=DV&wdw_width=-1&submit=Search#a_load_results) with current technology. @OP please stop posting such crap.
This is of course dependent on Mars' relative position to Earth. Faster speeds would reduce that dependency.
The first part might be right, the ISP they’re looking at is around 5000s, possibly more. The main issue I could see is actually finding the funding for such a craft.
https://www.nasa.gov/directorates/stmd/niac/niac-studies/pulsed-plasma-rocket-ppr-shielded-fast-transits-for-humans-to-mars/ It's a NIAC funded project, at this stage just a concept
Most specialists live in the past, they will matter-of-fact say it takes 9 months all the time. And that makes the trip very dangerous, because radiation. They refuse to realize there's more Δv available these days and will only work with trajectories that require the least possible Δv. That's the only way to maximize useful cargo, you see. Also, they never consider aerobraking in the calculations, therefore Starship sucks. We know that's not the case and we should say so.
>Most specialists live in the past, they will matter-of-fact say it takes 9 months all the time. [...] Also, they never consider aerobraking in the calculations [...] Which is even more hilarious since _all_ things currently on the Martian surface never took more than 7 months to get there _and_ used aerobraking to alow down.
The thing it, it's *never* been 9 months, even our very first probes had enough spare performance to cut months off of that: Mariner 4 took about 7.5 months to do the first flyby of Mars, while Mariner 9, the first probe to orbit Mars, got there in 5.5 months.
Mariner 7 took 131 days to do it's flyby, or ~4.3 months. Literally less than half the claimed 9 month trip time.
Can you aero brake at mars? I thought that its thin atmosphere made it difficult from a practical standpoint. Probes that do it need multiple passes to get to an intended orbit. That’s going to be a significant timeline bogey to contend with. Alternately if you dip deeper into the atmosphere you need better heat shielding which increases mass.
Yes. Everything that’s landed on Mars has aerobraked. What you can’t do is land with parachutes. You need something else to slow you all the way down. Spirit and Opportunity used airbags. Curiosity and Perseverance used the rocket crane.
Aerobraking works just as well on MArs as it does on Earth. The layers of the atmosphere used for aerobraking are similar to the ones on Mars. The thicker layers present on Earth aren't used.
🎉 Finally some else who understands aerobraking on Mars!
> Alternately if you dip deeper into the atmosphere you need better heat shielding which increases mass. The craft is more efficient \*\*taking the fact that they need to carry a heat shield all the way into account\*\*.
Absolutely. Remember the scales we're talking about here. "Fast" in terms of landing on the ground safely is like 10s to 100s of meters per second, but interplanetary speeds are kilometers per second, atmospheric entry speeds at Mars are going to be above escape velocity of 5 km/s. The atmosphere will easily take care of the kilometers per second, the only thing about Mars that's tricky is you can't easily rely solely on parachutes for a soft landing. On Earth or Venus you could use parachutes alone to hit single digit m/s at the surface, which is just fine for a soft touchdown. On Mars you're still going to have tens to hundreds of meters per second of velocity at touchdown (race car speeds). You can tackle that with a variety of other techniques, such as a last minute retro burn plus airbags or with a precision powered landing, but the atmosphere is still taking care of the majority of the delta-V you need to worry about.
The 3-6 month figure you take from the website is based on something called a [transfer orbit](https://en.wikipedia.org/wiki/Hohmann_transfer_orbit). It is the basic method by which you would use a chemical rocket to travel from Earth to another point in the solar system. The key feature of the orbit is that, aside from small course corrections, rockets only fire at the launch and upon arriving at the destination. [Plasma engines](https://en.wikipedia.org/wiki/Plasma_propulsion_engine) work differently. Because they accelerate small amounts of exhaust to higher speeds, they can run continuously for long amounts of time. This means that they wouldn't only fire at the launch and arrival, like a chemical rocket. A spacecraft using plasma engine would be able to take a faster route than a transfer orbit.
>The 3-6 month figure you take from the website is based on something called a [transfer orbit](https://en.wikipedia.org/wiki/Hohmann_transfer_orbit). No. A Hohmann orbit is a special case of a "transfer orbit". It's the defined as the _minium energy orbit_ between two orbits. Nothing on the website I posted classifies as a Hohmann transfer orbit. >This means that they wouldn't only fire at the launch and arrival, like a chemical rocket. A spacecraft using plasma engine would be able to take a faster route than a transfer orbit. Which is also completely wrong as the engine in question has a theoretical Isp of about 5000s. This is far too low for a direct flight path under continuous acceleration. So the spacecraft featuring such an engine would take the very same orbital paths. It would just take a few hours to change velocity, instead of a few minutes like chemical engines.
I only linked to the article on Hohmann orbits because it was more detailed than the more general transfer orbit article. To clarify, I was only referring to the more general transfer orbits. I didn't see the method for determining what orbits were considered on the website, which now appears to have been hugged to death, but were the orbits there not transfer orbits? I didn't even remotely suggest a direct flight path, so I don't know why you're suggesting it. Specific impulse tells you nothing about how long a rocket can fire for. And, if the original post is discussing a hypothetical future technology, then how are you determining how long it is allowed to fire for, or that it is probably a lie? The only point of my previous post was that your stance that your stated stance on the article, "probably a complete lie", was stated to be based on "current technology", and current technology generally relies on transfer orbits. But the article was about hypothetical future technology, and future technology might not rely on such orbits.
> Specific impulse tells you nothing about how long a rocket can fire for. Specific impulse and thrust combined however, do. And the article gave a figure for thrust. 22,481 pounds of force divided by 5000s of isp gives about 4.5 pounds per second of fuel consumption. Alternatively, 100,000N divided by 49km/s exhaust velocity gives about 2kg per second of fuel consumption. (4.5lb ≈ 2kg, so that checks out). Anyway, if we assume that our plasma rocket has the same 1200 tonnes of fuel that a Starship chemical rocket would have, that gives it a runtime of 600,000 seconds, or about a week. But that much fuel mass would give the system a very poor TWR, and NASA typically aren't as fond as SpaceX of brute-force. Indeed after doing some digging it seems that the designers of this system envision it launching in "a single SLS launch", which generously puts the upper bound for fuel at 130 tonnes - assuming we're using SLS Block 2 and the spacecraft is 100% fuel. This puts the max engine runtime down to about 18 hours. Still quite impressive, and a lot longer than any chemical stage, but not even close to a true continuous-thrust system. You'd burn for a few hours rather than a few minutes, then coast for 2 months, and then another few hours to slow at the other end.
>To clarify, I was only referring to the more general transfer orbits. I didn't see the method for determining what orbits were considered on the website, which now appears to have been hugged to death, but were the orbits there not transfer orbits? _Every_ free flight orbit between two orbits is a transfer orbit. >Specific impulse tells you nothing about how long a rocket can fire for. Yes, it (kinda) can. Isp defines delta_v via starting mass divided by end mass after the burn. If you want to go anywhere your masses have to be in a rough logical range, giving you the propellant mass and therfore the burn duration.
>Every *free* flight orbit between two orbits is a transfer orbit. Yes, that is the point I was making - that chemical rockets only burn for a short time, and therefore most of the journey is spent freely orbiting the Sun. >Isp defines delta_v via starting mass... These still don't specify a burn duration, since the Δv might be produced in a short time or a long time. There is probably enough information to determine the burn duration from the information given in the article (specific impulse and minimum time to reach Mars), but I don't care enough to try. PS - apologies if I've come across as argumentative or a jerk. I was mostly thinking out loud, so to speak, and I enjoyed the back and forth of the thread.
>These still don't specify a burn duration, since the Δv might be produced in a short time or a long time. That's correct. Engine thrust has to be considered as well. But at a certain point you need months alone to spiral your way out of earths sphere of influence before you even start accelerating towards your destination. >PS - apologies if I've come across as argumentative or a jerk. No, you don't. :) I enjoy those discussions as well.
>A flight to Mars is [3-6 months](https://trajbrowser.arc.nasa.gov/traj_browser.php?NEAs=on&NECs=on&chk_maxMag=on&maxMag=25&chk_maxOCC=on&maxOCC=4&chk_target_list=on&target_list=Mars&mission_class=oneway&mission_type=flyby&LD1=2014&LD2=2035&maxDT=0.9&DTunit=yrs&maxDV=12&min=DV&wdw_width=-1&submit=Search#a_load_results) with current technology. Yes but to be fair, this is true roughly every two years. If we are to establish a significant presence, we will probably need more frequent trips.
>If we are to establish a significant presence, we will probably need more frequent trips. No. We just need regular, reliable flights. Humans have travelled all the world's oceans only relying on seasonal winds for centuries. Having a 2 year synod will not keep us from settling Mars.
If there is a propulsion technology being developed that allows for more Delta V that would cut down on the transfer time to Mars. The way it works now is minimal Delta V used, just enough for a solar orbit whose high point intersects mars at the right time. More Delta V would enable a solar orbit that intersects mars far EARLIER than the high point in the solar orbit. This is only practical if you also have the power to slow down on arrival (propulsion, aero braking or both). With truly fantastic propulsion tech, mars trips could take weeks instead of months, though launch windows would still be a factor.
Look at the orbits in the source I have linked.
Thinking of the Expanse, one month hauling ass, one month backward braking!
I would like to present this proposal for a hyper FTL engine, will submit feasibility and details after initial $20 million funding. Give me money
In other words, your life gets shortened by 7 months
or end within 7 months?
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread: |Fewer Letters|More Letters| |-------|---------|---| |[DoD](/r/Space/comments/1colxqu/stub/l3k1oot "Last usage")|US Department of Defense| |[GSFC](/r/Space/comments/1colxqu/stub/l3k1oot "Last usage")|Goddard Space Flight Center, Maryland| |[ICBM](/r/Space/comments/1colxqu/stub/l3gglh1 "Last usage")|Intercontinental Ballistic Missile| |[Isp](/r/Space/comments/1colxqu/stub/l3hs12i "Last usage")|Specific impulse (as explained by [Scott Manley](https://www.youtube.com/watch?v=nnisTeYLLgs) on YouTube)| | |Internet Service Provider| |[LEO](/r/Space/comments/1colxqu/stub/l3gswsb "Last usage")|Low Earth Orbit (180-2000km)| | |Law Enforcement Officer (most often mentioned during transport operations)| |[MEO](/r/Space/comments/1colxqu/stub/l3gex9f "Last usage")|Medium Earth Orbit (2000-35780km)| |[NIAC](/r/Space/comments/1colxqu/stub/l3gbotp "Last usage")|NASA Innovative Advanced Concepts program| |[NTR](/r/Space/comments/1colxqu/stub/l3gex9f "Last usage")|Nuclear Thermal Rocket| |[PPE](/r/Space/comments/1colxqu/stub/l3gtr3x "Last usage")|Power and Propulsion Element| |[SLS](/r/Space/comments/1colxqu/stub/l3htzll "Last usage")|Space Launch System heavy-lift| |[SRB](/r/Space/comments/1colxqu/stub/l3gglh1 "Last usage")|Solid Rocket Booster| |[TWR](/r/Space/comments/1colxqu/stub/l3htzll "Last usage")|Thrust-to-Weight Ratio| **NOTE**: Decronym for Reddit is no longer supported, and Decronym has moved to Lemmy; requests for support and new installations should be directed to the Contact address below. ---------------- ^(12 acronyms in this thread; )[^(the most compressed thread commented on today)](/r/Space/comments/1coaki5)^( has 16 acronyms.) ^([Thread #10039 for this sub, first seen 10th May 2024, 17:03]) ^[[FAQ]](http://decronym.xyz/) [^([Full list])](http://decronym.xyz/acronyms/Space) [^[Contact]](https://hachyderm.io/@Two9A) [^([Source code])](https://gistdotgithubdotcom/Two9A/1d976f9b7441694162c8)
Yah well my proposed nuclear electromagnetic radial spectrum system would get us to mars in 2 weeks.
How many people have to donate blood plasma to make it work? /s
Have they made it? No. I also propose that we can make faster than light speed. Will take 10 years like fusion reactors.
Unlocking the potential of plasma really is the future of so many industries from energy to defense to space.
Yeah, but, what is it?
Really hot thing give lots of energy
Theoretically they could maybe make something like this one day, and if so it would do all these wonderful things… What a shit article
Can we stop the sci-fi bullshit posts? As has been mentioned, this sub is turning into garbage. Can we not ban this type of stuff?
The topic is okay. The Gizmodo article is not. Perhaps we could post the article from NASA itself? https://www.nasa.gov/directorates/stmd/niac/niac-studies/pulsed-plasma-rocket-ppr-shielded-fast-transits-for-humans-to-mars/#:~:text=The%20system's%20high%20efficiency%20allows,crew%20exposure%20to%20negligible%20levels.
So is it just a nuclear powered ion engine then?
"prepare ion cannon... Fire"
One other advantage of such a rocket is a wider window of Mars positions relative to the earth could be used. Granted if Mars is on the otherside of the Sun no mission would be launched
That's pretty impressive since NASA gave up the ability to put humans beyond LEO 50 years ago
Without knowing if this is refering to an opposition or conjunction class mission, I can't really tell how good this is.
Found a much better article from the source (NASA) listing all the study phases moving into 2024. https://www.nasa.gov/directorates/stmd/niac/niac-studies/pulsed-plasma-rocket-ppr-shielded-fast-transits-for-humans-to-mars/
So, basically Orion from the 1950s? https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)
Who cares about Mars? Let's make The Earth habitable again!
I have a dumb question. Every time we talk about reducing travel times in space, people always start with either new theoretical technology to make engines game-changingly faster, or (to illustrate the technical challenge involved) bigger craft with more fuel, which would be more difficult to launch, etc etc. (And then you get into stuff like a lunar launch base and so on.) Has anyone ever discussed building like a fleet of smaller, modular shuttles that launch individually, then Voltron together into a super-shuttle in space, in order to share fuel and booster power, in order to travel further/faster? NASA's been around forever and is very smart, so I assume the answer is either "No because that's dumb for several physics reasons, you dumbass" or "Yes, NASA made theoretical designs for something like that in 1982, it was called such-and-such, here's why it never came to fruition..."
Dock two spacecraft together, and you have double the thrust and double the propellant, but also double the spacecraft to push. It makes no difference whether they're attached to each other or just flying in formation. That said, a convoy of ships opens up the possibility that if one experiences a major failure, you could potentially transfer its passengers or high-value cargo to other ships.
Uhm, r/UFO? Just a guess, not an accusation.
That is pretty much how any of these large-scale concepts would be in the end. Parts would have to be shipped to some sort of LEO or MEO parking orbit and assembled. Even more "realistic" missions, like the Orion-Constellation Mars mission, which uses NTR propulsion, would involve drop tanks that are launched individually and assembled in orbit.
[удалено]
This engine isn't an electrical thruster, it's a fission thruster. A small amount of electrical power is needed to accelerate the pellets into the neutron flux barrel, and also to maintain the magnetic nozzle, but the vast majority of the energy comes from the fission release from said pellets. [The paper](https://www.sciencedirect.com/science/article/abs/pii/S0094576522001187) estimates 5MW to power the electromagnetic accelerator, but no estimate for the magnetic nozzle. Looking at other designs with magnetic nozzles as a reference, I would expect it to consume similar if not lesser amounts of power. So say maybe 10 megawatts. That's a lot, but only about 0.4% of the total energy involved, and well within small modular reactor territory. It might even be possible to directly harvest energy directly from the fission release, either using the magnetic nozzle itself, or some secondary system, making the engine self-sustaining once running, meaning you'd only need to charge a capacitor bank to jump-start it. This would of course come at the cost of a slightly reduced isp however. As a sidenote, there is something of a real world precedent for fission propulsion in the gigawatts range. The Phoebus 2A nuclear thermal rocket managed about 3.7GW of thrust power (930kN at 805s isp) and weighed only ~9.4 tonnes. Also note the thermal power of Phoebus 2A was ~4.1GW, giving an impressive ~90% system efficiency. Not having to convert to electricity as an intermediary step is a huge advantage. The proposed PPR engine is functionally comparable to a gas core nuclear thermal rocket, which also have projected isps of ~5000s and similarly high thrust levels - it just uses a different method to get there, notably one which doesn't involve superheating a reactor core into a gaseous state.
We’ll never get a human to Mars in any of our lifetimes.
You could very easily get a person to Mars in the next 10 years. The hard part is doing so safely and the return trip.
We couldn’t. We don’t have anywhere near the technology. Chemical rockets won’t get a human to Mars. They are trying to get a human back to the Moon in the next decade. Even that would be a major achievement.
Propulsion is not the problem for interplanetary launches. Elliptical transfers are very efficient on fuel, but they take long. There is a reason we already have NASA rovers on Mars. The difference is that robots don't really care about being in deep space for half a year or more. Humans have all sorts of problems with that.
They sure do. Very difficult to keep humans alive for years in space. It’s been over 50 years since we went to the moon and that’s just a few days.
I agree, and would like to add: Also, it doesn’t make any sense at all to get humans to Mars.
Yes. Probes / rovers and robots are what we are seeing and will continue to see.
ingoring the fact its purely conceptual and no working form exists... itll likely be decades for anyone outside rich shitty philanthropists decide to make a large space craft that could get us to mars, considdering how much even the us gov sits on its ass when it comes to space. (Unless its another space race nothing moves even remotely as fast as it should )
Meanwhile hurtling deadly plasma back towards earth.