Given that NASA plans to fly crew on the first-ever mission of the SLS 1B with the Exploration Upper Stage, I’m going to have to say no.
I agree, but the issues are different this time. It is a reflection on the state of science to a large extent and the state of engineering to a much lesser extent. And that is the reliance on models to predict outcomes. Models are only as good as their validation procedures. NASA was, in terms of software, very good at this in the past, from what I’ve read for both Apollo and Space Shuttle I suspect best in class as in world-class. But going forward for SLS, I am concerned how much of this effort was pushed back onto the contractors. And does NASA truly have a handle on how well designed *and validated* the models being used are.? Reliance on modelling vs post flight data analysis is the only explanation I can come up with for flying crew on a first-off of anything.
And if something goes wrong, much like the Columbia accident, no one predicted it, er I mean, no model predicted it, so no big deal right?
and the state of engineering to a much lesser extent.
By this I mean, models and modelers are continuously refining their simulations against experimental measurement, at least in electronic design engineering they do. It’s just way, way too expensive to “get the models wrong” and have to re-do them and everything that depended upon them, eating the NRE along the way.
No. It isn’t fixed. The only thing fixed is NASA’s thinking. They need to launch people on the next one or risk losing funding. Nothing has changed except the names of the people involved.
I suspect their modelling is as good as ever. The problem was management overriding their models predictions after all.
That problem sounds like it hasn’t been fixed. Changing the shape of the d*n table is famously fiddling with things you can do something about to avoid the difficult problems (possibly because delaying helps you).
I like Milt, so it was good to see him quoted. However, I’m not sure the article by Eric Bergen really added any information on today’s safety culture at NASA. It went over the history of that culture during Columbia and before, but now? All we got is that we are hitting the generational mark. So what? It’s been over 10 years since NASA launched astronauts on their own booster in their own capsule, which has gone a long way in making people forget how bad NASA’s safety culture can be.
From Earth, Venus is closest and fastest planet’s orbit
and uses least delta-v to reach from Earth orbit.
Cosmic Train Schedule:
With simple hohmann from Earth to Venus
“Trip Time 0.3999 Years
Total DV 5.2022 km/sec
Back to Earth from Venus orbit, it’s same:
“Trip Time 0.3999 Years Total DV 5.2022 km/sec”
365 days x 0.3999 Years = 145.9635 days
And a simple from Venus to Mars requires more delta-v: 10.5315 km/sec but gets faster to Mars as compared to Earth to Mars. It takes:
0.5954 Years {365 x .5954 = 217.321 days / 30 = 7.244033333 months
Earth’s simple to Mars:
Trip Time: 0.7087 Years [.7087 x 365= 258.6755 days
divided by 30 = 8.622516667 months.
Using non simple [or the least amount delta-v] NASA has arrived at Mars in about 7 month and Musk says by slowing down with Mars atmosphere using Starship
he lower it to around 6 months.
And by using a trajectory other than hohmann- or by using lower and more continuous thrust and more delta-v, a nuclear rocket engine can arrive at Mars from Earth orbit in less than 2 months.
And from Earth to Mars or to Venus with chemical we have done flybies of Venus [or Mars distance] in about
2 month- but difference in relative velocities is too high for chemical rockets to be used.
[The Parker solar probe, left Earth and did gravity assist using Venus [to get closer to the sun] and it took a bit less than 2 months to reach Venus to do the gravity assist].
No one done it the other way, leave from Venus and flyby Earth is about 2 month, but it could be done.
And one could have rare window, where to left Venus, and did gravity assist using Earth and then went to Mars.
And shorten the Venus to Mars travel time [“7.244033333 months”].
So, this roughly a Venus to Mars hohmann transfer, but when you cross Earth’s orbit, Earth is in that location of it’s orbit, and you use Earth’s gravity for a gravity assist.
Or from Venus to Earth it takes 5.2 km/sec and Venus
to Mars takes 10.5 km/sec, so leaving Venus to Mars with about 10 km/sec and you going gain delta-v and change vector from the gravity assist. And doing this to get to Mars faster than 7.2 months {which you could do without using Earth for gravity assist].
Of course another option is adding thrust to this gravity assist {a powered gravity assist].
Wrong thread?
Getting to Mars fast will be a significant NASA safety, issue.
One idea is using nuclear rockets, NASA has always played with that idea- it’s only practical purpose or practical use is related to safety- and it’s not particularly safe.
A nuclear rocket works to get to Mars in 2 months, because in theory it can deliver more delta-v.
So, if can get nuclear rocket to LEO, than it can get
to Mars in fast time or without re-fueling, it go to Mars and return to Earth.
When selling idea of nuclear rocket, they are not compared to refueling chemical rocket in orbit or comparing it to cheap launch cost from Earth to LEO- and both these possibilities, appears to be approaching as reality in the near term.
And in addition, we could refuel chemical rockets in more places than LEO.
Such as in orbit near the Moon, Mars orbit, and Venus orbit.
And related to that, I don’t think having nuclear rocket in LEO is such a good idea- having them only as close as lunar orbit could be more, safe.
But if have rocket fuel in LEO [and can move that rocket fuel elsewhere] is added to delta-v of chemical rockets. And with this added delta-v ability
of chemical rockets, can go to Mars in shorter travel times to increase crew safety.
In terms of coming from Venus to Mars and using Earth as gravity assist and getting to Mars faster,
what you not going to do, is get into Earth to Mars hohmann trajectory- that would take a lot longer to get to Mars. Instead the gravity assist would be about changing the vector of the hohmann trajectory of the Venus to Mars. Though that hohmann without using Earth gravity assist, would get to Mars. Or you could pass near Earth and not get close enough to have much effect from Earth, but I am talking getting closer to Earth using it to gain delta-v, which mostly a vector change {as what is mostly done with typical gravity assists]
And low thrust nuclear is also mostly changing vector- spiraling out- is a continuous vector change- and requires more delta-v compared to hohmann transfers {which is not changing vector, but rather adding or removing delta-v to the velocity].
But what didn’t mention was using Venus orbit is also related to crew safety, because returning to Earth via Venus from Mars can used to get back to Earth quicker. Either as crew abort, or planned short stay of Mars. And in terms abort or planned
one also use Venus orbit for crew medical emergency and also related to possible back contamination “worries”.
Worries which might become a real thing, and options like long time stays on the Moon could be needed. And one could make this, after finding out
it is actual issue- a crash/emergency action type thing, or take steps which enable taking such emergency action with more preliminary actions
so it’s a less frantic emergency- so could be only to have “a significant plan” one could use.
Given that NASA plans to fly crew on the first-ever mission of the SLS 1B with the Exploration Upper Stage, I’m going to have to say no.
I agree, but the issues are different this time. It is a reflection on the state of science to a large extent and the state of engineering to a much lesser extent. And that is the reliance on models to predict outcomes. Models are only as good as their validation procedures. NASA was, in terms of software, very good at this in the past, from what I’ve read for both Apollo and Space Shuttle I suspect best in class as in world-class. But going forward for SLS, I am concerned how much of this effort was pushed back onto the contractors. And does NASA truly have a handle on how well designed *and validated* the models being used are.? Reliance on modelling vs post flight data analysis is the only explanation I can come up with for flying crew on a first-off of anything.
And if something goes wrong, much like the Columbia accident, no one predicted it, er I mean, no model predicted it, so no big deal right?
and the state of engineering to a much lesser extent.
By this I mean, models and modelers are continuously refining their simulations against experimental measurement, at least in electronic design engineering they do. It’s just way, way too expensive to “get the models wrong” and have to re-do them and everything that depended upon them, eating the NRE along the way.
No. It isn’t fixed. The only thing fixed is NASA’s thinking. They need to launch people on the next one or risk losing funding. Nothing has changed except the names of the people involved.
I suspect their modelling is as good as ever. The problem was management overriding their models predictions after all.
That problem sounds like it hasn’t been fixed. Changing the shape of the d*n table is famously fiddling with things you can do something about to avoid the difficult problems (possibly because delaying helps you).
I like Milt, so it was good to see him quoted. However, I’m not sure the article by Eric Bergen really added any information on today’s safety culture at NASA. It went over the history of that culture during Columbia and before, but now? All we got is that we are hitting the generational mark. So what? It’s been over 10 years since NASA launched astronauts on their own booster in their own capsule, which has gone a long way in making people forget how bad NASA’s safety culture can be.
From Earth, Venus is closest and fastest planet’s orbit
and uses least delta-v to reach from Earth orbit.
Cosmic Train Schedule:
With simple hohmann from Earth to Venus
“Trip Time 0.3999 Years
Total DV 5.2022 km/sec
Back to Earth from Venus orbit, it’s same:
“Trip Time 0.3999 Years Total DV 5.2022 km/sec”
365 days x 0.3999 Years = 145.9635 days
And a simple from Venus to Mars requires more delta-v: 10.5315 km/sec but gets faster to Mars as compared to Earth to Mars. It takes:
0.5954 Years {365 x .5954 = 217.321 days / 30 = 7.244033333 months
Earth’s simple to Mars:
Trip Time: 0.7087 Years [.7087 x 365= 258.6755 days
divided by 30 = 8.622516667 months.
Using non simple [or the least amount delta-v] NASA has arrived at Mars in about 7 month and Musk says by slowing down with Mars atmosphere using Starship
he lower it to around 6 months.
And by using a trajectory other than hohmann- or by using lower and more continuous thrust and more delta-v, a nuclear rocket engine can arrive at Mars from Earth orbit in less than 2 months.
And from Earth to Mars or to Venus with chemical we have done flybies of Venus [or Mars distance] in about
2 month- but difference in relative velocities is too high for chemical rockets to be used.
[The Parker solar probe, left Earth and did gravity assist using Venus [to get closer to the sun] and it took a bit less than 2 months to reach Venus to do the gravity assist].
No one done it the other way, leave from Venus and flyby Earth is about 2 month, but it could be done.
And one could have rare window, where to left Venus, and did gravity assist using Earth and then went to Mars.
And shorten the Venus to Mars travel time [“7.244033333 months”].
So, this roughly a Venus to Mars hohmann transfer, but when you cross Earth’s orbit, Earth is in that location of it’s orbit, and you use Earth’s gravity for a gravity assist.
Or from Venus to Earth it takes 5.2 km/sec and Venus
to Mars takes 10.5 km/sec, so leaving Venus to Mars with about 10 km/sec and you going gain delta-v and change vector from the gravity assist. And doing this to get to Mars faster than 7.2 months {which you could do without using Earth for gravity assist].
Of course another option is adding thrust to this gravity assist {a powered gravity assist].
Wrong thread?
Getting to Mars fast will be a significant NASA safety, issue.
One idea is using nuclear rockets, NASA has always played with that idea- it’s only practical purpose or practical use is related to safety- and it’s not particularly safe.
A nuclear rocket works to get to Mars in 2 months, because in theory it can deliver more delta-v.
So, if can get nuclear rocket to LEO, than it can get
to Mars in fast time or without re-fueling, it go to Mars and return to Earth.
When selling idea of nuclear rocket, they are not compared to refueling chemical rocket in orbit or comparing it to cheap launch cost from Earth to LEO- and both these possibilities, appears to be approaching as reality in the near term.
And in addition, we could refuel chemical rockets in more places than LEO.
Such as in orbit near the Moon, Mars orbit, and Venus orbit.
And related to that, I don’t think having nuclear rocket in LEO is such a good idea- having them only as close as lunar orbit could be more, safe.
But if have rocket fuel in LEO [and can move that rocket fuel elsewhere] is added to delta-v of chemical rockets. And with this added delta-v ability
of chemical rockets, can go to Mars in shorter travel times to increase crew safety.
In terms of coming from Venus to Mars and using Earth as gravity assist and getting to Mars faster,
what you not going to do, is get into Earth to Mars hohmann trajectory- that would take a lot longer to get to Mars. Instead the gravity assist would be about changing the vector of the hohmann trajectory of the Venus to Mars. Though that hohmann without using Earth gravity assist, would get to Mars. Or you could pass near Earth and not get close enough to have much effect from Earth, but I am talking getting closer to Earth using it to gain delta-v, which mostly a vector change {as what is mostly done with typical gravity assists]
And low thrust nuclear is also mostly changing vector- spiraling out- is a continuous vector change- and requires more delta-v compared to hohmann transfers {which is not changing vector, but rather adding or removing delta-v to the velocity].
But what didn’t mention was using Venus orbit is also related to crew safety, because returning to Earth via Venus from Mars can used to get back to Earth quicker. Either as crew abort, or planned short stay of Mars. And in terms abort or planned
one also use Venus orbit for crew medical emergency and also related to possible back contamination “worries”.
Worries which might become a real thing, and options like long time stays on the Moon could be needed. And one could make this, after finding out
it is actual issue- a crash/emergency action type thing, or take steps which enable taking such emergency action with more preliminary actions
so it’s a less frantic emergency- so could be only to have “a significant plan” one could use.