StyroCupMan writes "NASA has announced that it will launch a satellite to map our solar system's boundary. It will also study the particles and radiation that pose a health and safety hazard to humans. Time to invest in that shiny new spacesuit."
Re:Historically speaking...
by
iainl
·
· Score: 4, Interesting
The problem, if memory serves, is that it's a lot easier to sling a probe out along the plane than it is to send it "up or down" with any speed - simply because it's being launched from Earth any probe will already have a substantial amount of momentum in the plane.
-- "I Know You Are But What Am I?"
Re:Historically speaking...
by
CrimsonAvenger
·
· Score: 4, Informative
Any scientifically sound reason why this is a bad idea?
DeltaV required to head out perpendicular to the plane of the ecliptic is quite a bit higher than to go out along the ecliptic.
Achieving Solar escape speed from LEO in the plane of the ecliptic is ~9Km/s.
Perpendicular to the ecliptic, deltaV required is ~26Km/s.
And it's tough to use planetary slingshots when you're going out perpendicular to the ecliptic.
--
"I do not agree with what you say, but I will defend to the death your right to say it"
How much will this cost?
by
VoxVeritas
·
· Score: 4, Insightful
I think this is a good idea. I just wish that they would save Hubble. They way they are dealing with Hubble is like junking your car just because it needs a new battery.
Hmmm... my girlfriend tried that logic too...
Re:Long-term science
by
jnik
·
· Score: 4, Informative
Nobody said the probe is actually crossing the termination shock. It's observing ENA's generated at the termination shock.
Uber-brief introduction to energetic neutral atoms: Ions (charged particles) are susceptible to magnetic and electric forces. As a result, they can be boosted to very high energies in certain situations, but also usually can't travel very far before being modified in some way by electromagnetic forces. If, however, an ion interacts with a neutral (charge exchange), it can "steal" one or more electrons from the neutral without substantially changing the energies of either, leaving a nonenergetic ion and an energetic neutral, which then leaves the vicinity as it is no longer subject to EM forces. We can observe these ENA's and infer properties of the acceleration region.
Re:Historically speaking...
by
mopomi
·
· Score: 4, Informative
Basically, an object needs a specific amount of energy to escape the gravitational well of some other object. Remember that kinetic energy is KE = 1/2 mv^2,
where m is mass and v is velocity.
Gravitational binding energy is the energy required to escape a gravity well (basically):
GE = GmM/R,
where G is the gravitational constant, m is the mass of the escaping object, M is the mass of the planet, and R is the planet's radius.
Setting KE=GE and solving for velocity gives you the escape velocity (the very minimum INITIAL velocity required to escape with NO ADDITIONAL ACCELERATION). Notice that the object's mass cancels, so you're left with a constant value for the planet's escape velocity (of course, you need more energy to accelerate a more massive object to the same velocity). Earth's escape velocity is actually 11.1 km/s. Not sure where that 9 km/s comes from.
Re:Historically speaking...
by
CrimsonAvenger
·
· Score: 4, Insightful
Earth's escape velocity is actually 11.1 km/s. Not sure where that 9 km/s comes from.
Read carefully. That was deltaV required to go from LEO (Low Earth Orbit) to Solar escape speed.
It assumes a starting speed of ~8Km/s (Actually, the orbit I assumed had ~7650m/s orbital speed), and a single burn in the direction of both the orbit around the Earth and the Earth's orbit around the Sun. It further assumed Solar escape speed was 42.1Km/s, which is true for a couple points along Earth's orbit, but I'm not sure exactly where, so I won't tell you the dates required for the burn.
If you add 9Km/s to your speed under those conditions, then you will find yourself moving along smartly in the plane of the ecliptic at just over 5250m/s relative to the Sun at some point in the indefinite future, when you are some arbitrarily large distance from the Sun (on the order of two light-months out, give or take a couple light-weeks)
--
"I do not agree with what you say, but I will defend to the death your right to say it"
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The problem, if memory serves, is that it's a lot easier to sling a probe out along the plane than it is to send it "up or down" with any speed - simply because it's being launched from Earth any probe will already have a substantial amount of momentum in the plane.
"I Know You Are But What Am I?"
DeltaV required to head out perpendicular to the plane of the ecliptic is quite a bit higher than to go out along the ecliptic.
Achieving Solar escape speed from LEO in the plane of the ecliptic is ~9Km/s.
Perpendicular to the ecliptic, deltaV required is ~26Km/s.
And it's tough to use planetary slingshots when you're going out perpendicular to the ecliptic.
"I do not agree with what you say, but I will defend to the death your right to say it"
I think this is a good idea. I just wish that they would save Hubble. They way they are dealing with Hubble is like junking your car just because it needs a new battery.
Hmmm... my girlfriend tried that logic too...
Uber-brief introduction to energetic neutral atoms: Ions (charged particles) are susceptible to magnetic and electric forces. As a result, they can be boosted to very high energies in certain situations, but also usually can't travel very far before being modified in some way by electromagnetic forces. If, however, an ion interacts with a neutral (charge exchange), it can "steal" one or more electrons from the neutral without substantially changing the energies of either, leaving a nonenergetic ion and an energetic neutral, which then leaves the vicinity as it is no longer subject to EM forces. We can observe these ENA's and infer properties of the acceleration region.
Basically, an object needs a specific amount of energy to escape the gravitational well of some other object. Remember that kinetic energy is
KE = 1/2 mv^2,
where m is mass and v is velocity.
Gravitational binding energy is the energy required to escape a gravity well (basically):
GE = GmM/R,
where G is the gravitational constant, m is the mass of the escaping object, M is the mass of the planet, and R is the planet's radius.
Setting KE=GE and solving for velocity gives you the escape velocity (the very minimum INITIAL velocity required to escape with NO ADDITIONAL ACCELERATION). Notice that the object's mass cancels, so you're left with a constant value for the planet's escape velocity (of course, you need more energy to accelerate a more massive object to the same velocity). Earth's escape velocity is actually 11.1 km/s. Not sure where that 9 km/s comes from.
Read carefully. That was deltaV required to go from LEO (Low Earth Orbit) to Solar escape speed.
It assumes a starting speed of ~8Km/s (Actually, the orbit I assumed had ~7650m/s orbital speed), and a single burn in the direction of both the orbit around the Earth and the Earth's orbit around the Sun. It further assumed Solar escape speed was 42.1Km/s, which is true for a couple points along Earth's orbit, but I'm not sure exactly where, so I won't tell you the dates required for the burn.
If you add 9Km/s to your speed under those conditions, then you will find yourself moving along smartly in the plane of the ecliptic at just over 5250m/s relative to the Sun at some point in the indefinite future, when you are some arbitrarily large distance from the Sun (on the order of two light-months out, give or take a couple light-weeks)
"I do not agree with what you say, but I will defend to the death your right to say it"