Solar Probe Plus to launch in 2018: Top speed will be .067% Light speed

[Stormbringer]

http://blogs.scientificamerican.com/life-unbounded/2013/02/25/the-fastest-spacecraft-ever/

In 2018 though, a new NASA mission – Solar Probe Plus – will be launched. Designed to come as close as 8.5 solar radii to the Sun (that’s about about 5.9 million kilometers or 3.7 million miles), it will hit orbital velocities as high as 200 kilometers a second (450,000 miles an hour).

To just put that incredible figure into perspective – going this fast would get you from the Earth to the Moon in about 1/2 an hour. It is also about 0.067% the speed of light.

More about Solar Probe Plus:

http://solarprobe.jhuapl.edu/

The First Mission to the Nearest Star
Solar Probe Plus will be a historic mission, flying into the Sun's atmosphere (or corona) for the first time. Coming closer to the Sun than any previous spacecraft, Solar Probe Plus will employ a combination of in situ measurements and imaging to achieve the mission's primary scientific goal: to understand how the Sun's corona is heated and how the solar wind is accelerated. Solar Probe Plus will revolutionize our knowledge of the origin and evolution of the solar wind.

the probe will actually dive into the sun's "atmosphere." amazing stuff. But you know that speed...
just a couple of decimal places to go. we're getting there!

[Stormbringer]

last year a comet took a similar dive through the sun's atmosphere and before it happened there was speculation about whether it would survive the pass or be destroyed. i think it was destroyed. but it was a natural clump of ice and rock and dirt and not something engineered specifically to survive such a near solar pass.

what if we engineered an interstellar probe to survive as near a pass as is materially possible to get that incredible speed boost? a probe that also had the best propulsion we can manage at the moment. What would we get in terms of final velocity? could we get to i percent C? more? .067 seems pretty close to 1 percent c. over 2/3's of the way with only .33 percent to go.

[Giovanni DS]

You are missing a zero, it is 0.067 not 0.67

[Stormbringer]

You are missing a zero, it is 0.067 not 0.67

I don't think so. i included the zero after the decimal place and assumed that the blogger was talking about .67 percent of 1 percent c. but even if i did drop a zero the corrected percent is still an incredible leap over previous records.

[Stormbringer]

If the blogger got his decimals right that means a 433 year probe to Alpha Centauri is within the realm of reason.

Even if he got the decimal wrong and it is 4330 years that is still a lot better than the current contender of about  70,000 years to get there.

Edit: if he was off by two decimal places then the figures are 4330 and 43300. nasty but still better than 70K.

[rklaehn]

last year a comet took a similar dive through the sun's atmosphere and before it happened there was speculation about whether it would survive the pass or be destroyed. i think it was destroyed. but it was a natural clump of ice and rock and dirt and not something engineered specifically to survive such a near solar pass.

what if we engineered an interstellar probe to survive as near a pass as is materially possible to get that incredible speed boost? a probe that also had the best propulsion we can manage at the moment. What would we get in terms of final velocity? could we get to i percent C? more? .067 seems pretty close to 1 percent c. over 2/3's of the way with only .33 percent to go.

You don't get the speed for free. You lose it again when you get out of the suns gravity well.

However, the delta-v of a maneuver at perihelion with a realistic delta-v (10km/s) would be multiplied by the oberth effect. A hyperbolic excess velocity (velocity at r=infinity) of 100km/s seems within reach.

That won't get you anywhere near the next star in a reasonable time, but it could get you to e.g. the gravitational focal point of the sun at 500au for a gravity lens telescope in less than two decades.

Edit: if you want to play around with this, this is what you will need:

Solar G*M = 132,712,440,018,000,000,000
Solar R = 695,800,000
Local escape velocity v_e = Sqrt(2*G*M/R)
Oberth Boost: Sqrt((v_e+delta_v)^2-v_e^2)

So let's assume that you can get to 4 solar radii (3 solar radii above the surface, which is what the original solar probe wanted to do http://solarprobe.gsfc.nasa.gov/sp_mccomas_cospar04.pdf). Then your velocity will be about

sqrt(2*132712440018000000000/(4*695800000)) = 308815 m/s

If you do a burn with a delta-v of 10000m/s exactly at perihelion, you get a hyperbolic excess velocity of

sqrt((308815+10000)^2-308815^2) = 79223 m/s.

That gets you to the beginning of the "solar focal distance" of 550AU in about 30 years.

[Stormbringer]

You don't get the speed for free. You lose it again when you get out of the suns gravity well.

However, the delta-v of a maneuver at perihelion with a realistic delta-v (10km/s) would be multiplied by the oberth effect. A hyperbolic excess velocity (velocity at r=infinity) of 100km/s seems within reach.

That won't get you anywhere near the next star in a reasonable time, but it could get you to e.g. the gravitational focal point of the sun at 500au for a gravity lens telescope in less than two decades.

yeah i figured you lose a lot of the speed if you tried to leave the vicinity of the sun. still the speed is an impressive accomplishment for a conventional drive. even though it's cheating; a man made speed of nearly 1 percent C is kind of notice that we can do it.

With regard to the 500AU telescope that too is a worthy goal and one i support. Plus; you need a receiver for any interstellar probe in order for it to do any good and the effect of lensing you are taking advantage of for the telescope also applies to radio signals from a far distant transmitter. in short we need a receiver at one of the sun's lensing points. taking advantage of lensing the probe transmitter and power supply requirements are greatly reduced which shrinks the mass needed for the probe.

[KelvinZero]

http://blogs.scientificamerican.com/life-unbounded/2013/02/25/the-fastest-spacecraft-ever/

In 2018 though, a new NASA mission – Solar Probe Plus – will be launched. Designed to come as close as 8.5 solar radii to the Sun (that’s about about 5.9 million kilometers or 3.7 million miles), it will hit orbital velocities as high as 200 kilometers a second (450,000 miles an hour).

To just put that incredible figure into perspective – going this fast would get you from the Earth to the Moon in about 1/2 an hour. It is also about 0.067% the speed of light.

I think it has been said, but this is a bit less than a thousandth of the speed of light, which is about 300,000 km/s

Nothing to sneeze at! The radius of the galaxy is around 100,000 light years, so a thousandth of the speed of light is fast enough to colonize it in 100 million years, ie if any race had achieved this velocity it would have been enough to colonize the galaxy several times over by now. This is an example of the Fermi "paradox".

I think it is incredible if these speeds are already within our reach. So what is the escape velocity starting from ten radiuses from the sun? How much velocity is lost?

(if the answer is pretty much all of it, that is also interesting in that it implies that a delta-v point of view, the truely inner solar system is as hard to visit as interstellar objects)

[Stormbringer]

i am not sure because i am not well versed in the mathematics and mechanics of it. i think you'd lose a lot of the velocity gained though. if not i wonder what a few preliminary gravity assists at the jovian worlds would do before heading for the near sun pass?

also... lets fix this decimal place issue. i think the article means more like .0067 c. is that right? or is it worse: .00067?

under my assumption that the article means.0067 it is in the thousandths of a percent range but well towards the hundredths column. am i wrong?

if its what i think it is it's sure a lot closer to actual useful speeds for early interstellar missions than the forth decimal column.

never the less:  voyager and Helios are in the 5th decimal place if i recall correctly. so even a 4rth decimal place value for this thing is an order of magnitude better. at least that's something.

[ncb1397]

There isn't really a decimal point issue or there shouldn't be...

1% c = .01 c
.067% c = .00067 c

[EE Scott]

Have they assigned a launch vehicle for this mission yet?

[Tomness]

Too bad it cant go + .5 past light speed 

[Orbiter]

Have they assigned a launch vehicle for this mission yet?

Either FH or Delta IV Heavy, apparently.

[aero]

In case anyone is still in doubt, the speed of light in free space is defined to be a number slightly smaller than 300,000 km/s.
100% c =300,000 km/s, the speed of light in free space.
10% c = 30,000 km/s
1 % c = 3,000 km/s
0.1 % c = 300 km/s
0.01 % c = 30 km/s = 30,000 m/s, exhaust velocity of some ion engine.
0.001 % c = 3 km/s = 3,000 m/s which is in the ball park of exhaust velocity of chemical rockets.
0.0001% c = 0.3 km/s = 300 m/s. I'm sure there is a bullet that travels at that speed.

[rklaehn]

i am not sure because i am not well versed in the mathematics and mechanics of it. i think you'd lose a lot of the velocity gained though.

You will use all of the velocity gained. The only way to benefit from being so fast is to perform an impulsive manoeuvre and benefit from the oberth effect.

If not i wonder what a few preliminary gravity assists at the jovian worlds would do before heading for the near sun pass?

A jovian flyby is one of the cheapest ways to get close to the sun. The original solar probe was going to use a jovian flyby to get to within 4 solar radii. The newer solar probe plus (which relies on solar power instead of an RTG) does multiple venus flybys, and does not get as close. For a spacecraft that is expected to go into interstellar space you would need an RTG anyway, so doing a jupiter flyby would be the obvious choice.

An interesting way to do a large quasi-impulsive manoeuvre close to the sun would be solar thermal propulsion using liquid hydrogen. The liquid hydrogen could produce an Isp of 900s and also be used to cool the spacecraft when close to the sun.

[Stormbringer]

In case anyone is still in doubt, the speed of light in free space is defined to be a number slightly smaller than 300,000 km/s.
100% c =300,000 km/s, the speed of light in free space.
10% c = 30,000 km/s
1 % c = 3,000 km/s
0.1 % c = 300 km/s
0.01 % c = 30 km/s = 30,000 m/s, exhaust velocity of some ion engine.
0.001 % c = 3 km/s = 3,000 m/s which is in the ball park of exhaust velocity of chemical rockets.
0.0001% c = 0.3 km/s = 300 m/s. I'm sure there is a bullet that travels at that speed.

so this probe will hit a high speed of about 200 KM/s according to the cite i quoted. so we are all right i think. it falls in at 2/3 of the way to the forth entry in your table. whatever percent it is its faster by about 6 times than voyager. it has taken 36 years for voyager to get 17 light hours away from earth. it would take this probe 6 years to pass voyager were it not for velocity penalties due to gravity involved with an intercept course as opposed to it's original course.

[aceshigh]

yes, Voyager's speed is just 17 km per second.

[Proponent]

Have they assigned a launch vehicle for this mission yet?

Either FH or Delta IV Heavy, apparently.

Likely.  It was going to be Atlas V, but that would have required development of a new kick stage.  Project management decided this entailed too much risk:

Solar Probe Plus, NASA’s ‘Mission to the Fires of Hell,’ Trading Atlas 5 for Bigger Launch Vehicle

[Vultur]

Yeah, this is fast, but not really in a way that's useful for interstellar travel.

(Btw, wasn't there another Alpha Centauri thread on here yesterday?)

[Stormbringer]

Yeah, this is fast, but not really in a way that's useful for interstellar travel.

(Btw, wasn't there another Alpha Centauri thread on here yesterday?)

I believe the mods killed it because it turned a little nasty. besides this is not about alpha centauri It's about the need...The need for speed!