IKAROS Flew Past Venus

[Eudoxia]

[QUOTE]

Dec. 14, 2010 | 09:22 PST | 17:22 UTC

Just after Akatsuki missed entering orbit, another spacecraft, IKAROS, quietly passed by Venus. The IKAROS blog update rate has dropped as the spacecraft has traveled farther from Earth, but they're still doing pretty regular posts on the position and spin rate of the solar sail mission. On Sunday they posted a trajectory diagram showing its path past Venus, which was bent by the planet's gravity.

[IMG]http://planetary.org/image/20101212-ikaros_venus_flyby.jpg[/IMG]
Click to enlarge >
IKAROS trajectory past Venus
IKAROS passed within 80,000 kilometers of Venus on December 8, 2010 at 07:39 UT, close enough for its trajectory to be bent. Credit: ISAS / JAXA
I think that verification of the bending of the trajectory is pretty much all the data that IKAROS will return from Venus. I know some people were hoping for images but It doesn't have a camera system capable of the sort of pointing and narrow field of view necessary to frame Venus and see anything. It's just notable that the solar sailcraft is still stable and still talking to Earth!
[/QUOTE]

Source: [url]http://planetary.org/blog/article/00002827/[/url]

[IMG]http://www.jonathanasmis.com/wp/wp-content/uploads/2010/06/solar-sail-ikaros.jpg[/IMG]

[IMG]http://www.blogcdn.com/www.engadget.com/media/2010/07/10x0713ikb235df35.jpg[/IMG]

[DainBramageStud]

I still want to know how the hell it uses a solar sail when it's flying [B]towards[/B] the sun.

[Eudoxia]

[QUOTE=DainBramageStudios;26692418]I still want to know how the hell it uses a solar sail when it's flying [B]towards[/B] the sun.[/QUOTE]

Let me draw it up for you (Because there's no other way for me to explain it).

[wuzzimu]

[QUOTE=DainBramageStudios;26692418]I still want to know how the hell it uses a solar sail when it's flying [B]towards[/B] the sun.[/QUOTE]

You know how sailboats can sail into the wind?

[DainBramageStud]

[QUOTE=wuzzimu;26692453]You know how sailboats can sail into the wind?[/QUOTE]

I know they can but I don't know how

[Eudoxia]

Here:

[IMG]http://img529.imageshack.us/img529/8061/sailhandling.png[/IMG]

EDIT: The reference is the other way around, the red is the thrust vector not the acceleration one.

[DainBramageStud]

[QUOTE=Eudoxia;26692647]Here:

[img_thumb]http://img529.imageshack.us/img529/8061/sailhandling.png[/img_thumb]

EDIT: The reference is the other way around, the red is the thrust vector not the acceleration one.[/QUOTE]

still sort of confused

if the thing is flying into the sun then I don't see how the rays can get behind it like in the first two pictures

[Eudoxia]

[QUOTE=DainBramageStudios;26693110]still sort of confused

if the thing is flying into the sun then I don't see how the rays can get behind it like in the first two pictures[/QUOTE]

It's vertical, the upper-left corresponds with the bottom-left frame, upper-right with lower-right.

It means that if you angle the sail so the normal line (The line perpendicular to the sail's plane) points forward (Remember that the sail is orbiting the Sun, so forward is the direction of motion) then you move ahead, if you point it backward (Like a parachute) the thrust points in the other direction, so the reduction of orbital momentum causes the sail to spiral inwards,

[_Kayla_]

I'm loving all of the space news recently, hope that all this gets put into practice for manned spaceflight.

[petieng]

[QUOTE=DainBramageStudios;26692418]I still want to know how the hell it uses a solar sail when it's flying [B]towards[/B] the sun.[/QUOTE]

You have to remember that when spacecraft fly between two points, it will very rarely in a straight line. You don't just point yourself at Venus and apply thrust. Due to orbital mechanics, a lot of the time you need to apply thrust perpendicular to where you want to go.
For the craft to get to Venus it actually has to lose some of its velocity, allowing it to fall into a lower orbit. You can angle the sail, like Eudoxia has shown in the diagram to deflect the Sun's light in the same direction the Earth is orbiting. This imparts a force opposite to the Earth's orbit, slowing the craft down and allowing it to fall towards the Sun.

Sitting firmly in a chair on Earth's surface, you don't feel like you're moving at all, but relative to the Sun you're travelling at a good 67,000mph. You have to shed off some of that speed if you want to fall towards the Sun. Eudoxia's parachute analogy is a really good one in this case.

[Jimjim32]

It's a good diagram to explain the motion, but yeah, essential what he said, by slowing the velocity of the sail relative to its orbit, it drop into a lower orbit to remain stable.