Chandra Captures Venus In A Whole New Light

Wouter wrote in to tell us about new X-Ray pics of Venus. Scientists belive this will enable them to get a better feel for character of the planets opaque atmosphere.

Re:I dunno...

[imrdkl]

Check the article again:

Venus looks brightest at the limb

Limbs

[itwerx]

Do those look like arms to you?!?
('Course they don't look like her legs either... :)

A technological triumph?

[imrdkl]

Can someone explain the bit from the article about how venus could never be properly tracked before this? I never knew that satellites use stars to track planets, but I guess it makes sense. What made it work this time with no tracking star?

Re:A technological triumph?

[teridon]

Satellites don't directly use stars to track planets. The star tracker is used to track stars. If you know which star(s) you are tracking, you know how the spacecraft is pointed.

The reason other spacecraft could not track Venus before is that Venus is so close (angularly) to the Sun (the angular seperation never exceeds 48 degrees). Most telescopes are not designed to withstand that kind of brightness or radiation.

Excerpt from http://chandra.harvard.edu/about/spacecraft.html:
The sunshade door is one of the most basic and important elements of the spacecraft system. This sunshade door remained closed until Chandra achieved pointing control in orbit. Now that it is opened, it shadows the entrance of the telescope to allow it to point as close as 45 degrees to the sun.

Looks like a safety margin of three degrees! Also, when you point a spacecraft at or nearly at the sun, you may be heating the spacecraft in places it was not designed for. This can be especially bad for some optics, especially if they are thermally controlled.

Other spacecraft, like SOHO [nasa.gov] are designed to point at the sun.

Disclaimer: I work on SOHO

You know you get too much SPAM ...

[Lars T.]

when you read the above as "See X-rated pictures of Venus Williams here".