6+ years to Mercury
Aug. 3rd, 2004 09:31 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
mmcirvinMESSENGER takes off for Mercury.
It won't enter orbit until 2011 (though it will encounter Mercury three times before then). The reason is that, while it's nearby in solar-system terms, in another sense Mercury is as hard to get to as Pluto. It will take all that time for the probe to lose enough energy in a series of planetary encounters. Mercury travels much faster than Earth around the Sun, but it's also far downhill in the Sun's gravity well; if it fell in on the simplest elliptical orbit from Earth, MESSENGER would be traveling even faster than Mercury by the time it got there, and it would be impossible for it to match velocities in order to enter orbit.
There exist good maps only of half of Mercury, photographed by Mariner 10 in two brief encounters thirty years ago.
It won't enter orbit until 2011 (though it will encounter Mercury three times before then). The reason is that, while it's nearby in solar-system terms, in another sense Mercury is as hard to get to as Pluto. It will take all that time for the probe to lose enough energy in a series of planetary encounters. Mercury travels much faster than Earth around the Sun, but it's also far downhill in the Sun's gravity well; if it fell in on the simplest elliptical orbit from Earth, MESSENGER would be traveling even faster than Mercury by the time it got there, and it would be impossible for it to match velocities in order to enter orbit.
There exist good maps only of half of Mercury, photographed by Mariner 10 in two brief encounters thirty years ago.