[ExI] gravity glitches

[Damien Broderick]

<http://www.space.com/scienceastronomy/080229-spacecraft-anomaly.html>

sample:

<The researchers looked at six deep-space probes 
­ Galileo I and II to Jupiter, the NEAR mission 
to the asteroid Eros, the Rosetta probe to a 
comet, Cassini to Saturn, and the MESSENGER craft 
to Mercury. Each spacecraft flew past the our 
planet to either gain or lose orbital energy in 
their quests to reach their eventual targets.

In five of the six flybys, the scientists have confirmed anomalies.

"I am feeling both humble and perplexed by this," 
said Anderson, who is now working as a retiree. 
"There is something very strange going on with 
spacecraft motions. We have no convincing 
explanation for either the Pioneer anomaly or the flyby anomaly."

In the one probe the researchers did not confirm 
a noticeable anomaly with, MESSENGER, the 
spacecraft approached the Earth at about latitude 
31 degrees north and receded from the Earth at 
about latitude 32 degrees south. "This 
near-perfect symmetry about the equator seemed to 
result in a very small velocity change, in 
contrast to the five other flybys," Anderson 
explained ­ so small no anomaly could be confirmed.

The five other flybys involved flights whose 
incoming and outgoing trajectories were 
asymmetrical with each other in terms of their 
orientation with Earth's equator.

For instance, the NEAR mission approached Earth 
at about latitude 20 south and receded from the 
planet at about latitude 72 south. The spacecraft 
then seemed to fly 13 millimeters per second 
faster than expected. While this is just 
one-millionth of that probe's total velocity, the 
precision of the velocity measurements was 0.1 
millimeters per second, carried out as they were 
using radio waves bounced off the craft. This 
suggests the anomaly seen is real ­ and one needing an explanation.

The fact this effect seems most evident with 
flybys most asymmetrical with respect to Earth's 
equator "suggests that the anomaly is related to 
Earth's rotation," Anderson said. >