China to land probe on the far side.

[bknight]

Interestingly, the Sun - Earth L2 point is where NASA/ESA et al  plan to place the James Webb Space Telescope when it is launched in 2018.

From the JWST Wikipedia page

"The JWST will be located near the second Lagrange point (L2) of the Earth-Sun system, which is 1,500,000 kilometers (930,000 mi) from Earth, directly opposite to the Sun. Normally an object circling the Sun farther out than Earth would take longer than one year to complete its orbit, but near the L2 point the combined gravitational pull of the Earth and the Sun allow a spacecraft to orbit the Sun in the same time it takes the Earth. The telescope will circle about the L2 point in a halo orbit, which will be inclined with respect to the ecliptic, have a radius of approximately 800,000 kilometers (500,000 mi), and take about half a year to complete. Since L2 is just an equilibrium point with no gravitational pull, a halo orbit is not an orbit in the usual sense: the spacecraft is actually in orbit around the Sun, and the halo orbit can be thought of as controlled drifting to remain in the vicinity of the L2 point. This requires some station-keeping: around 2–4 m/s per year from the total budget of 150 m/s. Two sets of thrusters comprise the observatory's propulsion system."

Good info, thanks! I just HOPE they get the mirrors and angles correct so that it works when launched.

[smartcooky]

Interestingly, the Sun - Earth L2 point is where NASA/ESA et al  plan to place the James Webb Space Telescope when it is launched in 2018.

From the JWST Wikipedia page

"The JWST will be located near the second Lagrange point (L2) of the Earth-Sun system, which is 1,500,000 kilometers (930,000 mi) from Earth, directly opposite to the Sun. Normally an object circling the Sun farther out than Earth would take longer than one year to complete its orbit, but near the L2 point the combined gravitational pull of the Earth and the Sun allow a spacecraft to orbit the Sun in the same time it takes the Earth. The telescope will circle about the L2 point in a halo orbit, which will be inclined with respect to the ecliptic, have a radius of approximately 800,000 kilometers (500,000 mi), and take about half a year to complete. Since L2 is just an equilibrium point with no gravitational pull, a halo orbit is not an orbit in the usual sense: the spacecraft is actually in orbit around the Sun, and the halo orbit can be thought of as controlled drifting to remain in the vicinity of the L2 point. This requires some station-keeping: around 2–4 m/s per year from the total budget of 150 m/s. Two sets of thrusters comprise the observatory's propulsion system."

Good info, thanks! I just HOPE they get the mirrors and angles correct so that it works when launched.

Oh, they will be testing the figure of the mirror(s), you can take that to the bank!!

Actually the HST mirror debacle was something of a two edged sword (no pun intended).  A simple test called a "Foucault" or "knife-edge" test would have revealed the spherical aberration in the mirror. Any competent amateur telescope maker would never consider putting his newly ground and coated mirror into a telescope tube without first doing this test.

However, NASA learned so much about doing actual tasks in space from the the HST repair missions, that the debacle was almost worth it. Much of what they learned from those repair and servicing missions has paid dividends in their operations on the ISS.

The JWST is going to be at L2, and therefore, there will be no way to repair it if anything goes wrong, so they had better get it right first time!!!

[Dalhousie]

China will either have to built a network similar to NASA's or rent bandwidth from them.

They have a global tracking network already on land, a fleet of tracking ships, when they need extra capacity they have rented time from from commercial stations.

[bknight]

Good info, thanks! I just HOPE they get the mirrors and angles correct so that it works when launched.

Oh, they will be testing the figure of the mirror(s), you can take that to the bank!!

Actually the HST mirror debacle was something of a two edged sword (no pun intended).  A simple test called a "Foucault" or "knife-edge" test would have revealed the spherical aberration in the mirror. Any competent amateur telescope maker would never consider putting his newly ground and coated mirror into a telescope tube without first doing this test.

However, NASA learned so much about doing actual tasks in space from the the HST repair missions, that the debacle was almost worth it. Much of what they learned from those repair and servicing missions has paid dividends in their operations on the ISS.

The JWST is going to be at L2, and therefore, there will be no way to repair it if anything goes wrong, so they had better get it right first time!!!

Amen to that.

[bknight]

China will either have to built a network similar to NASA's or rent bandwidth from them.

They have a global tracking network already on land, a fleet of tracking ships, when they need extra campacity they have rented time from from commercial stations.

Ok, didn't know that, or look it up.

[Dalhousie]

China will either have to built a network similar to NASA's or rent bandwidth from them.

They have a global tracking network already on land, a fleet of tracking ships, when they need extra campacity they have rented time from from commercial stations.

Ok, didn't know that, or look it up.

The stations include Malindi (Kenya), Karachi (Pakistan),  and Swakopmund (Namibia).

They have hired commercial tracking stations in Brazil, France, Sweden, and Dongara (Western Australia)

There are three Yuan Wang tracking ships (two in reserve), these are large, ocean-going ships of 18-24,000 tonnes.

There is a deep space tracking station under construction in Neuquen (Argentina)

There are about ten tracking stations in China also - these are spread over 75 degrees of longitude.

China also has three Tianlian tracking and data relay satellites in GEO.

Lastly they can call on a number of radio telescopes, from later this year they will include the 500 m FAST antenna.