Here is the stack rank of operating missions as of 2008 (when NASA needed to shut down some missions to save money):
1. Swift, 2004
2. Chandra, 1999
3. Galex (Galaxy Evolution Explorer, ultraviolet), 2003
4. Suzaku (X-ray), 2005
5. Spitzer, 2003
6. WMAP (Wilkinson Microwave Anisotropy Probe), 2001
7. XMM-Newton (X-ray Multi-Mirror Mission), 1999
8. Integral (INTErnational Gamma-Ray Astrophysics Laboratory), 2002
9. Rossi X-ray Timing Explorer, 1995
10. Gravity Probe B, 2004
source: http://www.newscientist.com/article/dn13938?DCMP=ILC-hmts...
I also found this read (http://www.skyandtelescope.com/news/121390204.html) very interesting.
Here is the stack rank of operating missions as of 2008 (when NASA needed to shut down some missions to save money):
1. Swift, 2004
2. Chandra, 1999
3. Galex (Galaxy Evolution Explorer, ultraviolet), 2003
4. Suzaku (X-ray), 2005
5. Spitzer, 2003
6. WMAP (Wilkinson Microwave Anisotropy Probe), 2001
7. XMM-Newton (X-ray Multi-Mirror Mission), 1999
8. Integral (INTErnational Gamma-Ray Astrophysics Laboratory), 2002
9. Rossi X-ray Timing Explorer, 1995
10. Gravity Probe B, 2004
source: http://www.newscientist.com/article/dn13938?DCMP=ILC-hmts...
I also found this read (http://www.skyandtelescope.com/news/121390204.html) very interesting.