Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2004 September 1 
Posted on 09/01/2004 9:34:45 AM PDT by petuniasevan
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2004 September 1
Explanation: Is our Solar System unique? The discovery of a Neptune-mass planet in an sub-Mercury orbit around nearby Sun-like star 55 Cancri, announced yesterday along with the discovery of other similar systems, gives a new indication that planetary systems as complex as our own Solar System likely exist elsewhere. The planet, discovered in data from the Hobby-Eberly telescope in Texas, the Lick Observatory in California, and the orbiting Hubble Space Telescope, is one of four planets now known to orbit 55 Cancri -- the others being similar in mass to Jupiter. The finding involved noting subtle changes in the speed of the star caused by its orbiting planets. The above drawing depicts what this planet might look like, assuming a mass similar to Neptune, but a composition similar to Earth. The star 55 Cancri, only 40 light-years distant, is visible with binoculars towards the constellation of Cancer.
Lockheed Martin's Atlas 2 family of boosters rocketed into retirement Tuesday, placing a classified U.S. national security satellite into space following a sunset sendoff from Cape Canaveral.
Riding 685,000 pounds of thrust from the liquid-fueled MA-5A main engine package and solid-propellant strap-on boosters, the 156-foot tall Atlas 2AS roared away from pad 36A at 7:17 p.m. EDT (2317 GMT).
 The final Atlas 2AS rocket lifts off. Credit: International Launch Services |
Virtually every Atlas from the Cape heads eastward to deliver satellites into equatorial orbits around the planet. But this mission was different, taking a northeasterly track that paralleled the U.S. eastern seaboard. The reason: Atop the rocket was a secret payload headed into a highly inclined, highly elliptical orbit, sometimes called a Molynia-style orbit.
Most space experts agree the rocket deployed a data relay satellite that will be used to route information from polar-orbiting photo reconnaissance spacecraft to ground receivers.
Early versions of these relay craft were launched starting in the mid-1970s, followed by a second-generation of satellites that were carried aloft on space shuttle missions in 1989 and 1992 and a Titan 4 rocket in 1996.
Tuesday's launch is believed to have been the second time an Atlas 2 rocket launched such a craft toward a Molynia-style orbit. A mission in early 1998 followed a similar northeast trajectory.
Military watchers suspect the data relay satellites have operated under the codename Quasar.
It is believed the government has two relay satellite constellations -- one flying in highly elliptical orbits and the other parked in geostationary orbit around the planet's equator.
The geostationary satellites probably take the place of the military relay mission previously handled by NASA's Tracking and Data Relay Satellite System. They probably relay information both from radar imaging satellites in low Earth orbit as well as signals intelligence satellites in geosynchronous orbit, creating a switchboard in the sky.
The secretive National Reconnaissance Office, the government agency responsible for the U.S. fleet of spy satellites, would not disclose any information about the craft launched Tuesday.
 As seen from the Cape Canaveral press site, the Lockheed Martin Atlas 2AS vehicle launches just before sunset. Credit: Steven Young/Spaceflight Now |
Tuesday's launch was a bittersweet moment for Atlas workers. As the solid boosters and first stage fired and dropped away during the first five minutes of flight, each jettison marked the closing of a chapter in Atlas history.
The ATK Thiokol-made solid motors were used for the last time after 30 missions in the past 11 years; and Rocketdyne-powered Atlas first stages had flown 576 times dating back to the program's inception in the 1950s.
But the Atlas program is transitioning entirely to its next-generation vehicle -- the Atlas 5. Powered by the Russian-designed RD-180 main engine and Aerojet-made solid boosters, the Atlas 5 was conceived by Lockheed Martin to be a series of rockets with different configurations to carry a wide range of payloads into space while being cheaper and easier to operate than heritage systems.
The Atlas 2 family completed its service life Tuesday the same way it began by achieving a successful outcome. Since December 1991, 63 launches of Atlas 2, 2A and 2AS-model vehicles have lofted satellites for commercial customers, the U.S. military and NASA with a flawless record.
"This is an awesome accomplishment, being the only U.S. expendable launch vehicle series to have had 100 percent success throughout its entire lifespan," said Mark Albrecht, president of the Atlas marketing firm International Launch Services. "The Atlas team is an incredible group of people who make mission success for our customers a way of life."
 The Atlas rocket soared into clear skies as seen from the Jetty Park pier. Credit: Judy Ray/Spaceflight Now |
"It has been an incredible workhorse for the Atlas program, but it also served as a stepping stone into Atlas 5 for the evolution of the vehicle," launch director Adrian Laffitte added.
As the Atlas 2 series continued to fly, the program looked to build more powerful rockets to accommodate larger spacecraft being ordered. That led to Atlas 3, which built upon proven systems of Atlas 2 while incorporating the new Russian RD-180 powerplant.
The Atlas 3 has launched five times to date, successfully serving as a transition rocket from Atlas 2's reliable legacy to the next-generation Atlas 5, which has completed three missions.
Next up on the launch schedule is a commercial communications satellite deployment mission in early December using an Atlas 5. That will be followed in mid-January by the sixth and final Atlas 3 flight. It will carry another NRO payload.
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25 years ago the Atlas was done, finished, zero interest. Except for a small group of true believers. I asked them how much it would cost me to build an Atlas plant here and they took it seriously, $2 billion. I began to get the project in gear and then the price of copper dropped below $1, so that was the end of that. They obviously continued on and began to make some sales of the Atlas and here they are today with one of the hottest rockets on earth.
Awesome picture of the day! My favorite site. Thanks for posting all the information about the Atlas 2. 8^)
Thank you.
Sweet. Thank you.
| Planet | Period | Tperi (JD-2450000) | ecc | omega (deg) | Vel Amp, K (m/s) | M sin i (Mjup) | a (AU) |
|---|---|---|---|---|---|---|---|
| b | 14.653 d | 1.479 | .02 | 99 | 72.2 | 0.84 | 0.115 |
| c | 44.28 d | 31.4 | .34 | 61 | 13.0 | 0.21 | 0.24 |
| d | 5360 d | 2785 | .16 | 201 | 49.3 | 4.05 | 5.9 |
The inner planet was announced by Butler et al. in January 1997. Analysis of extended velocity measurements reveals additional velocity variations.
The innermost planet of 55 Cancri is a mere 10 million miles off the face of the Sun. Since satellites in prograde rotation experience a transfer of momentum from the parent body, it must have been captured, or spit out of the star; either way, it hasn't been in orbit for long. :')
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