On January 15, 1998, NASA announced a return to orbit for John Glenn, 76, the first American to orbit the Earth who at the time was serving as a U.S. Senator from Ohio.

Senator Glenn asked NASA if he could fly again to conduct space-based research on aging, but only if he met the agency's physical and mental requirements. NASA Administrator Dan Goldin announced the appointment of John Glenn as a member of the crew of the Space Shuttle Discovery for mission STS-95, scheduled for October 29, 1998.

At 77 years of age, Glenn was the oldest astronaut to fly in space, nearly twice the age of the average astronaut. The highly successful mission concluded with the landing on Saturday, November 7, 1998 at 12:04 PM EST at KSC.

Read more about this remarkable man, John Glenn.

Learn what else happened this date in history.

Image Credits: NASA

Born October 29, 1656 in Haggerston, Shoreditch, England, Edmund Halley was an assistant to John Flamsteed, Astronomer Royal, assisting with observations at Oxford and Greenwich. When Flamsteed published his findings in "Philosophical Transactions of the Royal Society" in 1675, he mentioned Halley by name.

After publishing his catalogue of southern hemisphere stars, Halley was elected a member of the Royal Society. At the age of 22, he was among the youngest members.

Edmund Halley died on this date in 1742 in Greenwich, England. He did not survive to see the return of the comet, which would later bear his name, on Christmas day in 1758. His "Tabulae astronomicae" was published 7 years after his death.

Read more about Edmund Halley.

Image Credits: Public Domain

At NASA's Kennedy Space Center in Florida, space shuttle Discovery completed its journey from Orbiter Processing Facility-3 to the Vehicle Assembly Building, or VAB, 3:30 PM EST Wednesday. An earlier rollover was delayed to allow technicians to replace a tire with low pressure and wait out a midday rainstorm.

The shuttle was fitted with a hoisting device and lifted vertically by a heavy-duty crane late Wednesday night and now is being lowered onto the mobile launcher platform. It will be joined early this afternoon with the solid rocket boosters and external fuel tank already inside the building's high bay.

NASA's crawler-transporter will be rolled under the shuttle stack for the trip to Kennedy's Launch Pad 39A, scheduled for 4 AM Jan. 14 -- the next major milestone of the STS-119 mission.

The payload, consisting of the S6 truss segment and the final set of U.S. solar arrays, will be transported to the pad Jan. 11, just prior to the shuttle's arrival.

Commander Lee Archambault will lead a crew of seven, along with Pilot Tony Antonelli, and Mission Specialists Joseph Acaba, John Phillips, Steve Swanson, Richard Arnold and Japan Aerospace Exploration Agency astronaut Koichi Wakata.

The astronauts are expected to be at Kennedy for a full-dress rehearsal, called the Terminal Countdown Demonstration Test, Jan. 19-21. They will have the opportunity to check out the spacecraft and payload, try on their custom-made flight suits and review safety procedures.

Discovery's STS-119 mission to the International Space Station is targeted for lift off 7:32 AM EST, Feb. 12.

Image Credit: NASA/Jim Grossmann

Honey, I blew up the galaxy.

Well, not exactly. It appears that the Milky Way Galaxy has always been larger than we originally thought. We're also moving faster and unfortunately more likely to collide with another galaxy as well.

Astronomers making high-precision measurements using the National Science Foundation’s Very Long Baseline Array (VLBA) radio telescope to remake the map of the Milky Way say our solar system is about 28,000 light-years from the Milky Way’s center. At that distance, the new observations indicate, we’re moving at about 600,000 miles per hour in our Galactic orbit, up from the previous estimate of 500,000 miles per hour.

That increase in speed, said Mark Reid of the Harvard-Smithsonian Center for Astrophysics, increases the Milky Way's mass by 50 percent, bringing it even with the Andromeda Galaxy. "No longer will we think of the Milky Way as the little sister of the Andromeda Galaxy in our Local Group family."

The larger mass, in turn, means a greater gravitational pull that increases the likelihood of collisions with the Andromeda galaxy or smaller nearby galaxies.

Taking advantage of the VLBA’s unparalleled ability to make extremely detailed images, the team is conducting a long-term program to measure distances and motions in our Galaxy. They reported their results at the American Astronomical Society’s meeting in Long Beach, California.

The VLBA can fix positions in the sky so accurately that the actual motion of the objects can be detected as they orbit the Milky Way’s center. Adding in measurements of motion along the line of sight, determined from shifts in the frequency of the masers’ radio emission, the astronomers are able to determine the full 3-dimensional motions of the star-forming regions. Using this information, Reid reported that “most star-forming regions do not follow a circular path as they orbit the Galaxy; instead we find them moving more slowly than other regions and on elliptical, not circular, orbits.”

“The new VLBA observations of the Milky Way are producing highly-accurate direct measurements of distances and motions,” said Karl Menten of the Max Planck Institute for Radio Astronomy in Germany, a member of the team. “These measurements use the traditional surveyor’s method of triangulation and do not depend on any assumptions based on other properties, such as brightness, unlike earlier studies.”

The astronomers found that their direct distance measurements differed from earlier, indirect measurements, sometimes by as much as a factor of two. The star-forming regions harboring the cosmic masers “define the spiral arms of the Galaxy,” Reid explained. Measuring the distances to these regions thus provides a yardstick for mapping the Galaxy’s spiral structure.

“These direct measurements are revising our understanding of the structure and motions of our Galaxy,” Menten said. "Because we’re inside it, it’s difficult for us to determine the Milky Way’s structure. For other galaxies, we can simply look at them and see their structure, but we can’t do this to get an overall image of the Milky Way. We have to deduce its structure by measuring and mapping,” he added.

Reid and his colleagues found other surprises, too. Measuring the distances to multiple regions in a single spiral arm allowed them to calculate the angle of the arm. “These measurements,” Reid said, “indicate that our Galaxy probably has four, not two, spiral arms of gas and dust that are forming stars.” Recent surveys by NASA’s Spitzer Space Telescope suggest that older stars reside mostly in two spiral arms, raising a question of why the older stars don't appear in all the arms. Answering that question, the astronomers say, will require more measurements and a deeper understanding of how the Galaxy works.

Image Credits: Robert Hurt, IPAC; Mark Reid, CfA, NRAO/AUI/NSF