The Johns Hopkins Gazette: August 3, 1998
August 3, 1998
VOL. 27, NO. 41


NEAR Mission, So Far

Space: APL prepares for the final stage of its maiden interplanetary mission

Greg Rienzi
The Gazette

Johns Hopkins Gazette Online Edition

Somewhere far out in our solar system, the NEAR spacecraft, developed, designed and built at the Applied Physics Laboratory, has been hurtling at a speed of 10 kilometers per second toward an asteroid that is roughly twice the size of Manhattan.

But movie fans and those caught up in the threat of an asteroid impact eradicating all life on Earth need not worry. Unless you plan on living 1.5 million years, the earliest possible date the asteroid will come near the planet, this particular space rock isn't worth losing any sleep over.

Eros, as the object is called, is what astronomers call a near-Earth asteroid. It was discovered nearly 100 years ago, and mankind will have its first up-close-and-personal look at this planetary body in just five months, when the NEAR spacecraft, whose acronym stands for Near Earth Asteroid Rendezvous, will begin to orbit and study the asteroid.

Yet beyond the spacecraft's construction, this mission is particularly significant to APL scientists because it's the first interplanetary mission that is being controlled from the campus. Since the spacecraft was launched on Feb. 17, 1996, from Kennedy Space Center in Florida, a small room at APL, no bigger than an average classroom, has served as the operations center for the NEAR mission.

For NEAR team members, the realization that the spacecraft's three-year journey to Eros will be over in January is just now sinking in. "Now it's crunch time," says Carolyn Chura, a mission flight controller.

Carolyn Chura is part of a 12-member team that monitors the NEAR interplanetary mission from the operations center at APL. Chura, a flight controller, checks the status of her spacecraft at a computer terminal nicknamed "The three-headed monster."

"It's getting exciting. This should be interesting," says Chura, as she sits at a terminal she refers to as the three-headed monster: a central processing unit connected to three monitors that display data being sent back from the spacecraft.

Chura is one of a 12-member team in the operations center that puts in around 40 hours per week to make sure that the spacecraft is healthy and that the mission is proceeding as planned. For most members of the team, this is their first interplanetary mission, and according to Mark Holdridge, NEAR mission operations manager, it's been a learning experience for everybody.

Holdridge says that the added difficulties of interplanetary missions are the time delay for instructions to reach the spacecraft and the smaller margin for error. For example, to send an instruction to the spacecraft, the data must be sent through the mainframe at APL, then to NASA's Goddard Space Flight Center in Greenbelt, Md., and then to the Jet Propulsion Lab in Pasadena, Calif., before it goes out to the worldwide Deep Space Network. The Deep Space Network communicates with spacecraft from its complexes in the Mojave Desert near Goldstone, Calif.; near Madrid, Spain; and near Canberra, Australia. In total, it's roughly a 10-minute round trip for the signal to go to the spacecraft and be acknowledged back at APL.

"When we deal with these kinds of delays in January, we'll only get one chance," Holdridge says, "We'll realize it can be an intense, short-lived operation."

Holdridge says the team dealt with this small window of error last year, when the spacecraft did a fly-by of the asteroid Mathilde in order to take some photos.

But the process then was--as it will be Dec. 20, when the spacecraft will begin a series of rendezvous maneuvers with the asteroid over a four-week period--to proceed slowly and methodically and test every instruction in a simulator before the actual message is sent out into space.

"It's my job to eliminate the excitement and unplanned activities. Even though that's not always the case," Holdridge says.

The NEAR mission to Eros was planned by APL engineer Robert Farquhar, a former NASA employee, who came to APL in 1990. Farquhar, the veteran of many space missions, including Apollo 17, is well-known as the flight director for the International Cometary Explorer, the first spacecraft to visit a comet.

APL scientist Robert Farquhar planned the NEAR mission to asteroid Eros, marking the first time a spacecraft will orbit a small body. The project, which began three years ago, is the first interplanetary mission being controlled from the APL campus. Though he has worked on big-budget projects like Apollo 17, Farquhar insists he prefers the small-body missions.

The NEAR mission is the first in NASA's Discovery Program, a series of relatively low-cost interplanetary missions that have short development and flight times. The NEAR development cost of $118 million, $4 million under budget, was funded through NASA. The amount includes the cost of constructing the spacecraft, its launch and 30 days of operation time, but not the cost of the launch vehicle.

Farquhar insists that he prefers these low-budget endeavors to long-term costly missions such as Mars exploration.

"I like the small-body missions. There are a lot of missions going to Mars, and they're getting down to second- and third-level details of what is going on there. I start to lose interest," says Farquhar, mission manager for the NEAR project. "I like to get the first picture of something."

These indeed will be the first pictures taken of Eros. But the mission also will be the first time in history a spacecraft will orbit a small body and the first in-depth exploration of a near-Earth asteroid.

"These are major firsts. It will give APL a lot of credibility in its efforts to develop other space missions," says Farquhar, who has an asteroid named after him, number 5256, now the last four digits of his phone number. "It's an exciting time."

In December, as the spacecraft nears Eros, the operations center team will increase from 12 to roughly 20 and will be manned 24 hours a day. On Jan. 10, not coincidentally the anniversary of Farquhar's marriage, the spacecraft will begin its orbit of the asteroid and start its 13-month examination of the asteroid's physical shape, mineralogy, density, elemental composition and magnetic field. During the last two months of the mission, it will spiral down to an orbit of 1 kilometer off its surface.

But as to what surprises the asteroid might hold, Farquhar says, probably not too many.

But, he says with a smile, you never know. "Maybe we'll find a black monolith such as Arthur C. Clarke envisioned in 2001."