Data is being received from NASAs Near Earth Asteroid Rendezvous (NEAR) Shoemaker spacecraft sitting on the dusty surface of Asteroid 433 Eros.
NEAR Shoemakers gamma ray spectrometer was commanded by ground controllers to turn itself on Feb. 15. The instrument dutifully began collecting science data about Eros.
Information gleaned by the device was received by NEAR scientists and engineers on Sunday, Feb. 18.
"Its working and we got reasonably good looking spectra...the spectra we have received looks very good," Jacob Trombka, NEAR team leader for the X-ray Gamma Ray Spectrometer at NASAs Goddard Space Flight Center in Greenbelt, Maryland, told SPACE.com.
The gamma ray spectrometer appears to be running at higher temperatures than in the past. This is due, apparently, to the spacecrafts new location on the asteroid, rather than orbiting above the giant space rock.
"When were up in orbit we can radiate the heat. On the surface, you cant radiate all the thermal heat due to the power were using for transmitting and operating. If we could arrange an atmosphere on Eros, then we could get some convection. But I think that costs too much," Trombka said with a laugh.
On track
Precious time is being found on the heavily used Deep Space Network (DSN) of radio dishes to make contact with NEAR Shoemaker, said Robert Farquhar, NEAR mission director at The Johns Hopkins University Applied Physics Laboratory (APL). On Monday, as well as Thursday of this week, additional "tracks" of time on the DSN will allow for more data to be gleaned from the gamma ray spectrometer, he said.
The DSN is operated for NASA by the Jet Propulsion Laboratory in Pasadena, California.
Trombka said it takes as much as eight hours of DSN time, and sometimes multiple passes to get all the data downlinked to Earth.
To the delight and surprise of many involved in the project, NEAR Shoemaker successfully soft-landed on Eros February 12. A decision was made two days later to have the probe make the first on-the-spot measurements of an asteroid using the crafts gamma ray spectrometer.
NASA extended the mission for up to 10 days. A further extension is possible; to assure that enough listening time from ground stations is found to receive quality science data.
"Once weve got good data, then maybe we can ask for more tracking time," Trombka said. A link between and Earth and NEAR Shoemaker might be maintained until the end of the month, he said.
Gawking at gamma rays
Trombka said the instrument is resting on or slightly above the asteroids topside of rock and dirt.
The equipment, mounted on NEAR Shoemaker's structure, is focused on a small circular patch of Eros. By using gamma rays, Trombka said, the device detects specific elements in the asteroids surface.
Measurements taken by the gamma ray spectrometer are expected to be 10 times more sensitive than what was possible when the spacecraft began orbiting Eros on February 14, 2000.
Signals from the equipment on Eros are being relayed by the DSN to mission controllers at APL in Laurel, Maryland.
APL designed, built and is managing the asteroid-surveying craft for NASA.
"Im looking at the spectra and they are looking very nice," Trombka said, saluting his engineering colleague at APL, John Goldsten, who has worked hard to get the gamma ray spectrometer working and interpreting the data, he said.
"Its going to take a number of months for us to get a good answer out of the data, and itll also help us interpret the orbital data much better now too," Trombka said.
Data has been sent back from Eros surface utilizing both the gamma ray spectrometer, as well as an onboard magnetometer, although the latter instrument has now been turned off.
Information from the magnetometer found no intrinsic magnetic field at Eros as it circled the celestial body for a year at various altitudes. No word yet as to whether or not the instrument detected magnetism at surface level. Finding a magnetic field would have important implications about the space rocks thermal and geologic history.
Long and winding road
NEAR Shoemaker made a journey of more than 2 billion miles (3.2 billion kilometers), and performed a yearlong observational campaign around Eros.
As the first asteroid orbiter, the probe was not built for landing. Scientists and engineers made a go-for-broke decision to attempt a touchdown on the rocky mini-world. They succeeded in soft-landing the probe onto Eros, with the craft plopping down on the asteroid at less than 4 miles per hour (between 1.5 and 1.8 meters per second).
The science data from the asteroids surface was received almost five years to the day after NEAR Shoemaker was launched on February 17, 1996.
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