13 February 1998 - Gregory A. Smith

Europa - Ice Rafting

The full data sets from Galileo's first three orbits (G1, G2 & E3) are now validated and available!

The Galileo Europa Mission , an extension of the primary mission, is well on its way. The Galileo spacecraft successfully completed its second encounter of its extended mission with Jupiter's moon, Europa, on February 10, 1998.

The first Europa encounter of the extended mission occured on December 16, 1997, when the Galileo spacecraft made the closest ever flyby of Europa. The Galileo Europa Mission will include 7 more consecutive flybys of Europa

The Galileo Europa encounters schedule:

E12 Europa - 16 December 1997
E13 Europa - 10 February 1998
E14 Europa - 29 March 1998
E15 Europa - 31 May 1998
E16 Europa - 21 July 1998
E17 Europa - 26 September 1998
E18 Europa - 22 November 1998
E19 Europa - 1 February 1999

The last signal received from the Mars Pathfinder spacecraft occurred on Sol 93, which was October 7, 1997.

The first Pathfinder science papers were published last month in Science Magazine of 5 December 97.

"Taken together, the rounded pebbles and cobbles and the possible conglomerate, the abundant sand- and dust-sized particles and models for their origin, and the high-silica rocks all appear consistent with a water-rich planet that may be more Earth-like than previously recognized, with a warmer and wetter past in which liquid water was stable and the atmosphere was thicker." - Reference: Overview of the Mars Pathfinder Mission and Assessment of Landing Site Predictions - Science Online

Mars Pathfinder is the first mission to land on Mars since two "Viking" spacecraft touched down there in 1976.

Last month the Mars Global Surveyor flight team celebrated as Surveyor completed its 100th orbit around Mars. - Reference: Current Flight Status Report (30 Jan 98)

The MGS mission requires the spacecraft to "aerobrake" using the thin Martian atmosphere to slow the spacecraft and place it into a circular orbit for mapping. On 11 October 1997, the Mars Global Surveyor flight team paused the aerobraking procedures because a damaged solar panel began to bend backward while passing through a temporarily denser atmosphere than had been predicted.

After several weeks of analyzing the situation, the flight team decided to resume aerobraking at a more gentle pace. On 7 November 1997, aerobraking was resumed, but with the spacecraft's low point to be at an average altitude of 120km rather than the 110km altitude originally planned. This higher altitude reduces the air resistance pressure on the spacecraft by 66% but increases the amount of time required to complete the aerobraking phase.

Under the new mission plan, aerobraking will be suspended in May, 1998 for six months to allow the spacecraft orbit to drift into a better position for mapping. During this period, from May 1998 to November 1998, the spacecraft and flight team will be in a "Science Phasing" period and will collect as much science as possible to maximize the efficiency of the mission.

Aerobraking will resume from November 1998 to March 1999 when the spacecraft will be in its proper mapping orbit. At that point the spacecraft will circle Mars every two hours and will have a high point of 450km.

"NEAR spacecraft state is nominal." - NEAR Weekly Report - February 6, 1998

The NEAR spacecraft successfully completed its January 23, 1998 Earth/Moon Swingby and has provided us with spectacular images of the Earth and Moon.

The NEAR team imaged the Earth and Moon with the spacecraft's MultiSpectral Imager and Near-Infrared Spectrograph during the flyby (watch for an Earth/Moon movie in the NEAR future!).

NEAR's imager and spectrograph will be calibrated with "ground truth" measurements known of Earth and moon geological features.

Over the next year the NEAR scientists and engineers will be developing and testing software and finalizing procedures for the year-long encounter with Asteroid 433 Eros .

Read about the NEAR spacecraft's Gamma Ray Spectrometer detecting major gamma-ray bursts at: The Planetary Society - Headlines.

NEAR's study of Eros will be the first in-depth examination of a near-Earth asteroid and is expected to yield information that will help scientists better understand the evolution of our solar system. NEAR, which is being tracked by NASA's Deep Space Network, is the first mission in the Space Agency's Discovery series.

"The Lunar Prospector spacecraft continues to perform very well" -
February 9, 1998 Lunar Prospector Status Report #19.

The Lunar Prospector spacecraft launched from the new Spaceport Florida commercial launch pad at Cape Canaveral, FL., atop a Lockheed Martin Athena II launch vehicle. The spacecraft completed almost three-quarters of a revolution around the Earth when the Trans Lunar Injection stage fired to put the spacecraft on a 105 hour coast to the Moon. One minute and 15 seconds after separating from the third stage of the launch vehicle, all the science instruments were successfully activated.

The Lunar Prospector will conduct a low polar orbit investigation of the Moon. Data from the spacecraft will allow the compositional mapping of the Moon, including possible water ice deposits trapped in permanently shadowed areas near the lunar poles. Other instruments will measure the crustal magnetic field, gravity fields and radon outgassing.

The Cassini spacecraft remains in excellent health as it travels on its Saturn-bound trajectory at a speed of approximately 120,000 kilometers per hour (about 75,000 miles per hour).

Reference: Cassini Status Report - February 3, 1998

Deep Space One is the first deep space mission of NASA's New Millennium Program. The New Millennium Program (NMP) is an agressive technology demonstration established to validate advanced technologies while returning science data.

To be launched in July, 1998, Deep Space 1 will validate 12 advanced technologies and instruments while conducting a flyby of asteroid McAuliffe, then Mars , and finally by comet West-Kohoutek-Ikemura.

"The goal is at least one flight each month" - Kane Casani, manager of the New Millennium Program. Reference: NMP press release - February 10, 1995 (One flight each month will make keeping SPACEUPDATE up-to-date a much more demanding job!)

Planet-B is the first Japanese space mission to Mars. A Mars orbiting aeronomy mission, Planet-B is designed to study the martian upper atmosphere and its interaction with the solar wind. Instruments on the spacecraft will measure the structure, composition and dynamics of the ionosphere, aeronomy effects of the solar wind, the escape of atmospheric constituents, the structure of the magnetosphere, and dust in the upper atmosphere and in orbit around Mars. The mission will also be returning images of Mars' surface and the martian moons Phobos and Deimos.

Planet-B will initially be put into an elliptical geocentric 7000 km x 400,000 km parking orbit with its apogee just beyond the orbit of the Moon. Assuming that launch occurs in the early August launch window as scheduled, the first lunar swingby will take place in September. In December it will gain more energy on a second flyby of the Moon, and will then swing by close to the Earth and slingshot into an escape trajectory towards Mars. It is scheduled to arrive at Mars on 11 October 1999.

Planet-B will be inserted into a highly eccentric Mars orbit 300 km x 47,500 km with an inclination of 138 degrees and a period of just over 38 hours.

The nominal mission is planned for one martian year (approximately two Earth years). An extended mission may allow operation of the mission well beyond the original two years.

The Mars Surveyor '98 Orbiter will be launched in December of 1998 on a Delta II rocket. It will be followed about 3 weeks later by the Mars Surveyor Lander '98, also launched by the same rocket system. Nasa bills this duo as a "2 for 1" project since one team (at JPL) will supervise both missions, and much of the hardware is redundant. They also note that with a mission cap of $184 million both of the '98 Surveyor spacecraft will cost less than 1997's Mars Pathfinder.

Every 26 months a "transfer opportunity " occurrs because of the alignment of Earth and Mars. The '98 Surveyor launches take advantage of this window. The Orbiter spacecraft will have a 10 month journey to the red planet. On about Sept. 23 1999, it will commence an aerobraking manuver to acheive Mars orbit insertion (MOI). This eliptical capture orbit will be incrementally reduced by successive passes through the thin upper atmosphere. After about 2 months the orbit will be circularized using onboard hydrazine thrusters into a circular polar mapping orbit (altitude ~ 400 km.)

The overall theme of the 2 part Mars Surveyor '98 mission is "volatiles and climate history". The orbiter's role in this scheme is twofold. Once it acheives its final orbit it will commence surface mapping, while another instrument package is analyzing the atmospheric composition and weather. At the same time it will act as a data link to relay information from its companion spacecraft (Mars Surveyor '98 Lander) back to Earth. The atmospheric sounding and imaging phase is scheduled to last for one Mars year (687 Earth days).

In its role as a data relay the Orbiter should be operational for at least 5 years. This will allow an encore data relay performance for the '01 Mars mission, arriving in January 2002.

- Jim Warnock

While the Mars Surveyor `98 Orbiter surveys the planet from on high, the Mars Surveyor `98 Lander will conduct its mission from the Martian surface.

The Mars Surveyor `98 Lander must decellerate from 7 km/sec to 2.4 meters/sec for a safe Martian touchdown. This will be accomplished by aerobraking with an ablative heatshield, a parachute deployment and a final rocket propulsion firing for a soft landing. The destination is ~80 degrees S., the first lander in a polar region. This high latitude region has "layered terrain" which should have water ice near the surface and might show evidence of past climatic variations. Certainly new insights will be gained into the seasonal ice caps (CO2 ice) and polar weather. The lander will have a robotic arm for trenching, cameras, and atmospheric sensors. Its primary mission is 90 days.

- Jim Warnock

Piggybacked on the Mars Surveyor `98 Lander spacecraft are 2 "microprobes". These autonomous impactors are to present many "firsts" for planetary scientists. The ingenious delivery system saves the money that a dedicated launch would cost (in the true spirit of hitchhiking!). After 11 months in transit the microprobes separate from the lander spacecraft for a passive atmospheric entry. These high tech devices are designed to survive an 80,000 G impact and be the first probe to gather subsurface data. Once again, investigators hope to discover clues to Mars' past climate, including the apparent mystery of the "dissapeared" surface water. Does the water that may have caused the erosional features we can see today now exist as permafrost? If so, what implications would that have for possible life forms? Information on soil temperature, ices, air pressure, and solar measurements will all be relayed to the Orbiter, which will be overhead 10 times a day to relay the data back to Earth.

- Jim Warnock

NASA sample return mission to Comet Wild-2.

LUNAR-A

Mars 2001 Orbiter

Mars 2001 Lander

NASA AND JAPAN ASTEROID SAMPLE RETURN MISSION

MUSES-C will be launched on a Japanese M-5 launch vehicle in January 2002 from Kagoshima Space Center, Japan and touchdown on the asteroid Nereus in September 2003. A NASA-provided miniature robotic rover will conduct in- situ measurements on the rocky surface and collect samples.

The asteroid samples will be returned to Earth by MUSES-C via a parachute-borne recovery capsule in January 2006.

Reference: NASA press release 97-95

- Gregory A. Smith

CONTOUR multiple comet mission.

The Europa Orbiter is a JPL mission to orbit Europa.

Selene is an ISAS (Japan) Lunar orbiter and lander mission.

Rosetta is a European Space Agency (ESA) mission designed to rendezvous with comet Wirtanen and perform remote sensing investigations as well as carrying a probe to land on the comet's surface and perform in situ measurements. Flybys of two asteroids on the way to the comet, with gravity assists from Mars and Earth, are also planned.

The mission is named for the Rosetta Stone which was the key to deciphering Egyptian hieroglyphics. (The stone was named for the seaside town of Rosetta, Egypt, where it was found by Napoleon's troops in 1799.)

- Gregory A. Smith

Mars Surveyor 2003 lander/rover

The Deep Space 4/Champollion mission is designed to test advanced technologies for landing on small bodies in the solar system, and for collecting samples of those bodies and returning them to Earth.

DS4/Champollion will rendezvous with periodic Comet Tempel 1 in late 2005. After several months spent studying the cometary nucleus from orbit, will deploy a 100 kg spacecraft that will make the first ever landing on the surface of a comet. The lander will take close-up images of the surface and drill one meter into the nucleus to collect samples of cometary ices and dust. These samples will be examined by instruments onboard the DS4/Champollion lander and the results radioed back to Earth. Up to 100 cubic centimeters of material will be collected and returned to Earth in 2010.

The DS4/Champollion is named after Jean Francois Champollion, a French Egyptologist who, collaborating with Thomas Young, deciphered the ancient Egyptian hieroglyphic and demotic text on the stone by comparing it with the known Greek text on the same stone.

- Gregory A. Smith

Mars Surveyor 2005 lander/rover/sample return.