Genesis (spacecraft)

This article is about the NASA sample return mission. For the space station prototypes, see Genesis I and Genesis II. For other uses, see Genesis (disambiguation).

Genesis

In its collecting configuration, the Genesis spacecraft exposed several types of solar wind collectors, as well as ion and electron monitors.
Operator	NASA / JPL
Major contractors	Lockheed Martin
Mission type	Sample return
Launch date	2001-08-08, 16:13:40 UTC ( ago)
Launch vehicle	Delta II 7326
Launch site	Cape Canaveral SLC 17A
Mission duration	December 3, 2001 – April 22, 2004 ( 2 years, 5 months, and 19 days) (currently in sleep mode)  Sample return  (completed 2004-09-08)
Satellite of	Earth L1, Sun
Landing site	Dugway Proving Ground (crashed)
COSPAR ID	2001-034A
Homepage	http://genesismission.jpl.nasa.gov/
Mass	494 kg (1,089 lb)
Power	254.0 W (Solar array / Ni-H2 battery)
Instruments
Spectral band	GE-2, Trans. 9, C-band
References:

Genesis was a NASA sample return probe that collected a sample of solar wind and returned it to Earth for analysis. It was the first NASA sample return mission to return material since the Apollo Program, and the first to return material from beyond the orbit of the Moon. Genesis was launched on August 8, 2001, and crash-landed in Utah on September 8, 2004, after a design flaw prevented the deployment of its drogue parachute. The crash contaminated many of the sample collectors, and although most were damaged, many of the collectors were successfully recovered.

The Genesis science team demonstrated that some of the contamination could be removed or avoided, and that the solar wind could be analyzed using a variety of approaches. It is relatively easy to detect the solar wind, but the precision measurements are difficult and techniques are still being refined in laboratories worldwide. Nonetheless, in March 2008 scientists stated that they believed that all of the mission's major science objectives would be achieved successfully.

Objectives

A Genesis collector array in the Genesis clean lab at the Johnson Space Center (photo courtesy of NASA). The hexagons consist of a variety of ultra-pure, semiconductor-grade wafers, including silicon, commercial “sapphire” (i.e. corundum), gold on sapphire, diamond-like carbon films, and other materials.

The mission’s primary science objectives, as paraphrased from the original proposal fact sheet, were:

• To obtain precise solar isotopic abundances of ions in the solar wind, as essentially no data having a precision sufficient for solving planetary science problems are available;
• To obtain greatly improved solar elemental abundances by factor of 3-10 in accuracy over what is in the literature;
• To provide a reservoir of solar matter for 21st century science to be archived similarly as the lunar samples.

Note that the mission's science objectives refer to the composition of the Sun, not that of the solar wind. Scientists desire a sample of the Sun because evidence suggests that the outer layer of the Sun preserves the composition of our early solar nebula. Therefore, knowing the elemental and isotopic composition of the outer layer of the Sun is effectively the same as knowing the elemental and isotopic composition of our nebula. We could then use that data to model how planets and other Solar System objects formed and then extend those results to understanding stellar evolution and the formation of planetary systems elsewhere in the universe.

Clearly, the ideal scientific option would be to send a spacecraft to the Sun itself and collect some solar plasma; however, obtaining solar matter is difficult because of the intense heat of the Sun’s superheated gases, as well as the dynamic electromagnetic environment of the solar corona, whose flares regularly interfere with the electronics of distant spacecraft. Fortunately, the Sun continuously sheds some of its outer layer in the form of solar wind, and data collected prior to the Genesis mission suggests that the rock-forming elements are thought to maintain their relative proportions throughout the process of solar wind formation.

Accordingly, in order to meet the mission science objectives, the Genesis spacecraft was designed to collect solar wind ions and return them to Earth for analysis. Genesis carried several different solar-wind collectors, all of which passively collected solar wind; that is, the collectors sat in space facing the sun, while the ions in the solar-wind crashed into them at speeds over 200 km/s and, on impact, buried themselves in the surface of the collectors. This passive collection is a process similar to that used by the semi-conductor industry to make certain types of devices, and a simulation of the process is given by the free-access program SRIM.

Most of the Genesis collectors continuously sampled all of the solar wind which the spacecraft encountered (the "bulk solar wind"). However, the spacecraft also carried three arrays of collectors which were deployed when specific “regimes” (fast, slow, coronal mass ejections) of solar wind were encountered, as determined by the electron- and ion- monitors on board. These deployable collector arrays were designed to provide data to test the hypothesis that the rock-forming elements keep their relative proportions throughout the processes which form the solar wind.

There was a third type of collector on Genesis: the concentrator, which collected bulk solar wind, but was discriminating in that it electrostatically repelled hydrogen and had enough voltage to focus the lighter solar wind elements onto a small target, concentrating those ions by a factor of ~20. The objective of the concentrator was to bring back a sample with enhanced amounts of solar wind ions to make it possible for analysts to precisely measure the isotopes of the light elements.

Operation

Mission profile

File:Genesis Launch.jpg

The launch of Genesis

Genesis was a Discovery-class mission of the NASA Jet Propulsion Laboratory (JPL) at the California Institute of Technology. The spacecraft was designed and built by Lockheed Martin Space Systems at a total mission cost of US$264 million.

The Genesis mission's trajectory and flight plan

NASA launched the craft on a Delta II 7326 rocket on August 8, 2001 at 16:13:40 UTC from Cape Canaveral. Following launch, Genesis cruised to the Earth-Sun L₁ then performed a Lissajous orbit insertion maneuver, entering an elliptical orbit about L₁ on November 16, 2001. Genesis exposed its collector arrays on 3 December, and began collecting solar wind particles. The collection process ended after 850 days, on April 1, 2004, with the spacecraft completing five halo loops around L₁. Genesis began its return to Earth on April 22, 2004. The return phase included an orbital detour toward the Earth L₂ so that the craft could be recovered during the daytime, as a direct approach would have forced it to be recovered at night. After completing one halo loop about L₂, the spacecraft returned to Earth for a planned September 8, 2004 recovery.

Recovery phase

The planned mid-air retrieval was extensively rehearsed.

Following completion of the collection phase, the collector arrays were stowed in a sample return capsule, and the spacecraft returned to Earth. As the capsule was approaching Earth and at the first stages of re-entry, all appeared well.

Extensive planning had been conducted for the capsule's retrieval. A normal parachute landing might have damaged the delicate samples, so the mission design called for a mid-air retrieval of the sample return capsule. About 33 km above the ground, a drogue parachute was to be deployed to slow descent. Then, at a height of 6.7 km, a large parafoil was to be deployed to slow descent further and leave the capsule in stable flight. A helicopter, with a second helicopter as a backup, was then to attempt to catch the capsule by its parachute on the end of a five-meter hook. Once retrieved, the capsule would have been soft-landed.

The Genesis sample return capsule, imaged moments before its impact.

The sample return capsule entered Earth's atmosphere over northern Oregon at 16:55 UTC September 8, 2004, with a velocity of approximately 11.04 km/s (24,706 mph). Due to a design flaw in a deceleration sensor, parachute deployment was never triggered, and the spacecraft's descent was slowed only by its own air resistance. The planned mid-air retrieval could not be carried out, and the capsule crashed into the desert floor of the Dugway Proving Ground in Tooele County, Utah, at about 86 metres per second (311 km/h (193 mph)).

The capsule broke open on impact, and part of the inner sample capsule was also breached. The damage was less severe than might have been expected given its velocity; it was to some extent cushioned by falling into fairly soft muddy ground.

Sample extraction and results

The sample return capsule broke open when it impacted on the Utah desert floor. The capsule was about 1.5 m (4.9 ft) in diameter and has a mass of 275 kg (600 lb).

Unfired pyrotechnic devices in the parachute deployment system and toxic gases from the batteries delayed the recovery team’s approach to the crash site. After all was made safe, the damaged sample-return capsule was secured and moved to a clean room for inspection; simultaneously a crew of trained personnel scoured the site for collector fragments and sampled the local desert soil to archive as a reference by which to identify possible contaminants in the future. Recovery efforts by Genesis team members at the Utah Test and Training range – which included inspecting, cataloging and packaging various collectors — took four weeks.

Initial investigations showed that some wafers had crumbled to dust on impact, but others were largely intact. Desert dirt entered the capsule, but not liquid water. Because the solar wind particles were expected to be embedded in the wafers, whereas the contaminating dirt was thought likely just to lie on the surface, it was thought possible to separate the dirt from the samples.

The analysis team hoped to extract some useful data from the capsule. Roger Wiens, of the Los Alamos National Laboratory stated on September 10, 2004 that because much of the inner canister was still intact, and despite serious contamination, "We should be able to meet many, if not all, of our primary science goals". On September 21, 2004 the extraction was said to be going well, with wafer fragments beginning to be extracted from the science canister. NASA announced on January 27, 2005, that a first sample piece of an aluminum wafer was sent to scientists at Washington University in St. Louis for analysis.

On April 20, 2005, NASA announced that scientists at the Johnson Space Center in Houston had removed the four solar-wind collectors from an instrument called the concentrator and found them in excellent shape. The concentrator's targets collected solar-oxygen ions during the mission and would be analyzed to measure solar-oxygen isotopic composition, the highest-priority measurement objective for Genesis.

After three years, scientists at Washington University published detailed neon and argon isotope fractionation findings. Argon and neon isotopes in samples of three types of solar wind (fast, slow, and coronal mass ejections from the Sun’s surface) were captured and quantified. The findings effectively discount some theoretical models of stellar genesis. This more precise data complements knowledge gained from earlier lunar argon measurements.

Kevin McKeegan, UCLA Cosmochemistry Professor, announced on 10 March 2008 that analysis of a silicon wafer from Genesis showed that the Sun has a higher proportion of oxygen-16 than does the Earth. The measurement was made after a beam of cesium atoms was used to remove the upper 20 nm of the wafer. This implies that an unknown process depleted oxygen-16 from the Sun's disk of protoplanetary material prior to the coalescence of dust grains that formed the Earth.

Unexpectedly, it was not terrestrial desert soil introduced in the crash that proved most difficult to deal with during the sample analysis process but the craft's own flight-introduced compounds such as lubricants and craft-building materials.

Fate of spacecraft bus

After releasing the sample return capsule on September 8, 2004, the spacecraft bus traveled back toward the Earth-Sun Lagrange Point (L1). A trajectory correction maneuver was performed on November 6, 2004, permitting the spacecraft bus to eventually leave L1 if it was not used for an extended mission. Final commands were transmitted to the bus on December 2, 2004, placing Genesis into hibernation. While in this "safe" mode, it will continue transmitting information about its condition, autonomously pointing its solar arrays toward the Sun. The spacecraft bus left L1 around February 1, 2005, staying in a heliocentric orbit leading the Earth.

Mishap Investigation Board (MIB)

Genesis Principal Investigator Dr. Donald Burnett sorting through the debris from the sample canister.

Top: a view of the Genesis capsule and bus. Bottom: a closeup of the type of accelerometer that was installed backwards, with a pencil shown for scale.

A 16-member NASA Mishap Investigation Board (MIB) was appointed, including experts on pyrotechnics, avionics, and other specialties. The MIB started its work on September 10, 2004, when it arrived at Dugway Proving Ground. It determined that all scientific hardware meant to be curated by the Johnson Space Center could be released and were not needed for the work of the board. Both JPL and Lockheed Martin began to prepare flight data and other records for the MIB.

It was announced by the MIB on September 20, 2004, that the capsule, having had the science material extracted, would be moved to the Lockheed Martin Space Systems facility near Denver, Colorado, for MIB use.

A first possible root cause of the failed deployment of the parachutes was announced in an October 14 press release. Lockheed Martin had built the system with an acceleration sensor's internal mechanisms wrongly oriented (a G-switch was installed backwards), and design reviews had not caught the mistake. The intended design was to make an electrical contact inside the sensor at 3 g (29 m/s²), maintaining it through the maximum expected 30 g (290 m/s²), and breaking the contact again at 3 g to start the parachute release sequence. Instead, no contact was ever made.

The same general parachute concept was also used on the Stardust cometary sample return spacecraft, which landed successfully in 2006.

NASA investigation board chair Michael Ryschkewitsch noted that none of the stringent review procedures at NASA had picked up a mistake, saying, "It would be very easy to mix this up."

This mishap is similar to the original event that inspired Edward A. Murphy, Jr. to formulate the now-famous Murphy's Law: an accelerometer installed backwards. On January 6, 2006, Ryschkewitsch revealed that a pre-test procedure on the craft was skipped by Lockheed Martin, and he noted that the test could have easily detected the problem.

External links

• Genesis Mission Profile by NASA's Solar System Exploration