by Roger Wiens
This huge change in NASA breathed hope into what I had viewed as a dead-end job. I had coasted along for nearly two years, working to define the feasibility of our experiment, making phone calls and writing several papers on scientific aspects to be addressed. Don Burnett had had other things to do—he had several students and postdoctoral researchers working on understanding the intricate details of the formation of planets. NASA’s new outlook grabbed our attention.
The idea we were pursuing—bringing a sample of solar wind to Earth to analyze the Sun’s composition—was not new. It had first been suggested in the 1960s, not long after solar particles had been discovered. Solar wind consists of individual atoms accelerated out of the Sun by the tremendous magnetic fields radiating outward. Atoms speeding past the Earth travel about a million miles an hour, fast enough that they embed themselves into the surface of anything in their path in space.
The Apollo Moon missions had collected some solar-wind samples. The lunar soil returned by the astronauts was loaded with solar wind from eons of exposure to the Sun. However, the soil was an imperfect collector. Solar hydrogen was so abundant that the soil could not retain it, and nearly all of it had leaked out. Complicating matters was the fact that for the other elements it was impossible to tell how much was solar and how much native to the Moon. It became clear that a man-made collector, free of impurities, would do a much better job.
Dedicated collectors were initially proposed by Swiss scientists well before the first lunar mission. They had proved the feasibility of extracting and analyzing solar wind implanted into metal foils, and they had designed an extremely simple prototype for the Apollo missions. It consisted of a roll of aluminum foil hanging like a window shade from a pole planted into the lunar soil. When exposure was complete, the foil was simply rolled up and returned to Earth. The window-shade experiment, as it was dubbed, was flown on all but one of the Apollo missions to the lunar surface. It was one of the first experiments to be deployed by each pair of astronauts on the Moon, and its removal was one of the last things they did at the end of their stay. The first such experiment was deployed for only about two hours by the Apollo 11 astronauts. By the time of Apollo 16, the astronauts stayed on the surface long enough to expose the foil for forty-four hours.
Because the solar wind is so diffuse, less than a billionth of a gram embedded itself in a square inch of exposed material on the Apollo foils. Thus, even by using the dedicated collectors, only the most abundant elements could be analyzed. Additionally, the foils were contaminated by lunar dust kicked up by the astronauts, which prevented successful detection of most of the elements present in the solar wind. Further understanding of the Sun’s composition based on solar wind would have to await collection over long durations in interplanetary space.
Don Burnett was interested in pursuing this goal of collecting a larger and purer sample. However, in the mid-1970s, his colleague Marcia Neugebauer, the first woman scientist at JPL, became convinced that space-based instruments would be able to decipher the composition of the Sun without having to bring samples back to Earth. Eventually she came around to Don’s view, and by the 1980s Marcia was on board for a new solar-wind sample-return mission. Together Don and Marcia obtained some seed money, which enabled them to submit a full research proposal to NASA. Their project was funded the second time around, culminating in my job at Caltech.
With the sweeping changes in NASA in 1992, JPL began to woo scientists with prospective concepts who might become leaders of the new Discovery missions. Because Don and I were already receiving NASA funds for instrument development, we were attractive candidates—that is, until they heard that we were proposing a sample-return mission. The only time samples had previously been returned to Earth was the manned Apollo program, which had cost billions of dollars—the antithesis of a small, cheap project! How were we going to fit a sample-return mission into the Discovery program? We ourselves didn’t know.
Prior to NASA’s change in focus we had been considering piggybacking our sample return on some other mission. However, that ran against the grain of the new paradigm—such a strategy would surely lead to another “Christmas tree” spacecraft. For the purposes of the Discovery concept, we had to rethink our strategy entirely. We had to start from the ground up.
First, would it be possible to return an unmanned vehicle from space on a Discovery budget? We made a few phone calls to a military facility that was known to specialize in reentry capsules—the part of the spacecraft that returns to Earth from space flight. Although reentry capsules had not been used in the civilian space program since the Apollo days, the technology for them was alive and well on the military side. We were assured that we could fly a sample return as an independent small mission without too much difficulty.
With that settled, we began to define our project as a separate entity. Despite the added practical issues, we now had the luxury of sending the mission where we wanted it to go. Where could we fly to collect the most solar wind and have the easiest trajectory back to Earth? We knew we could not simply orbit the Earth—its surrounding magnetic fields deflect solar-wind ions. This “magnetosphere” extends past the highest satellites and has a tail extending behind the Earth well past the Moon. A collector in Earth orbit, even if it were high enough to be in the solar wind, would be contaminated by particles from the Earth every time it went into the magnetic tail. That ruled out orbits around the Earth or Moon. We could send the spacecraft into a Sun-centered orbit set to rendezvous with Earth in a year. But we had decided that we needed more than a year’s worth of solar wind. With a little greater difficulty we could use a trajectory to return to the Earth in two years. But these orbits gave us limited options as to when and where the capsule could reenter Earth, and because it would be at great distances from Earth, any communications required more significant resources.
There was one other trajectory our mission could take. Several robotic spacecraft from NASA’s Physics and Astrophysics divisions had taken up residence at a semistable point a million miles sunward of the Earth called the first Lagrangian (L1) point. This is the point at which the Sun’s gravity, the Earth’s gravity, and the centrifugal force of going around the Sun all balance each other. It would be ideal for solar-wind collection: it is near the Earth, yet always “upstream” so the Earth’s particles would not contaminate it. The return would also be appealingly easy: a spacecraft would simply need a slight push toward Earth, after which Earth’s gravity would take over, accelerating the object back to Earth’s surface. In fact, one spacecraft at the L1 point had been redirected to swing back by Earth, which then sling-shotted it to encounter a comet. With so many obvious advantages, this path became our default trajectory.
We also needed to decide what instruments our mission would carry if it was solely focused on collecting solar particles. In addition to exposing high-purity solar-wind collectors, Don wanted to develop an instrument to concentrate some of the particles onto a small target. The solar wind is so diffuse that even with two years of passive collection, the atoms of interest would comprise only a few parts per million of the surface layer of exposed collectors.
With some ideas on how we would fly an independent mission, we went back to JPL. The experts in interplanetary spacecraft navigation, JPL staff also had the most expertise in managing NASA projects, even if their experience was mostly in big, over-instrumented spacecraft. JPL was willing to help with the navigation, and their involvement would lend credibility to our cost estimates.
The first step was to figure out how much our spacecraft would cost. The managers at JPL had a virtual cost-estimating machine, into which you input all the parameters—the “machine” would then spit out the mission’s cost. We input sizes of instruments, planetary destination, and length of mission and waited for the number. The estimate was $190 million! That was way too much. The cap for the Discovery missions was $150 million. And there was not much we could do to lower the cost; ours was not a Christmas tree from whic
h one could throw off various instruments.
What made it cost so much? We suspected that it was the return trip to Earth, but to find out, we ran a little experiment. We input the same mission, but without bringing the samples back. Sure enough, it now came in at $100 million. The cost machine was telling us it would take $90 million just to return the samples—a ridiculous number. After all, the only sample-return missions to date had been the Apollo lunar landings, and those were in the billions of dollars. But after discussing the issue with colleagues at JPL and assuring them that capsule technology was alive and well on military space efforts, we were allowed to estimate a lower cost. With the consensus of several people, we came in with a figure of $140 million. We now fit into the Discovery mission envelope.
NASA decided to kick off its new plan with a meeting where people could present their ideas. A sort of beauty contest for new small mission concepts, it would be held at an institute in San Juan Capistrano, south of Los Angeles, in mid-November 1992, almost exactly half a year after Goldin took office. To NASA’s surprise, people came out of the woodwork with a staggering number of ideas. In all, seventy-nine ideas—including missions to the Moon, Mars, Venus, asteroids, comets, Mercury, and Jupiter—were presented. The small institute was packed to the gills with scientists, engineers, and space enthusiasts from all corners of the country. Almost none of the mission concepts were for returning samples, however, and ours was the only one to propose solar-wind collection.
Many of the missions were clearly better developed in terms of their spacecraft design, timelines, and instrument details. But despite the odds, we had done our best, and we eagerly awaited the results.
On a rainy day in December I went into Don’s office and saw the look on his face. We had not placed in the top ten. We read the letter from NASA Headquarters and were shocked to hear that the review panel had judged our mission to be eminently feasible, including the sample-return aspect, but had given us a low score for scientific value. The review had determined that several spacecraft currently being readied for launch would accomplish all of our objectives to study the Sun without having to bring back samples.
That was completely wrong, and despite his years of experience getting a fair fraction of his proposals rejected—and his disappointment at such outcomes—Don felt compelled to action, this once. He wrote a letter to the head of the committee carefully pointing out the error. And we waited, though without much hope.
In the meantime, we received another blow. The NASA office in charge of instrument-development projects, a separate office that had funded me for the first two years, had decided to use the results of the beauty contest to help judge which instrument projects to support. Although the independent reviews of our proposal had been positive, the panel looked at the contest results and rejected our proposal. We received the rejection letter just after Christmas. The elimination of our instrument proposal funding meant that money would run out for me within a couple of months. For the second time in three years, it looked as if I would be out on the streets, jobwise.
About a week after the rejection letter from NASA’s instrument office, we received a letter from the head of the mission concept review team. Amazingly, the review panel had taken Don’s letter into consideration, confirmed its claims, and changed our score from low to high in one fell swoop. We were back in the running! Within another week the contest winners were officially announced. And instead of ten awards, NASA’s new list of favorite small missions consisted of eleven missions—we had been squeezed in.
Things would never again look that bleak. We resubmitted our instrument-development proposal to NASA the following year, with very few changes, and it was rated the highest of all the proposals because we were a Discovery concept winner.
The disappearance of the Mars Observer spacecraft in August 1993 now served to strengthen the winds of change toward small missions. NASA went ahead with its plans to compete the new Discovery class of small planetary missions. There would be funding for new flights about every other year, with the first round of full proposals due in the fall of 1994.
We were on our way, preparing for the first Discovery mission selection.
Our mission was unique: no one else aspired to capture samples of the Sun. The purpose was not just to learn the composition of our nearest star. We knew that each of the planets had been formed, along with the Sun, from a cloud of gas and interstellar dust. Each body had a unique composition—its own chemical signature, so to speak. But we could understand much more about the planet-forming process—we could read those signatures—if we knew more about the original starting material. The Sun, which contains more than 99 percent of the material in the solar system, must have captured a representative sample of the primordial nebular cloud. The outer layers of the Sun are not changed by the nuclear burning going on deep in the interior. So, we reasoned, if we could capture a sample of this outer portion of the Sun in the form of solar wind, we would, in effect, have a sample of the nebular cloud—the starting material we were seeking. So we christened our mission with a name evocative of primordial beginnings: Genesis.
*NASA eventually overcame both of these problems. The Galileo spacecraft, which could still communicate with Earth at the rate of a few bits per second on its backup antenna, was programmed to use highly efficient data compression. And the HST was fitted with corrective lenses several years later.
chapter
three
MISSION SELECTION
BY THE SUMMER OF 1994, WE WERE WORKING FULL-OUT ON our Genesis proposal. The occasion was the first competition for complete Discovery missions. We had come a long way in pulling together a mission concept. As one of the beauty contest winners, we had been courted by JPL with an offer of half again as much funding as we had already won so that JPL could become involved in a more significant way. As we lacked a plan for deploying or stowing the solar-wind collectors, and didn’t even know what the collectors should look like, we decided to take up this offer and go to their mechanisms division.
We had our first meeting with the mechanical engineers on a late afternoon in a deserted Caltech classroom. We were working on a truly unique main instrument. It was not a camera or some fancy ion or gamma-ray detector. Instead, all we wanted to do was expose high-purity materials to the Sun for long periods of time and then retract them into a capsule to return them to Earth. Foremost on the engineers’ minds was how the hardware would survive the launch vibrations, the rigors of reentry, and the slight shock of landing after parachuting to the ground. For collector materials, we were considering silicon wafers—the stuff computer chips are made from. These wafers are some of the purest materials on Earth, and they were readily available. But silicon wafers are delicate, brittle slices of pure silicon crystals—not a favorite with the mechanical engineers because of their fragility.
After a lengthy discussion, we eventually settled on a design for collector arrays. They would be a little under 3 feet in diameter inside a capsule almost 5 feet across. The plan consisted of several arrays of wafers—about eighty 4-inch wafers per array—that rested on top of each other inside a canister. The canister would open up like a clamshell, allowing the arrays to rotate out from a vertical shaft near one side, exposing a large area. Three them could be shaded under the top array except when their type of solar wind was present,* at which time they would be deployed into the sunlight. The top layer collected solar wind continuously.
While we worked with JPL on preliminary concepts for the arrays, we developed a working relationship with Lockheed Martin Astronautics in Denver. Lockheed had just bought up another company that had made entry capsules for the military, and it was eager to get into the NASA competition. So the distribution of responsibilities would be as follows: JPL would manage the project under Don’s leadership, would be in charge of the flight navigation for the spacecraft, and would build the canister to house and deploy the solar-wind collectors. Lockheed Martin would design the spacecraft, including th
e propulsion system, the navigation equipment, the communications and onboard computer, and, of course, the capsule and reentry system. The rocket to boost the spacecraft away from Earth would be contracted from Boeing, but by then unmanned rockets were more of an assembly-line product, so not much discussion was needed there.
There was one more important feature: the experiment would need several monitors to log the behavior of the solar wind while the “bird” was in flight. At Marcia’s suggestion we decided to work with Los Alamos National Laboratory, which had built similar instruments in the past. Los Alamos would also help with a third instrument, the solar-wind concentrator I was developing.
During the concept phase, our support staff at JPL and Lockheed Martin consisted of the minimum number of people—basically their “dreamworks” proposal hotshots who could extract the critical information from the various experts in propulsion, thermal, navigation, and other specialties. The hotshots sent the information on to us. Actually pulling the information together into a coherent proposal was going to fall to Don and me.
The word-processing era was just coming of age. Having been born closer to the computer age than Don, I took charge of publishing the volumes, while he reviewed everything and coordinated inputs. We had graduated from the TRS-80 computer to a “386” that was connected to a printer. The most recent advance was an e-mail hookup. E-mail at this point consisted of simple messages; attachments were as yet unheard of. So everything but simple text was passed back and forth in hard copy. Our proposal had hundreds of figures, tables, and summary boxes. Wrestling with the word-processing software was a struggle; just when I thought everything was set, a box would jump to the next page, leaving a third of a page of blank space and pushing us over the page limit.