A slight diversion, for the purposes of scientific discovery and sensitivity training.I know some of you do not care to be in proximity to spiders. However, since a few spiders will be accompanying us on our journey, I thought it best to point out the adventures of Astronaut Spiders Anita and Arabella - who gave their lives in the pursuit of scientific inquiry. Please read the article below, which takes us back 30 years. . . .Web Formation
Motor response is an indication of the functioning of the central nervous system. Drugs such as stimulants and sedatives affect the nervous system by causing degradation of certain motor responses. In an effort to study the effects of drugs, researchers have often utilized spiders as test subjects. The geometrical structure of the web of an orb-weaving spider provides a good measure of the condition of its central nervous system.
After reading an article in the National Geographic magazine describing the behavior of the spider, Judith Miles of Lexington High School, Lexington, Mass., suggested a study of the spider's behavior while weightless. Since the spider senses its own weight to determine the required thickness of web material and uses both the wind and gravity to initiate construction of its web, the lack of gravitational force in Skylab would provide a new and different stimulus to the spider's behavioral response.
The common Cross spider (Araneus diadematus
), an orb-weaving spider that produces a web of nearly concentric circles, was selected for the experiment. The Cross spider can live approximately 3 weeks without food if an adequate water supply is available. The female spider will build a web each day at approximately the same time, in the pre-dawn hours. The web is constructed in a very orderly fashion, starting with a bridge and frame. Using this rudimentary structure, the spider adds radial threads. A temporary spiral emanating from the hub is constructed next. It serves to give the spider a measure of the distance around the hub or central region of the web. Thus, the spider is able to judge the amount of silk required for the [continued below]Judith Miles wondered whether spiders could build webs while weightless. She proposed an experiment for Skylab which was performed by the second crew.Orb-weaving spiders spin webs familiar to everyone; however, their construction technique is a complicated one.
[continued from above] web, and it establishes the mesh size. The next step is the construction of the sticky, or catching, portion of the web. A free section of the web provides an area for spinning a signal thread from the spider's retreat to the limb of the web. This thread alerts the spider to the presence of prey in the catching spiral. The normal adult spider will utilize 66 to 98 feet of silk thread in constructing her web and will usually eat the sticky portion of the web daily. The web will generally consist of 30 to 40 radials and 25 to 35 spiral turns.
A specially constructed cage, provided with attachments for two portable utility lights, a camera-mounting bracket, and an ultrasonic actuator for a movie camera, was launched aboard Skylab. Two spiders, named Arabella and Anita, were each fed a housefly, installed in a small vial provided with a water-saturated sponge and an additional housefly, and launched in the Apollo spacecraft with the second Skylab crew.
On August 5, 1973, Scientist Pilot Garriott placed Arabella's vial in position on the cage and [continued below]Launched with the second Skylab crew were the space spiders Arabella and Anita, both common Cross spiders (
Araneus diadematus).The orbital home of Arabella and Anita aboard Skylab was a specially lighted cage. The two spiders rode in space in the small capsules to the right of the cage.A control spider on Earth built a perfect web in a Skylab cage to use as a comparison with those being built in space by Arabella and Anita.
[continued from above] fully expected her to move out into the cage from the cramped quarters. However, she refused to do so. After several hours Garriott forcibly shook her from the vial into the cage. Arabella bounced back and forth, moving erratically in a swimming motion before she affixed herself to the screen covering on the cage surface. The crew reported the next day that Arabella had constructed a rudimentary web in the corners of the cage. Her first complete web was observed after 2 days in the cage.
At this point, Garriott expressed interest in carrying this experiment beyond the planned protocol of terminating the experiment after allowing one spider to build three webs. As a result of this request, a new protocol was approved which involved feeding the spiders rare filet mignon, providing an additional water supply, deploying Anita at mid-mission, and returning both spiders together with samples of the webs.
Both spiders were subsequently fed, and on August 13, Garriott removed half of Arabella's existing web. She promptly ingested the remaining half and refused to rebuild. Garriott then provided Arabella with water, whereupon she proceeded to build a new web. On August 21, Arabella's web [continued below]Lost in a maze of electrical wires and cables, Scientist Pilot Garriott operated a TV camera to record the web-weaving of Arabella. Up and down had no meaning in the workshop.To initiate the spider experiment, Garriott attached Arabella's vial to the cage and tried to coax her out.At first, Arabella did not do too well at spinning a home in space.
[continued from above] was completely removed, and the web found in her cage the following day was observed to be her best to date.
On August 26, Arabella was returned to her launch vial, and Anita was placed in the cage. A videotape recording and 16-mm movies were made of Anita's first reactions to weightlessness. She, too, had to be forcibly ejected from her vial and, in fact, had to be picked off Garriott's arm before she could be induced to "swim" into place on the side of her cage. Anita performed in a manner similar to Arabella until September 16, when the astronaut found her dead in the cage. The dead spider was transferred to her launch vial for return to Earth.
Back on Earth, Arabella was found to have died also. Both spiders showed signs of dehydration, the only visible evidence of the cause of their death. Examination of the returned web materials indicated that the thread spun in flight was significantly [continued below]Once she had grown used to being weightless, Arabella spun webs that compared with those she had made on Earth.
[continued from above] finer than that spun preflight, giving positive evidence that the spider utilized a weight-sensing organism to size her thread.
It appeared that Arabella adapted quite well to the weightless environment. Control tests on Earth indicated that confinement in the launch vial did not affect the spider's ability to construct a quality web. Similar confinement, accompanied with vibration at the levels encountered during launch and followed by a "rest" period corresponding to the flight delay in deployment, resulted in an adaptation period of 2 to 3 days before the control spiders built webs comparable to their pretest quality. While Arabella performed her space task, the extended "rest" period experienced by Anita in her launch vial allowed her to build at least one quality web almost immediately when she entered the cage.
Had the original planning included keeping the spiders in the cage for the full mission rather than 3 to 5 days, a method could have been developed for feeding them and providing them with water in a more reliable fashion than was done.
Judy Miles' experiment received a great deal of attention both within NASA and in the world press and indicated that there was keen interest in space experiments involving living organisms. It also established that biological experiments involving simple life forms are compatible with manned spaceflight.Anita proved that she, too, could produce almost Earth-like webs once she had adapted to weightlessness.Both spiders and specimens of their webs were returned to Earth for Judith to examine. She was assisted by Raymond L. Gause, a physicist and her adviser at the Marshall Space Flight Center.