Senior Design I. Project: Mars Sample Return Mission. Group Members: Samuel Johnson (Group Leader) Jairus Adams Lamek Odak Demond Duke

Transcription

1 Senior Design I Project: Mars Sample Return Mission November 7, 2001 Group Members: Samuel Johnson (Group Leader) Jairus Adams Lamek Odak Demond Duke

2 Objectives of the Study The objective of this study is to design a containment system, commonly known as a canister, that will transport rock and soil samples from Mars to Earth. Specific:?? Determine the shape.?? Determine types of materials used.?? Be able to withstand high pressures.?? Zero leakage. Introduction People have wondered for years about if there is any kind of life form on Mars. There have been numerous projects completed by NASA to find out various aspects about Mars. In the past couple of years the interest of Mars exploration has increased and many questions have arose. This is why the Mars Sample Return Mission has come about. Hopefully with the completion of this mission, many question can and will be answered. To conduct these in depth studies, samples from Mars such as rock, soil and atmosphere need to be brought to Earth. Since there is a vast selection of these sort of samples, the development of tools and instruments to make the correct choices of scientific interest is needed. The initial identification of interesting objects will probably be conducted in the same manner that field geologist study rocks on Earth, which is by the usage of visual information such as color and texture. Also abilities to look at rock features on microscopic scales of millimeter or less and spectroscopy which is a technology using ultra violent, visible or infrared light to analyzed a rock s chemical composition are being developed. Protection of these samples is key because only pure Martian samples need to be studied. The containing apparatus (the canister) has to be thoroughly cleaned before launch because no contaminating particles should be present. Also the proper sealing agent has to be found so after the sample is collected and the container closes, nothing from the outside will get in. The question arises, how is the canister going to get to Mars and how will it return to Earth? Well, the launch into space is the simplest part of the whole task. A regular space shuttle will take off from Earth with the canister in a small compartment at the tip of the shuttle. When the shuttle is in the vicinity of Mars, the compartment will open and the canister and an ascent vehicle will be sent to this planet s surface to do the proposed job of attaining samples. Now the return to Earth, however, is a different story. There are two possible solutions. One way is to manufacture some sort of jet propellant made out of Martian air to lift the sample into orbit to be picked up by another spacecraft then return to Earth. The other plan is highly favored but seems more difficult. First one spacecraft will take off from our planet carrying a Land rover and an ascent vehicle (MAV). The rover will collect rocks and load them into the ascent vehicle. The ascent vehicle will also house the canister. Then after a couple of years, a second rocket takes off and heads to Mars carrying another Land rover just like the first one and an orbiter which circles Mars to await these rovers to complete their tasks. After completion, these ascent vehicles will go into an uncertain orbit around Mars and the orbiter will begin to try and hunt the MAV down. The difficulty with this notion is that

3 one of these MAV might not be found. Assuming that ascent vehicles are found, they will be picked up and proceed home. As the orbiter approaches or planet, it will use a gravitation assist from Earth to send it on a six-month orbit around the Sun. At the end of this time period, it will be properly be aligned to release these samples into a trajectory through the Earth s atmosphere without a parachute into a desert in the state of Utah. When finally picked up, NASA will begin the research and analysis stage will begin. Hopefully questions about life on Mars will be answered. Problem Statement What are the benefits of exploring Mars? Is it possible to find signs of life by sampling rocks and soil from Mars? What are the risks of bringing samples back from the Red Planet? How are we going to bring these samples back safely? These are among the many questions that are posed when discussing Mars. To accomplish this, NASA came up with the idea of the Mars Sample Return Mission. The mission is to get rock, soil and atmosphere samples from the planet and study them to look for life forms. This is where our design group comes in. Our focus is to develop a safe containment system (the shell) for these Martian samples to safely reach Earth. The material that we are going to use is beryllium-copper composite, which is a high strength copper based alloy, because it has formability, conductivity and strength. We are researching the proper shape, dimensions, height, thickness, etc. We also have to find the proper sealing agent because the shell has to be airtight so that there will be zero leakage to prevent release of contaminates into Earth. The containment system should hold up to 2 kilograms of Martian sample. This mission is to go to Mars, pick up some samples, bring back to Earth and test them. If only this was as easy as it sounds. Properties of Mars?? The gravity on Mars equals 3.71 m/s 2, as compared to Earth s gravity of 9.81 m/s 2?? Surface temperature (about 225 F? to 60 F?)?? Dust storms have wind speeds of 40 mph to 50 mph?? The atmospheric pressure on Mars is about 75 KPA, as compared to Earth s atmospheric pressure of 101 KPA. Comparing Different Alloys Chart of alloys Alloys Beryllium-copper Copper Brass Phosphor Bronze Nickel Silver Tensile Strength 140/220 KSI 60 KSI 120 KSI 145 KSI 99/111 KSI

4 Reason for choosing beryllium-copper?? Long service?? High tensile strength?? Good corrosion resistance?? Wide operating temperature range?? Non-sparking?? Easily fabricated?? Heat treatable?? Nonmagnetic Descriptions of Duties?? Meetings were set up and members were assigned specific topics to research dealing with Mars Sample Return.?? Researched and gathered background information on project - What is the purpose of the Mars Sample Return Mission - How is the canister going to get to Mars - How is the canister going to return to Earth?? The design for canister was decided upon. It will be either a sphere or a cylinder.?? The pressure of each design shape (a sphere and a cylinder) was figured out, using a Mechanics of Materials Book. The pressure would allow us to determine the design shape for the Mars Sample Return Canister.?? The type of material to be used for the construction of the canister was researched. The material that was decided upon was a beryllium-copper alloy because it is used on the shell of many aerospace and military vehicles.?? Researched the material for the project - Temperature tolerance - Tensile strength - Cost - Weight - Found important properties of the material Abstract Our main focal point with this project is to develop a design concept of a containment system (the shell or commonly called the canister) that will house materials obtained from Mars. We have to come up with the correct shape of the canister, find the proper materials, do proper

5 testing and stay in contact with NASA and the other schools associated with the Mars Sample Return Mission.