RBE 595: Space and Planetary Robotics Lecture 9

1. RBE 595: Space and Planetary RoboticsLecture 9 Professor Marko B Popovic A term 2019

2. What is next? SpaceX To Launch Crewed Starship Flight (2020) SpaceX CEO Elon Musk during the September 28, 2019, Starship event announced his plans… MK 1 is the forerunner of the spaceship that may bring the first human visitors—possibly colonists—to Mars. SpaceX plans to use it to sell satellite launches in 2021 and one paying customer, Japanese billionaire YusakuMaezawa, plans a Starship trip around the Moon in 2023. “This thing is going to take off fly to 20km and come back and land, in about one or two months,” Musk told the crowd. “That will be pretty epic, to see that thing take off and come back.” “This is really a new approach to controlling a rocket [while landing],” he said. “More akin to a skydiver than flying a plane…We’re doing a controlled fall. You are trying to create drag instead of lift. It’s the opposite of an airplane.” https://www.popularmechanics.com/space/rockets/a29284744/elon-musk-starship-reveal/

3. Musk says the key to a reusable orbital rocket is to combine extremely efficient engines with a low-mass structure. This creates the opportunity for profitable launches of massive payloads. Musk says “there is a clear path” to launches of 150 tons with full reusability to orbit and back. Musk says the material that makes up Starship is also vital due to its low weight and cost compared to carbon fiber. But not any steel will do: This is a nickel/chromium alloy called 301. “The best design decision of this whole thing was 301 stainless steel,” he said. "Unlike other steel, which gets brittle, 301 gets stronger at low temperatures.”

4. NASA Mars 2020 Rover LaunchesToward Mars (2020) The rover has seen an upgrade which includes a stronger and "more capable" wheel design and also allows for drilling so that samples of Martian rocks and soil can be examined. Test oxygen production from the Martian atmosphere The Mars 2020 mission landing system includes a parachute, descent vehicle, and an approach called a "skycrane maneuver" for lowering the rover on a tether to the surface during the final seconds prior to landing. ExoMars Reaches the Martian Surface (2021) (collaboration between the ESA and Roscosmos)

5. Roscosmos Begins Offering Space Tours (2021) A Luxury Hotel on the ISS? The proposed luxury tourist hub (foreground) will closely resemble the Science and Power Module, NEM, (background) scheduled for delivery to the International Space Station around 2021. The entire trip, lasting from one to two weeks will cost $40 million per person and going with the spacewalk option and an extended month-long stay will set the traveler back an additional $20 million. The 20-ton, 15.5-meter-long module would provide 92 cubic meters of pressurized space. It would accommodate four sleeping quarters sized around two cubic meters each and two “hygiene and medical” stations of the same volume. Each private room would also have a porthole with a diameter of 228 millimeters (9 inches), while the lounge area of the module would have a giant 426-millimeter (16-inch) window.

6. The James Webb Telescope Begins Its Mission (2021) Webb will be launched with the assistance of the European Space Agency (ESA) who will provide an Ariane 5 rocket to set the Webb, the successor to the Hubble Telescope, into orbit. SpaceX Launches a Mission to Mars (2022) Elon Musk's company, SpaceX, plans to launch an unpiloted mission in 2022 to "confirm water sources, identify hazards, and put in place initial power, mining, and life support infrastructure." In 2024, Musk wants SpaceX to send a crewed spacecraft to Mars with the primary objectives of "building a propellant depot and preparing for future crew flights," though SpaceX is quick to label these goals "aspirational."

7. China Launches a Third Space Station (2022) China now plans to begin fully operating its third space station by 2022, to put astronauts in a lunar base by later in that decade, and to send probes to Mars, including ones that could return samples of the Martian surface back to Earth. Though the moon is hardly untrodden ground after decades of exploration, a new landing is far more than just a propaganda coup, experts say. The crater where the Chinese landed is the oldest and deepest on the moon, so the probe’s discoveries may offer insights into the moon’s origins and evolution. And some scientists suspect that the surrounding basin may be rich in minerals. If exploiting the moon’s resources is the next step in space development, a successful mission could leave the Chinese better positioned. “This is a major achievement technically and symbolically,” said NamrataGoswami, an independent analyst who wrote about space for the Defense Department’s Minerva Research Institute. “China views this landing as just a steppingstone, as it also views its future manned lunar landing, since its long-term goal is to colonize the moon and use it as a vast supply of energy.” China’s Chang’e-4 became the first spacecraft to make a soft landing on the far side of the moon. Project 921 Phase 3 Crew 2–3 Launch ~2020–2022 Mass 66,000 kg Length ~ 20.00 m Diameter ~ 3.00 m

8. OSIRIS-REx's Asteroid Sample Return (2023) The OSIRIS-REx mission, which launched in 2016 to visit the asteroid Bennu, is expected to return a 2.1 ounce sample of the rocky body back to Earth by 2023. The spacecraft reached Bennu in Nov., 2018, and returned a number of stunning images of the asteroid. NASA's Artemis Mission To The Moon (2024) NASA announced that they plan to send the first woman and the next man back to the Moon by 2024. The Artemis mission will take astronauts to the Lunar South Pole to learn more about the availability of resources such as water and test vital technology that will prove useful during future missions to Mars. Another goal will be to, well, see how the human body endures long term space missions. The U.S. Habitat Arrives at the Lunar Gateway (2025) NASA's Gateway, a cis-lunar orbital space station in conjunction with other international partners, will be an ongoing project throughout the 2020s. The U.S. habitat will delivered to the space station in around 2025. Current designs allow for four astronauts onboard the space station at the same time

9. Fast-forward to Interstellar Imagine spacecraft that is expected to move at relativistic speeds. One needs to consider relativistic equations to analyze its projected path and dynamics. The relationship between proper acceleration (felt in cabin of spacecraft), , and acceleration, , of space craft in some imaginary inertial frame is with being the speed of spacecraft in inertial frame. Hence if for some reason one requires then or normalized with speed of light

10. Now, the location of spacecraft Or normalized with light year Finally, the time in cabin of spacecraft can be expressed as

13. Future propulsion Imagine matter-antimatter drive. With high energy pair of particles annihilating and forming two high energy photons. If pair energy in spacecraft rest frame is with being the rest mass of each particle and the ‘boost” factor, then (imagine spherically symmetric distribution of radiated photons, for simplicity) average momentum transfer onto spacecraft is If there are N these processes each second, then generated thrust is equal to and mass of fuel used each second is

14. The thrust generated in spacecraft rest frame (assuming g acceleration) is Solving for gives differential equation And mass of spacecraft will vary (in the spacecraft rest frame) as

15. Clearly larger corresponds to less mass loss. In case of electron-positron pair factor b=20 above corresponds to ~10 MeV particles (i.e. each particle would be initially accelerated through 10MV before collision.)