Perseverance Mission landing

Source: NASA/JPL-Caltech

  This week - on 18 February 2021 - NASA's Perseverance Rover  landed on Mars safely. There is so much information about this mission from many different sources that it is difficult to choose what to focus on with engineering students.

  For my students, I chose materials from NASA's own website for the mission, which has further links to different asepcts of the mission and to information about Mars. The most attention-getting part is the video of the Perseverance landing, which was recorded by several high-definition cameras located under the spacecraft. 

The video last 3:25 minutes; English subtitles of the audio embedded in the video are available.

Link to video: https://www.nasa.gov/press-release/nasa-s-mars-perseverance-rover-provides-front-row-seat-to-landing-first-audio

As indicated in the accompanying text, Thomas Zurbuchen, NASA associate administrator for science, says, "This video of Perseverance's descent is the closest you can get to landing on Mars without putting on a pressure suit." He goes on to say, "It should become mandatory viewing for young women and men who not only want to explore other worlds and build the spacecraft that will take them there, but also want to be part of the diverse teams achieving all the audacious goals in our future."

The link to the pages about the Perseverance mission: https://www.nasa.gov/perseverance

The website describes the landing and its challenges in a very clear way:

• "Entry, Descent, and Landing - often referred to as 'EDL' - is the shortest and most intense phase of the Mars 2020 mission. It begins when the spacecraft reaches the top of the Martian atmosphere, travelling nearly 12,500 miles per hour (20,000 kilometers per hour). It ends about seven minutes later, with Perseverance stationary on the Martian surface. To safely go from those speeds down to zero, in that short amount of time, while hitting a narrow target on the surface, requires 'slamming on the brakes' in a very careful, creative and challenging way."

I felt the focus on "a very careful, creative and challenging way" of solving a technical problem would be particularly relevant to my students. And the way that the writing continues sounds like a personal conversation, so it was both easy and appealing for my students to read. The lower register terms they identified are underlined:

• "Landing on Mars is hard. Only about 40 percent of the missions ever sent to Mars - by any space agency - have been successful. Hundreds of things have to go just right during this nail-biting drop. What's more, Perseverance has to handle everything by itself. During the landing, it takes more than 11 minutes to get a radio signal back from Mars, so by the time the mission team hears that the spacecraft has entered the atmosphere, in reality, the rover is already on the ground. So, Perseverance is designed to complete the entire EDL process by itself - autonomously."

The casual tone starts with a very basic sentence: Landing on Mars is hard. No scientific or technical language needed!

Since my students are generally interested in the technology created for the flight and the scientific mission, I also focused on the website page with an overview of the spacecraft:

Link: https://mars.nasa.gov/mars2020/spacecraft/overview/

There are 5 spacecraft components (also see the visual accompanying this post):

• Cruise Stage
• Backshell
• Descent Stage
• Rover
• Heat Shield

Each component is described briefly, indicating what its function is. For example, the text for Descent Stage:

• "The descent stage is the rover's free-flying 'jetpack,' which separates from the backshell and uses eight engines to slow the final descent. It also contains the landing radar system used to make last-minute decisions about touchdown. Just before touchdown, the descent stage lowers the rover on cables before gently placing it on the surface. Once the rover is on the ground, the descent stage flies off to make its own uncontrolled landing on the surface, a safe distance away from the rover."

This page has a further link to the Rover, which is the component that my students are most interested in: https://mars.nasa.gov/mars2020/spacecraft/rover/

The page downloads a 3D model of the Rover on which it's possible to zoom in, rotate, and mouse over each component to get a closer look and more information. The written information underneath the model compares the components to body parts enabling the rover to function for survival. It is a very good example of using comparisons that a non-technical audience would understand:

• "It is car-sized, about 10 feet long (not including the arm), 9 feet wide, and 7 feet tall (about 3 meters long, 2.7 meters wide, and 2.2 meters tall). But at 2,260 pounds (1,025 kilograms), it weighs less than a compact car. In some sense, the rover parts are similar to what any living creature would need to keep it 'alive' and able to explore."

This comparison is continued in the brief description of the purpose of each part:

• body: a structure that protects the rover's "vital organs"
• brains: computers to process information
• temperature controls: internal heaters, a layer of insulation, and more
• "neck and head": a mast for the cameras to give the rover a human-scale view
• eyes and ears: cameras and instruments that give the rover information about its environment
• arm and "hand": a way to extend its reach and collect rock samples for study
• wheels and legs: parts for mobility
• electrical power: batteries and power
• communications: antennas for "speaking" and "listening"

Clicking on each of the parts brings you to a separate page with more information about that particular part.

Finally, a further resource is a Landing Toolkit for educators: https://mars.nasa.gov/mars2020/timeline/landing/

Much of the information was for use before the landing, but there are many more materials, and links with ideas for how to use them.

Five unusual technologies for water

An article written by Manzoor Qadir and Vladimir Smakhtin, Assistant Director and Director, respectively, of the Institute for Water, Environment and Health, United Nations University, reports 5 possible technologies for harvesting water in water-scarce areas of the world. There isn't much specific information about the technologies themselves, but the short description of each of the technologies includes a link to a scientific paper describing that process. These are probably too academic for many students, but the abstracts and conclusions give an overview of the information.

Link to the article: https://theconversation.com/five-unusual-technologies-for-harvesting-water-in-dry-areas-154031

The 5 technologies, with part of their description from the article, are:

• Catching fog: Fog can be collected using a vertical mesh that intercepts the droplet stream. This water then runs down into a water collection, storage and distribution system.
• Cloud seeding: This technology involves dispersing small particles into clouds or in their vicinity. These particles act as a starting point for raindrops or ice crystals, promoting their formation. In turn, this makes it more likely to rain or snow.
• Minimising evaporation: There are two major types of micro-catchment rainwater harvesting systems. One is water harvesting via rooftop systems where runoff is collected and stored in tanks or similar devices. This water is used domestically or for livestock watering. The second is water harvesting for agriculture, which involves collecting the rainwater that runs off a catchment area in a small reservoir or in the root zone of a cultivated area.
• Desalinating seawater: The process of desalination removes salt from seawater or brackish groundwater to make them drinkable.
• Iceberg harvesting: Moving an iceberg across the ocean is technically possible, based on a theoretical four-part process. It would require locating a suitable source and supply, calculating the necessary towing power requirements, accurately predicting melting in transit, and estimating the economic feasibility of the entire endeavour.

Students could discuss the pros and cons of each technology, rating them according to different factors; for example: practicality, impact, economy, timeframe, region, etc.

The first sentence of the article is: "Water scarcity is among the top five global risks affecting people's wellbeing." Students could brainstorm what they think the other four global risks are. The risks are divided into two types: risks in terms of likelihood and risks in terms of impact. So students could also rate their ideas according to those factors. The sentence contains a link to the World Economic Forum Global Risk Report 2020, so their answers can be compared to the list in the report. This is from that report:

The Top 5 Global Risks in Terms of Likelihood:

• Extreme weather
• Climate action failure
• Natural disasters
• Biodiversity loss
• Human-made environmental disasters

The Top 5 Global Risks in Terms of Impact:

• Climate action failure
• Weapons of mass destruction
• Biodiversity loss
• Extreme weather
• Water crises

For the longer lists of global risks, in terms of likelihood and impact, here is the link to the entire report: http://www3.weforum.org/docs/WEF_Global_Risk_Report_2020.pdf

Since the article focuses on water issues, there is of course useful vocabulary for this field of study. The words and phrases can be focused on according to category, as I have listed them below, or noted in terms of word form (eg, noun vs verb: runoff - runs off; noun vs adjective: water scarcity - water-scarce areas).

Types of water:

• cloud water
• desalinated water
• drinking water
• droplet stream
• drought
• freshwater
• fog
• groundwater
• iceberg
• municipal water supply
• precipitation
• polar ice caps
• rainfall
• runoff
• seawater
• water embedded in fog
• water resources
• water-scarce area

Water verbs:

• absorbing (water)
• dispersing (small particles)
• evaporate
• melting
• runs off
• (resources can be) tapped

Technical terms:

• catchment
• desalination
• micro-catchment
• rain enhancement
• water cycle
• water harvesting
• water insecurity factors
• water scarcity
• water shortages

If students do further work learning about any of these technologies and want to talk or write about them, then this vocabulary will certainly come in useful.

Podcast: Why go to the moon?

In my last post (8 February: SpaceX vs Nasa to the moon), I wrote about an article comparing which rocket is most likely to get humans to the moon again. This post considers why humans want to go to the moon at all.

There is a podcast series of 5 episodes on the conversation website, called To the Moon and Beyond. Episode 4 is "What's the point of going back to the moon?" The podcast series was made in 2019, but the issues raised are still relevant.

Link to podcast 4: https://theconversation.com/to-the-moon-and-beyond-4-whats-the-point-of-going-back-to-the-moon-120791

The short article accompanying the podcast gives an overview of the topics discussed and describes the episode:

• "In the fourth episode of The Conversation's To the moon and beyond podcast, we delve into why there's a renewed drive to put humans back on the surface of the moon. What's there to go back for? And what are the practical, legal and ethical questions facing those who want to set up a base there -- and potentially start mining the moon?"

The two hosts are Miriam Frankel (Science Editor at The Conversation) and Martin Archer (Space Plasma Physicist, Queen Mary University of London). The 5 scientists they interview are:

• Frans von der Dunk, Professor of Space Law, University of Nebraska-Lincoln
• Fréderic Marin, Chargé de recherche (CNRS) à l'Observatoire Astronomique de Strasbourg, Université de Strasbourg
• Katherine Joy, Royal Society University Research Fellow/Reader, School of Earth and Environmental Sciences, University of Manchester
• Rowena Christiansen, Medical Education Tutor, Doctor and Researcher, University of Melbourne
• Tanja Masson-Zwaan, Assistant Professor of Space Law at Leiden University in The Netherlands

The podcast lasts 35:58 minues, so it might be rather long for some students. All interviewees speak clearly, but there are a variety of accents (both English and non-native speaker) and various speaking tempos. However, students could listen to the podcast at home, so they can repeat as necessary or listen in shorter time sections.

The topics discussed include:

• Which resources could potentially be found on the moon and which problems would there be with extraction;
• Which laws exist, and which should be made, that govern who can mine lunar resources and how ownership would be determined;
• The ethics involved in the abilities of different countries to travel to the moon;
• The physical and psychological effects of being in low gravity, with extremely long days and nights;
• Ways in which people could survive sustainably on the moon.

Unfortunately, there is no transcript available. If listening to the entire podcast for an assignment or task is too difficult for some groups, then the teacher could "divide" the podcast into separate sections, each one covering a different topic area. Then each student, or small groups, could be assigned a specific section to listen to and write a summary of the information, which could be made available to their colleagues. This way, each student would have an overview of the entire podcast.

If the topic of "to the moon and beyond" is interesting for the group, then students might want to choose another podcast in the series (each one is 30 to 34 minutes):

• 1: What we learned from landing on the moon and why we stopped going
• 2: How humanity reacted to the moon landing and why it led to conspiracy theories
• 3: The new space race and what winning it looks like
• 5: What space exploration will look like in 2069

Link to the series overview: https://theconversation.com/uk/podcasts/moon-and-beyond

SpaceX vs Nasa to the moon

A recent article on the website 'the conversation' compares and contrasts two rockets being developed for space travel: SpaceX vs Nasa: who will get us to the Moon first? Here's how their latest rockets compare, by Gareth Dorrian (Post Doctoral Research Fellow in Space Science, University of Birmingham) and Ian Whittaker (Senior Lecturer in Physics, Nottingham Trent University). Accompanying image is from the article.

Link to article: https://theconversation.com/spacex-vs-nasa-who-will-get-us-to-the-moon-first-heres-how-their-latest-rockets-compare-154199

The first part of the article gives background information about rockets, and then describes first the SpaceX Starship and then Nasa's Space Launch System (SLS). From this information, students could look into the relative advantages and disadvantages further. For example, SpaceX's launch vehicle burns a combination of liquid methane and liquid oxygen, while NASA's SLS core stage contains liquid hydrogen and liquid oxyen.

"The [SpaceX launch vehicle's] rocket will provide 15 million pounds of thrust at launch" vs. Nasa: "The core stage of the rocket is augmented by two solid rocket boosters, attached to its sides, providing a total combined thrust of 8.2 million pounds at launch."

The final paragraph sums up the pros and cons of each:

"Ultimately it is a competition between an agency that has had years of testing and experience but is limited by a fluctuating taxpayer budget and administration policy changes, and a company relatively new to the game but which has already launched 109 Falcon 9 rockets with a 98% success rate and has a dedicated long-term cash flow."

Students could first compare their first impressions of the two approaches, and then gather information to support one or the other. In a classroom setting, a debate could be organized (SpaceX or Nasa?). In a distance-learning situation, students could submit their "argument" supporting the one they think will be the 'winner' and why. Fellow students with an opposing view could choose one to read and comment on.

Throughout the semester, students can follow updates about the two rockets since both SpaceX and Nasa are often in the news and on many scientific/technical websites. Areas to focus on are not only each rocket's advantages and disadvantages, but also the differences in innovation development between a private firm and a government agency.

The article has relevant examples of language used to compare and contrast. For example:

• but X is also
• both X and Y are developing
• which is approximately twice as much as
• X and Y are both
• their main difference from X is that
• about 5% more than
• which is smaller and lighter than
• a task that current Xs are currently not capable of performing
• so there is a higher cost with X, both in materials and environmentally
• which is potentially more than
• whereas

There are also examples of the tenses that my students find most difficult to use.

Examples of the present perfect tense (which has no reference to a point of time in the past):

• No-one has visited the Moon since 1972.
• Nasa has selected the private company SpaceX to be part of its commercial spaceflight operations
• Musk has also stated that a crewed Martian mission could take place as early as 2024
• Ultimately it is a competition between an agency that has had years of testing and experience
• a company relatively new to the game but which has already launched 109 Falcon 9 rockets

Contrasted with simple past tense, with related past time reference underlined:

• A recent test flight of the Starship prototype, the SN8, successfully demonstrated ... Unfortunately there was a malfunction in one of the Raptor engines and the SN8 crashed on landing.
• three of which were used on the previous Space Shuttle
• a test fire of the SLS core stage was stopped a minute into the eight-minute test

There are many examples of the use of the simple present tense to indicate "something that is true in the present; that happens regularly in the present; that is always true" (according to the British Council website https://learnenglish.britishcouncil.org/english-grammar-reference/present-simple) -- Rockets go through multiple stages to get into orbit; the rocket becomes lighter; the Starship flips into a vertical position and uses its on-board Raptor engines; etc.

But my students find it more difficult to decide when to use the present progressive tense. So the examples from the article are very useful as illustrations of something happening currently:

• the firm is also pursuing its own space exploration agenda
• both Nasa and SpaceX are developing new heavy lift rockets
• The spacecraft is maturing rapidly
• a task that current Nasa rockets are currently not capable of performing
• "I don't think we're looking at a significant design change."
• they are running #dearMoon - a project involving lunar space tourism

Finally, since the article includes information about planned future developments, there is the use of the future tense with "will": SpaceX's launch system will be comprised of two stages; the rocket will provide; it will have sufficient thrust; this will lift the spacecraft; etc. But the future is also referred to with the simple present tense and with phrases useful for students to learn:

• The upper stage is intended to lift the attached payload
• The core stage and booster rockets are unlikely to be reusable
• It is designed to evolve to larger stages
• which is potentially more than Starship
• Artemis 2 is planned as the first crewed mission
• and is expected to launch in August 2023
• a crewed Martian mission could take place as early as 2024

The article ends with the sentence: "Whoever reaches the Moon first will inaugurate a new era of exploration of a world which still has much scientific value." This alone could provide much discussion or response: Who is likely to "reach the Moon first"; what the impact could be of "who" the first would be; what a "new era" would look like; what aspects of "exploration" would be the most useful or least harmful; and what examples of "scientific value" would be generated.

Bonus: The article's website has a 2:21-minute film clip of the Starship SN8 High-altitude flight re-cap. There is no narration except for the voice counting liftoff, but the stages are labeled on the screen. There is also a labeled diagram of the stages of Nasa's SLS as well as the illustration comparing rockets that I have used for this post.