IELTS Listening 實戰 26 太空探索演講（Part 4 風格）

Good morning. Today's lecture surveys the history and present state of human and robotic space exploration, organised into four eras, followed by three challenges shaping the next decade. By the end you should be able to place any major mission in its era and explain the principal barriers facing crewed deep-space travel.

Let's begin with the first era — superpower competition, 1957 to 1975. This is the period of the so-called Space Race between the United States and the Soviet Union. It opens with Sputnik 1 in October 1957 — the first artificial satellite, a Soviet launch that took the West by surprise. Twelve years later, in July 1969, Apollo 11 placed the first humans on the Moon. The era closes with the Apollo-Soyuz test project in 1975 — the first cooperative docking between American and Soviet crews, symbolically ending the race.

The second era — orbital infrastructure, 1981 to 2011 — focuses on reusable launch and long-duration habitats. The Space Shuttle programme ran from 1981 to 2011, completing 135 missions despite two catastrophic accidents. Construction of the International Space Station, ISS, began in 1998 and is ongoing — it has now been continuously occupied for over twenty-three years. The ISS is the largest international engineering project in history, involving fifteen nations.

The third era — robotic exploration of the solar system, 1990 to 2010s — saw spacecraft reach every planet. The Hubble Space Telescope, launched 1990, transformed astronomy by imaging objects up to thirteen billion light-years away. Cassini-Huygens, 1997 to 2017, orbited Saturn and dropped a probe onto its moon Titan. Mars Curiosity Rover, landed 2012, is still operating after exceeding its planned two-year mission by more than a decade. And New Horizons, launched 2006, flew past Pluto in 2015, returning the first close-up images of the dwarf planet.

The fourth and current era — commercial-led human spaceflight, 2010 to present. The defining shift is that private companies now lead launch services. SpaceX, founded by Elon Musk in 2002, achieved the first orbital-class rocket landing in 2015 — making rockets reusable for the first time. Blue Origin and Rocket Lab followed similar trajectories. NASA's role has shifted from prime contractor to customer — purchasing seats and cargo capacity rather than building everything in-house. The current flagship programme, Artemis, plans to return humans to the Moon by 2026 and aims for a sustainable lunar base by 2030.

Now, three challenges shaping the next decade.

The first is radiation. Astronauts on a Mars mission would receive cumulative radiation doses far exceeding Earth limits. Solutions include better shielding, faster propulsion to shorten exposure, and pharmacological countermeasures — all under active research.

The second is propulsion. Conventional chemical rockets take roughly seven months to reach Mars. Nuclear thermal propulsion, currently being prototyped, could halve that to about three and a half months. Faster transit reduces radiation, food, and psychological strain — but nuclear propulsion raises regulatory and political concerns.

The third is economics. The Apollo programme cost roughly twenty-five billion dollars in 1960s money — about two hundred and fifty billion in today's terms. Reusability has cut launch costs by around ninety percent in the past decade. Even so, a crewed Mars mission is currently estimated at one trillion dollars over twenty years — comparable to a major military programme.

In conclusion, the historical pattern is clear: each era has been driven by a different mix of competition, cooperation, and commerce. The next era will be defined by whether the deep-space barriers — radiation, propulsion, cost — yield to focused investment, or remain as decisive limits. Next week we'll examine the case for and against permanent settlement on Mars. Please read chapter eight.

Questions 1-6 — Complete the lecture notes. Write NO MORE THAN TWO WORDS AND/OR A NUMBER.

Four Eras of Space Exploration

Era 1 — Superpower competition (1957-1975)

• Opens with Sputnik 1, launched in (1) _______ 1957
• Closes with the Apollo-Soyuz (2) _______ project in 1975

Era 2 — Orbital infrastructure (1981-2011)

• ISS continuously occupied for over (3) _______ years
• ISS involves (4) _______ nations

Era 3 — Robotic exploration

• Hubble images objects up to (5) _______ billion light-years away
• Mars Curiosity Rover landed in (6) _______

Questions 7-10 — Complete the summary. Write NO MORE THAN TWO WORDS.

The current commercial era began around 2010. SpaceX achieved the first reusable orbital-class rocket landing in 2015, and NASA has shifted from prime contractor to the role of (7) _______. The Artemis programme aims for a sustainable (8) _______ base by 2030. Three barriers face deep-space crewed missions: (9) _______, propulsion, and economics. Reusability has cut launch costs by approximately (10) _______ % in the past decade.