Vega 2

Key takeaways

Vega 2 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Vega 2 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Vega 2 from memory before moving on to harder problems.

Reference excerpt

Vega 2 (along with Vega 1) was a Soviet space probe part of the Vega program to explore Halley's Comet and Venus. The spacecraft was a development of the earlier Venera craft. The name VeGa (ВеГа) combines the first two letters of the Russian words for Venus (Венера: "Venera") and Halley (Галлея: "Galleya"). They were designed by Babakin Space Centre and constructed as 5VK by Lavochkin at Khimki. The craft was powered by large twin solar panels. Instruments included an antenna dish, cameras, spectrometer, infrared sounder, magnetometers (MISCHA) and plasma probes. The 4,840-kilogram (10,670 lb) craft was launched on top of a Proton-K from Baikonur Cosmodrome, Tyuratam, Kazakh SSR. Both Vega 1 and 2 were three-axis stabilized spacecraft. The spacecraft were equipped with a dual bumper shield for dust protection from Halley's Comet.

Venus mission The descent module arrived at Venus on 15 June 1985, two days after being released from the Vega 2 flyby probe. The module, a 1,500-kilogram (3,300 lb), 240-centimetre-diameter (7.9 ft) sphere, contained a surface lander and a balloon explorer. The flyby probe performed a gravitational assist maneuver using Venus, and continued its mission to intercept the comet.

Lander The surface lander was identical to that of Vega 1 as well as the previous six Venera missions. The objective of the probe was the study of the atmosphere and the exposed surface of the planet. The scientific payload included a UV spectrometer, temperature and pressure sensors, a water concentration meter, a gas-phase chromatograph, an X-ray spectrometer, a mass spectrometer, and a surface sampling device. Several of these scientific tools (the UV spectrometer, the mass spectrograph, and the devices to measure pressure and temperature) were developed in collaboration with French scientists. Since the probe made a nighttime landing, no images were taken. The Vega 2 lander touched down at 03:00:50 UT on 15 June 1985 at around 7.14°S 177.67°E / -7.14; 177.67, in the northern region of Aphrodite Terra called Rusalka Planitia. The altitude of the touchdown site was 0.1 kilometres (330 ft) above the planetary mean radius. The measured pressure at the landing site was 91 atm and the temperature was 736 K (463 °C; 865 °F). The surface sample was found to be an anorthosite–troctolite rock, rarely found on Earth, but present in the lunar highlands, leading to the conclusion that the area was probably the oldest explored by any Venera vehicle. It transmitted data from the surface for 56 minutes.

Balloon

The Vega 2 Lander/Balloon capsule entered the Venusian atmosphere (125 kilometres [78 mi] altitude) at 02:06:04 UT (Earth received time; Moscow time 05:06:04) on 15 June 1985 at roughly 11 kilometres per second (6.8 mi/s). At approximately 2:06:19 UT the parachute attached to the landing craft cap opened at an altitude of 64 kilometres (40 mi). The cap and parachute were released 15 seconds later at 63 kilometres (39 mi) altitude. The balloon package was pulled out of its compartment by parachute 40 seconds later at 61 kilometres (38 mi) altitude, at 7.45°S, 179.8°E. A second parachute opened at an altitude of 55 kilometres (34 mi), 200 seconds after entry, extracting the furled balloon. The balloon was inflated 100 seconds later at 54 kilometres (34 mi) and the parachute and inflation system were jettisoned. The ballast was jettisoned when the balloon reached roughly 50 kilometres (31 mi) and the balloon floated back to a stable height between 53 and 54 kilometres (33 and 34 mi) some 15 to 25 minutes after entry. The mean stable height was 53.6 kilometres (33.3 mi), with a pressure of 535 millibars (535 hPa) and a temperature of 308–316 K (35–43 °C; 95–109 °F) in the middle, most active layer of the Venus three-tiered cloud system. The balloon drifted westward in the zonal wind flow with an average speed of about 66 metres per second (220 ft/s) at nearly constant latitude. The probe crossed the terminator from night to day at 9:10 UT on 16 June after traversing 7,400 kilometres (4,600 mi). The probe continued to operate in the daytime until the final transmission was received at 00:38 UT on 17 June from 7.5 S, 76.3 E after a total traverse distance of 11,100 kilometres (6,900 mi), about 29% of the planet's circumference. It is not known how much further the balloon traveled after the final communication.

Halley mission After their encounters, the Vegas' motherships were redirected by Venus's gravity to intercept Halley's Comet. The spacecraft initiated its encounter on March 7, 1986, by taking 100 photos of the comet from a distance of 14,000,000 kilometres (8,700,000 mi). Vega 2 made its closest approach at 07:20 UT on March 9, 1986, at 8,030 kilometres (4,990 mi). The data intensive examination of the comet covered only the three hours around closest approach. They were intended to measure the physical parameters of the nucleus, such as dimensions, shape, temperature and surface properties, as well as to study the structure and dynamics of the coma, the gas composition close to the nucleus, the dust particles' composition and mass distribution as functions of distance to the nucleus and the cometary-solar wind interaction. During the encounter, Vega 2 took 700 images of the comet, with better resolution than those from the twin Vega 1, partly due to the presence of less dust outside the coma at the time. Yet Vega 2 recorded an 80% power loss during the encounter as compared to Vega 1's 40%. After further imaging sessions on 10 and 11 March 1986, Vega 2 finished its primary mission.

Post Halley A 6 million kilometer distant flyby of 2101 Adonis was considered, however, Vega 2 didn't have enough fuel left to make the necessary orbital changes for the flyby. Instead the Vega probes took the opportunity to measure the dust as they passed through the orbits of 72P/Denning–Fujikawa, Biela's Comet and 289P/Blanpain. Contact with Vega 2 was lost on 24 March 1987. Vega 1 had previously exhausted its attitude control propellant on 30 January 1987. Vega 2 is currently in heliocentric orbit, with perihelion of 0.70 AU, aphelion of 0.98 AU, eccentricity of 0.17, inclination of 2.3 degrees and orbital period of 281 days.

Illustrations

Worked examples

Example 1 — a first encounter with Vega 2

Start with the simplest possible case. Write down what Vega 2 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Vega 2 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Vega 2 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Vega 2

In research: Vega 2 appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Vega 2 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Vega 2 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1984 in spaceflight, 1984 in the Soviet Union, Aphrodite Terra quadrangle, so understanding it makes those chapters shorter.
In everyday life: Look for Vega 2 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Vega 2 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Vega 2 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Vega 2 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Vega 2 in simple terms?

Vega 2 (along with Vega 1) was a Soviet space probe part of the Vega program to explore Halley's Comet and Venus. The spacecraft was a development of the earlier Venera craft.

Why does Vega 2 matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Vega 2?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Vega 2.