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A Digital Supplement to Insights Astronomy Magazine © 2018 Kalmbach Media Mysterious BepiColumbo Heads for the World of and Fire

Dcember 2018 • Astronomy.com to a world

Color explodes from Mercury’s surface in this enhanced-color mosaic taken through several filters. The and orange hues signify relatively young likely formed when fluid erupted from volcanoes. Medium- and dark-blue regions are older terrain, while the -blue and white streaks represent fresh material excavated from relatively recent impacts. ALL IMAGES, UNLESS OTHERWISE NOTED: NASA/JHUAPL/CIW

2 ASTRONOMY INSIGHTS • DECEMBER 2018 A world of both fire and ice, Mercury excites and confounds . The BepiColombo probe aims to make sense of this mysterious world. by Ben Evans

of extremesWWW.ASTRONOMY.COM 3 Mercury is a of contrasts. The ’s smallest boasts the largest core relative to its . at noon can soar as high as 800 degrees Fahrenheit (425 degrees Celsius) — hot enough to melt lead — but dip as low as –290 F (–180 C) before . Mercury resides nearest the , and it has the most eccentric . At its closest, the planet lies only 29 mil- lion miles (46 million kilometers) from the Sun — less than one-third ’s distance — but swings out as far as 43 million miles (70 million km). Its rapid movement across our earned it a reputation among ancient skywatchers as the fleet-footed of the gods: Italian Giuseppe “Bepi” Colombo helped develop a technique for sending a space to the Greeks and Mercury to the Romans. probe to Mercury and having it execute multiple Even though Mercury lies tantalizingly close to flybys. The honored Earth, it is frustratingly hard to get to. Only two space- his contributions by naming the BepiColombo after him. ESA craft have ever visited this barren world. But that is set to change October 19, when the international BepiColombo spacecraft begins a decade-long odyssey Before the Space Age, telescopic observa- to unlock the secrets of a planet that seems to defy tions indicated that Mercury was tidally common sense. locked to the Sun, rotating once for each The mission’s namesake — Italian scientist, math- 88- orbit and thus perpetually show- ematician, and engineer Giuseppe “Bepi” Colombo ing the same hemisphere to its parent (1920–1984) — was instrumental in devising a means to . But in the 1960s, measure- deliver a spacecraft from Earth, via , to Mercury. ments pegged its actual at Scientists already knew that a planet’s gravitational field 58.6 days, two-thirds of its . could bend the trajectory of a passing spacecraft and In essence, the planet spins about its axis enable it to rendezvous with another celestial body. In three for every two solar . the early 1970s, Colombo showed that if a spacecraft As Colombo first described, this encountered Mercury, it would end up with a period means a day on Mercury lasts twice as almost twice that of the planet’s orbital long as its . Day and each last period. He suggested that a pre- a mercurian year apiece, with new Mcisely targeted flyby would sunrises arriving every 176 days present a possibility for — the same as the six-month an economical second interval between Mariner encounter. 10 flybys. So, the Sun NASA confirmed illuminated the same the idea and used it to hemisphere of send the Mercury during all spacecraft past the three encounters, innermost planet and the spacecraft three times. The was able to map only probe encountered about 45 percent of Mercury in the planet’s surface. 1974, September 1974, and March 1975. Its photographs gave Although Mercury appears humanity its first close-up mostly gray to the eye, scientists often enhance the colors views of the world, and the in images to heighten differences in last ones we would see for chemical, physical, and mineralogical a generation. properties among surface rocks. The circular tan feature at upper right is the giant Caloris Sadly, Mariner 10 provided only a partial view Basin. The center of this hemispheric view lies because of a quirk in Mercury’s orbital parameters. at 0° latitude and 140° .

4 ASTRONOMY INSIGHTS • DECEMBER 2018 Upper left: Explosive eruptions driven by superheated volcanic gases left behind these bright yellow deposits in Mercury’s . This cluster of volcanic vents ranks among the largest on Mercury.

Lower left: When planetary scientists first saw this oddly bumpy and grooved landscape, they informally dubbed it “weird terrain.” The region formed when seismic from the mammoth impact that created the Caloris Basin converged on the planet’s opposite side.

Right: Bright blue depressions litter the floor and mountain peaks in the Raditladi impact basin. These shallow “” typically have smooth floors unmarked by impact craters, suggesting that they are among Mercury’s youngest features. Scientists created this five-image mosaic by merging high-resolution -and-white photos with a lower-resolution image in enhanced color.

A STRANGE, OLD WORLD craters that occur in chains and Mariner 10 revealed an ancient terrain of clusters, covering the highlands. rugged highlands and smooth lowlands, In contrast, the sparsely cratered strikingly reminiscent of our . Yet lowlands formed near the end of the the similarities aren’t even skin deep. , about Mercury’s craters differ markedly from 3.8 billion ago. Mariner 10 data lunar ones, because their impact ejecta suggested that the lowlands formed blankets a smaller area, partly due to either from volcanic activity or from the the planet’s much stronger . The molten material splashed onto the sur- highland regions are less saturated with face after large impacts. Although the craters; instead they are mixed with roll- spacecraft found no obvious smoking ing “intercrater plains” that constitute gun for — such as one of the oldest-known surfaces on the flows, volcanic domes, or volcanic terrestrial . cones — it did uncover strong cir- The plains were laid down some cumstantial evidence. 4.2 ago during the Late Mariner 10’s successor, NASA’s Heavy Bombardment, when remnants MESSENGER spacecraft, provided the from the solar system’s birth rained proof. During its initial flyby in January down on the infant planets. Mercury was 2008, the probe revealed a fractured only a few hundred million years old, region of ridges and furrows within the and the plains obliterated older craters, huge Caloris Basin. MESSENGER would buried several large basins, and carved go on to fly past Mercury twice more, in many of the pits and bowls seen today. October 2008 and September 2009, and The plains boast groups of secondary then orbit the inner world for four years

WWW.ASTRONOMY.COM 5 The raven-colored rim of Crater stands out from the smooth volcanic plains inside Caloris Basin. Note the hundreds of tiny blue-white hollows that dot the rim of this 48-mile-wide (77 km) crater.

As Mercury’s interior cooled, the planet’s radius shrank by up to 4 miles (7 km). The contraction buckled the surface and left behind steep cliffs, including Carnegie , seen here cutting through starting in March 2011. While in orbit, Crater. The colors in this perspective view highlight elevation changes, with red indicating the highest terrain and blue the lowest. the spacecraft discovered at least nine overlapping volcanic vents, each up to 5 miles (8 km) across and a billion years old, near Caloris’ southwestern rim. Mercury Planetary Orbiter Elsewhere on Mercury, MESSENGER MPO’s 11 instruments, some of which have uncovered residue from more than multiple components, include cameras, an 50 ancient pyroclastic flows — violent altimeter, a , a particle analyzer, Instruments inside and several . It will concentrate outbursts of hot rock and gas — tracing SIMBIO-SYS the spacecraft: back to low-profile shield volcanoes, () mainly onISA Mercury’s surface and . (SeeMORE text on p. 26 for instrument mainly within impact craters. descriptions.)MGNS ASTRONOMY: ROEN KELLY, AFTER ESA Caloris itself is an impressive relic from Mercury’s tumultuous early days. SERENA The Sun illuminated only half the basin during Mariner 10’s visits, so it was left to MESSENGER to fully reveal its struc- ture. Caloris spans 960 miles (1,550 km), MIXS placing it among the largest impact fea- MERTIS tures in the solar system, and it is ringed by a forbidding chain of mountains that SERENA SIMBIO-SYS rises 1.2 miles (2 km) above the sur- (high-resolution BELA camera) roundings. Beyond its walls, ejecta radi- SIMBIO-SYS Instruments inside ( camera) SIMBIO-SYS the spacecraft: ate in meandering ridges and grooves for (spectrometer) ISA more than 600 miles (1,000 km). The MORE MGNS impact that created Caloris was so glob- ally cataclysmic that strong seismic waves SERENA pulsed through Mercury’s interior and MPO-MAG fragmented the landscape on the planet’s SIXS opposite side, leaving a region of jumbled rocks, hills, and furrows that some scien- tists have dubbed “weird terrain.” MIXS Despite Caloris’ huge dimensions, MERTIS Mercury itself is quite small — just SERENA 3,032 miles (4,879 km) in diameter. The SIMBIO-SYS (high-resolution BELA PHEBUS planet’s small size and high camera) SIMBIO-SYS (stereo camera) led mid-20th-century to

6 ASTRONOMY INSIGHTS • DECEMBER 2018

MPO-MAG SIXS

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Deluxe Handheld ThermoTorch 10 Digital Microscope Brave winter with this Stream and save images of your 3-in-1 USB charger, flashlight, CELESTRON PREMIER SELECT DEALERS specimens to your computer via USB. and electric handwarmer. B&H Photo – 800.947.9970 – bhphotovideo.com Astronomics – 800.422.7876 – astronomics.com Adorama – 800.223.2500 – adorama.com High Point Scientific – 800.266.9590 – highpointscientific.com OPT – 800.483.6287 – optcorp.com Focus Camera – 800.221.0828 – focuscamera.com Planet – 800.504.5897 – opticsplanet.com Woodland Hills – 888.427.8766 – telescopes.net suspect it could not retain an atmo- sphere. But Mercury is full of surprises. Mariner 10 discovered a thin layer of loosely bound , known as an exo- sphere, albeit with a surface pressure tril- lions of times less than that at sea level on Earth. It contains and atoms captured from the — the stream of charged particles emanat- ing from the Sun — together with atoms liberated from the surface by impacts. Spectroscopic observations also revealed , potas- sium, , , and . Caloris and the weird terrain appear to be key sources of sodium and , indicating that impacts can release gases from below the surface. DIGGING DEEPER Farther down, the planet’s interior remains a puzzle. Before Mariner 10, scientists assumed Mercury had a solid interior that produced no intrinsic mag- netic field. They did realize, however, that the planet has an inordinately high . Overall, Mercury’s density aver- ages 5.4 times that of , close to those of the much larger Earth (5.5 times water) and Venus (5.2 times water). But the gravity of these bigger worlds crushes their interiors to far higher than they would have otherwise. Caloris Basin spans about 960 miles (1,550 kilometers) and ranks among the oldest and largest impact features in the solar system. Lava eventually flooded the floor to a depth of about 1.6 to 2.2 miles The only reasonable way to explain (2.5 to 3.5 km). The lava appears orange in this enhanced-color mosaic; more recent impact craters Mercury’s high density is with the pres- exposed darker material (blue) from below. ence of heavy elements — some 70 per- cent and nickel overall — with most of them concentrated in the planet’s giant the planet. A solid, slowly rotating planet gravity, which raises tides as the planet core. This makes Mercury by far the shouldn’t be able to generate the strong follows its eccentric orbit, could flex the most iron-rich planet in the solar system. internal dynamo needed to create an interior and play a contributing role. Scientists think the winding cliffs that intrinsic field, even one that’s just 1 per- Despite this internal heat and the reach up to a mile high and run for cent as strong as Earth’s. MESSENGER blazing Sun above, Mercury also appears hundreds of miles formed when the showed the field is offset along the rota- to be a land of ice. In the , ground- surface buckled as the interior cooled tional axis by 20 percent of Mercury’s based radar observations revealed a and contracted. Despite this shrinkage, radius and suggested that the planet pos- number of bright spots within 6.5° of MESSENGER revealed that Mercury’s sesses a partially molten outer core that the planet’s north and south . Many core stretches to within 250 miles surrounds a solid inner core. scientists interpreted these findings as (400 km) of its surface. Astronomers still aren’t sure what evidence for ice deposits on the floors Scientists also were surprised when keeps the core in an electrically conduc- of permanently shadowed craters, where Mariner 10 discovered a tive, semi-liquid state. Perhaps it is the temperatures can drop as low as together with a small that slow decay of the radioactive elements –370 F (–225 C). In November 2012, weakly deflects the solar wind around Mercury was born with. The Sun’s MESSENGER identified up to 1 trillion

Launch: Earth flyby: First Second First Second On the road to October 19, 2018 April 6, 2020 Venus flyby: Venus flyby: Mercury flyby: Mercury flyby: October 12, 2020 August 11, 2021 October 2, 2021 June 23, 2022 Mission planners expect to launch BepiColombo as early as October 19, 2018. As long as Mercury the mission commences by November 29, subsequent dates will remain the same. tons of water ice near the poles — enough to encase Washington, D.C., in Beneath two planets’ skin Mercury a frozen block 2.5 miles (4 km) deep. Mercury’s interior differs significantly from Earth’s. The inner world’s gigantic core starts BEPICOLOMBO just 250 miles (400 kilometers) below the surface and is surrounded by a relatively thin COMES ON THE SCENE mantle and crust. Most of Earth’s volume Solid iron-sul de layer resides in its mantle. The liquid parts of both Despite Mariner 10’s and MESSENGER’s Liquid middle core incredible discoveries, scientists still have planets’ cores help generate their magnetic . ASTRONOMY: ROEN KELLY Solid inner core many questions about this enigmatic world. That’s where BepiColombo comes Earth in. The European Space Agency (ESA) initially envisioned three spacecraft for this ambitious venture: The Mercury Planetary Orbiter (MPO) and Mercury Magnetospheric Orbiter (MMO) would work in tandem to unlock Mercury’s mysteries from above, and the Mercury Crust Surface Element (MSE) would explore the Upper mantle surface. ESA planned to land the MSE Lower mantle near the day-night and have it Liquid outer core survive for about a week in the harsh Solid inner core environment. The would carry heat-flow sensors, a spectrometer, a mag- netometer, a seismometer, a soil-penetrat- ing device, and a tiny rover. Abundances Unfortunately, budget considerations (SERENA) instruments. forced ESA to abandon the lander in Meanwhile, the Solar November 2003. “The decision to cancel ele- Intensity X-Ray and the lander was a loss for the mission,” Particles Spectrometer (SIXS) says BepiColombo project scientist mental will study the role of the solar Johannes Benkhoff. “What we miss is a composi- wind in weathering the planet’s so-called ‘ground truth.’ We can do many tion, and surface surface. things remotely with our instruments, age. Together with the Mercury MPO carries two instruments to help which are already on the other spacecraft, Radiometer and Thermal understand why Mercury has so much but the measurements of a lander would Spectrometer (MERTIS), Mercury iron and what this reveals about its evo- have been used to calibrate them, and Gamma-Ray and Neutron Spectrometer lutionary . The Italian Spring that can unfortunately not be recovered.” (MGNS), and Mercury Imaging X-Ray Accelerometer (ISA) and Mercury The rest of the mission continued, Spectrometer (MIXS), they will identify Orbiter Radioscience however. ESA led the development of the key rock-forming minerals, measure (MORE) will investigate the planet’s 2,535-pound (1,150 kilograms) MPO global surface temperatures, and address global gravitational field to understand spacecraft. The probe’s 11 instruments competing of the planet’s origin the size and of the core as well as were fabricated by 35 scientific and and evolution. These tools also will search the structure of the mantle and crust. industrial teams in Switzerland, for additional ice deposits and other vola- MPO also houses one-half of the Germany, Italy, the United Kingdom, tile substances at high latitudes as well as Mercury Magnetometer (MERMAG) Russia, Finland, Sweden, Austria, provide insights into the role of that will study the magnetic field for France, and the United States. volcanism. clues to the dynamo lurking inside. The Bepi Colombo Laser Altimeter To analyze the composition, structure, MPO carries a 24.6-foot-long (BELA) and the Spectrometers and and formation of Mercury’s , (7.5 meters) solar array with integrated Imagers for MPO BepiColombo MPO provides BepiColombo’s Probing optical reflectors designed to keep the Integrated System (SIMBIO- of Hermean Exosphere by spacecraft at a temperature below 390 F SYS) will create digital terrain models to (PHEBUS) and Search for (200 C). When in orbit around Mercury, quantitatively map Mercury’s geology, Exosphere Refilling and Emitted Neutral the array must continuously rotate to

Second Third Fourth Fifth Sixth Arrival at Mercury: End of nominal End of extended Mercury flyby: Mercury flyby: Mercury flyby: Mercury flyby: Mercury flyby: December 5, 2025 mission: mission? June 23, 2022 June 20, 2023 September 5, 2024 December 2, 2024 January 5, 2025 May 1, 2027 May 1, 2028

WWW.ASTRONOMY.COM 9 MESSENGER took this mosaic in October 2008, moments after it flew past Mercury for the second . The probe captured the first image (at left) nine minutes after closest approach; subsequent images came with the probe farther away (and thus show more area) and the Sun higher in the planet’s sky. This equatorial swath spans about 1,200 miles (1,950 km).

balance MPO’s power requirements with the need to keep the probe under its red- line temperature. Meanwhile, JAPAN LENDS A HAND (MDM), to explore space dust in the plan- a radiator angled toward the planet will The mission drew more international et’s vicinity and how it weathers the mer- reflect the intense infrared collaboration when the Japan Aerospace curian surface; the Mercury coming from Mercury’s searing surface. Exploration Agency (JAXA) joined the Particle Experiment (MPPE), to scrutinize “The solar arrays will be exposed to project. JAXA devel- the planet’s magnetic field and its interac- PWI high-frequency, high-intensity ultraviolet oped the 630-pound tion with particles in the solar wind and radiation, combined with high tempera- (285 kg) MMO spacecraft. Earlier this particles coming from Mercury; and the tures, which was discovered to induce an year, the space agency renamed the craft Plasma Investigation (PWI), unexpectedly fast degradation in solar- Mio, which comes from a Japanese word to study the planet’s electric and magnetic cell performance,” explains BepiColombo meaning “waterway” or “fairway.” fields as well as look for evidence of auro- project manager Ulrich Reininghaus. Mio carries five instruments, rae and radiation belts. “This was resolved by a complex method including the second half of MERMAG. “The collaboration with our Japanese of continuous solar array steering con- Its other tools are the Mercury Sodium colleagues goes very well; we almost feel trol, in order to maintain the temperature Spectral Imager (MSASI), to as one team,” says Reininghaus. “However, always below an allowed maximum, and study the origin and extent of sodium in the two spacecraft were designed and built by a specific redesign of the solar cells.” the exosphere; the Mercury Dust Monitor totally independently, although we had to

Mio (Mercury MMO-MAG MPPE Mio’s five instruments will focus on PWI Magnetospheric MPPE Mercury’s magnetic field and the solar wind environment. Several Orbiter) of the instruments have multiple components. For example, the Mercury MPPE Plasma Particle Experiment (MPPE) MPPE has six sensors, one of which has two components. (See text above for MPPE instrument descriptions.) ASTRONOMY: ROEN KELLY, AFTER ESA

MSASI PWI MDM MMO-MAG

MPPE MPPE MPPE

PWI Left: Despite its proximity to the Sun, Mercury boasts some of the coldest spots in the solar system. The colors in this view of Mercury’s south pole show the fraction of time that specific regions lie in . The black areas are those in permanent shadow, the largest of which is the crater Chao Meng-Fu. MESSENGER found solid evidence that abundant water ice exists in this crater.

Below: This enhanced-color view shows the half of Mercury centered at 0° latitude and 320° longitude. The bright bluish rays that drape across this hemisphere stretch more than 600 miles (1,000 km) and emanate from the relatively fresh at upper right.

agree on interfaces. In the science area, we window). It hold regular joint meetings. Some of our will depart science goals can only be reached if we Earth 7,770 work closely together.” mph (12,510 2021, which The final element of the spacecraft is km/h) faster will reduce the Mercury Transport Module (MTM). than the escape BepiColombo’s It holds four British-built xenon-ion from perihelion to engines, 24 chemical thrusters, and two our planet. about the same large solar arrays that will provide elec- Although impressive distance as Mercury. trical power to keep MPO and Mio alive by many standards, this Critically, this ingenious during their seven-year journey to the speed is problematic for a use of gravitational fields Sun’s closest planet. “Solar electric pro- spacecraft heading directly into the Sun’s requires little propulsive intervention pulsion [SEP] allows very significant powerful gravitational field. In fact, the from the spacecraft. “These flybys autonomous capabilities for readjusting energy needed to get to Mercury is larger depend on the [arrangement] of the plan- the interplanetary trajectory, avoiding than it would be to reach and leave ets, and that is the reason for the long altogether large midcourse maneuvers,” the solar system. Moreover, Mercury’s duration,” says Benkhoff. “The flybys says Reininghaus. orbital velocity of 105,900 mph (170,500 provide almost half of the needed energy Although the solar electric thrusters km/h) is 60 percent greater than Earth’s, to go to Mercury. The SEP engine will be provide low thrust, they operate over a demanding a substantial velocity change used for about 50 percent of the time.” long time, delivering what scien- and correspondingly high fuel Six flybys of Mercury between tists call high impulse. In fact, the consumption. October 2021 and January 2025 will slow thrusters will accumulate the greatest To overcome these obstacles, BepiColombo’s inbound trajectory until total impulse ever achieved by a space BepiColombo initially will enter an orbit its orbit nearly matches that of the planet. mission. This posed considerable chal- similar to Earth’s, using its high- Finally, in December 2025, Mercury will lenges during preflight testing. “[We impulse, low-thrust xenon-ion engines to weakly capture the spacecraft into a resolved this through] multiple test cam- slowly decelerate against solar gravity polar orbit that comes within 420 miles paigns in different chambers and with and adjust its orbital plane. “Solar elec- (675 km) of the planet’s surface and different test articles, combined with a tric propulsion was the only option to swings out to 110,600 miles (178,000 km). sophisticated modeling approach that reach Mercury,” says Benkhoff. “In prin- This so-called weak-stability-boundary allowed us to accurately predict end- ciple, one can fly a mission to Mercury technique adds flexibility compared with of- performance of the thrusters,” with chemical propulsion, but it all traditional approaches, where a single explains Benkhoff. depends on the thrust-to- ratio. SEP engine firing typically brings a spacecraft is about eight times more efficient than into orbit. BepiColombo’s chemical GETTING THERE chemical fuel. Thus, for BepiColombo, thrusters will stabilize the orbit gradually Like Mariner 10 and MESSENGER we would have needed at least 2 tons and, after traveling 5.5 billion miles before it, BepiColombo will take a circu- more mass to accommodate this.” (8.9 billion km), the mission will at last itous route to reach Mercury. The space- The spacecraft will complete 1.5 cir- be underway. craft will launch from Kourou, French cuits of the Sun, returning to Earth in After the MTM separates from the Guiana, atop a giant Ariane 5 rocket, April 2020 to pick up a gravitational probes, Japan’s Mio will be spring-ejected perhaps as early as October 19 (the first boost. This will propel it to Venus for from its protective sunshield and part chance during a six-week launch rendezvous in October 2020 and August company with Europe’s MPO. Three Molten lava once covered Mercury’s vast northern volcanic plains. Lava nearly filled the 181-mile-wide (291 km) impact basin, which lies at the lower right of this enhanced-color image. As the lava cooled, it formed large ridges that appear particularly prominent at bottom left. Meanwhile, the bright orange region near the scene’s top shows the location of a volcanic vent that unleashed one of the planet’s largest pyroclastic flows. months later, the pair will commence will carry it as close to Mercury’s surface Both will deliver an abundance of learn- autonomous operations, the former con- as 365 miles (590 km) and as far away ing, and both will accomplish their goals trolled from the Usuda Deep Space as 7,230 miles (11,640 km) during a through ingenuity, an element of trick- Centre in Nagano, Japan, and the latter 9.3- orbit. ery, and a pinch or two of old-fashioned from the Cebreros ground station near Scientists expect the baseline mission good fortune. Madrid, Spain. “However, from the to last until May 2027, but there’s a good standpoint of science operations, coordi- chance ESA will grant a one-year exten- British writer Ben Evans authored nation planning will be maintained sion. As a bonus, BepiColombo will the multivolume History of Human Space among the principal investigators of the make precise measurements of Mercury’s Exploration, published by Springer-Praxis. two spacecraft, and a certain amount of orbital parameters. Because the planet joint observations will certainly take lies so close to the Sun, this should place,” explains Reininghaus. allow astronomers to chart our star’s All told, the two spacecraft will bring gravitational field in detail and provide a about 275 pounds (125 kg) of scientific rigorous test of ’s general instruments to bear upon one of the of relativity. least-known worlds in the solar system. Although the spacecraft’s roundabout MPO will occupy a looping, 2.3-hour orbit route to Mercury is hardly in keeping at a distance that ranges from 300 miles with the fleet-footed nature of the plan- (480 km) to 930 miles (1,500 km); Mio et’s mythological namesake, the mission will follow a highly elliptical path that and the god do share some similarities. CELESTRON PREMIER SELECT DEALERS B&H Photo – 800.947.9970 – bhphotovideo.com Astronomics – 800.422.7876 – astronomics.com Adorama – 800.223.2500 – adorama.com High Point Scientific – 800.266.9590 – highpointscientific.com OPT Telescopes – 800.483.6287 – optcorp.com Focus Camera – 800.221.0828 – focuscamera.com Optics Planet – 800.504.5897 – opticsplanet.com Woodland Hills – 888.427.8766 – telescopes.net