It seems like space is in the air this week: there is a Cloud City at the Met and a mission to Mars at the Armory. Not that there aren't other things to do. The International Center of Photography unveils a show dedicated to the transsexual streetwalkers of Paris from the 1950s and Brent Green meditates on fate over at Andrew Edlin. Here's what we're looking at:

Tomás Saraceno on the Roof: Cloud City at the Metropolitan Museum of Art Okay, so it’s not the Cloud City from Empire Strikes Back. (Bummer.) But Tomás Saraceño’s space-age sculpture is nonetheless pretty darn otherworldly: a giant stacked arrangement of three-dimensional polygonal forms that seems to bubble up from the roof of the Met. The piece is made up of mirrored and transparent surfaces intended to scramble a viewer’s sense of direction: look at your feet and you might see the sky, look towards the sky, and you might be greeted by a view of the ground. It is possible to climb the sculpture’s various levels, all the way to an overhanging bubble with a clear plastic floor (dizzying). But be forewarned: Cloud City has clear and mirrored floors, which means you’ll be showing off your choners to the world if you decide to wear a skirt. Through November 4, on the Upper East Side.

Christer Strömholm: Les Amies de Place Blanche at the International Center of Photography In the 1950s and early 1960s, France was experiencing an ultra-conservative pendulum swing. Charles de Gaulle reintroduced laws that allowed the state to seize the properties of landlords who allowed prostitution on their premises. Transvestites were regularly harassed by police, arrested for being “dressed as women outside the period of carnival.” In this climate, the Swedish-born Strömholm moved to Paris and began photographing the transsexual prostitutes who frequented the Place Blanche (where the Moulin Rouge is located). He photographed them on the streets, in their hotel rooms and in bars for roughly a decade — becoming a trusted friend in the process. It shows: the photographer’s stark black-and-white images (which recall the work of Brassaï) record moments of glamor, intimacy and heartbreak -- a revealing look at a group relegated to the fringes of French society. Opens Friday, in Midtown.

Brent Green, To Many Men Strange Fates Are Given, at Andrew Edlin This curious little show is an unusual mix of the down-home and the high-tech. A crude animated short can only be seen through a scrim of polarized-film or via specially-made glasses that employ the same material. (Otherwise, all you see is a blank screen.) But don the glasses and an array of jagged drawings comes to life on the screen as a narrator recites a spoken-word piece that touches on the idea of destiny. It may sound insufferably lofty, but it feels earthy-real. Set to scratchy guitar music, the artist’s gravelly voice rambles poetically about the Russian woman asked to sew a spacesuit for a small dog in the 1950s — an unnamed, unheralded individual who had a hand in an unlikely historic event. Through June 23, at Andrew Edlin Gallery, in Chelsea.

Tom Sachs, Space Program: Mars, at the Park Avenue Armory. Using humble materials such as plastic, wood and the occasional umbrella, Sachs has built a set for a fictional Mars mission that includes a control wall of TV monitors as well as a scale replica of a NASA Landing Excursion Module (an LEM, like the ones that landed on the moon). With the cavernous darkness of the Armory Drill Hall serving as a fill-in for the icy blackness of space, Sachs has set up various stations related to a Mars Mission. At some of these, assistants (outfitted in matching Banana Republic-style ensembles) recreate blast-offs on miniaturized sets. At others, visitors can admire the details of Sachs’ bricolage craftsmanship: NASA logos crafted from wood, a suitcase-turned-aeronautical toolbox and a Mars rover put together out of lawn chairs and a hacked golf cart. The biggest piece, the LEM, is one of the most impressive — but can only be entered once you’ve completed an “indoctrination” which includes watching an hour's worth of films. Good luck getting in. (Tip: You can watch them online in advance.) The set-up is cute (if not totally original), but the premise wears thin after visits to four or five stations. Perhaps the best way to see the work will be at one of the live performances -- when Sachs' team demonstrates the 'Flight Plan,' putting all of the sculptural pieces into play. Opens on Wednesday, on the Upper East Side. See the website for performance details.