Posts Tagged ‘mars phoenix’

“Cellophane Telescope” by Seymour Sun

Wednesday, October 3rd, 2012

The payload deployment test shown above moves the FalconSAT-7 mission forward, which is scheduled for 2015. Why is this “cubesat” important? It uses diffraction instead of refraction or reflection and it is becoming a real alternate to a large space-based observatory in studying the Sun’s chromosphere — especially in the H-alpha wavelengths.

The cubesat is being developed by the U.S. Air Force Academy and NASA’s Goddard Space Flight Center, among others, including the NRO, DARPA, AFOSR, AFIT, MMA Design and AFRL.

A photon sieve is a novel optical element consisting of a flat opaque sheet with millions of tiny holes. Light passing through these holes is focused in a similar manner to a lens or a mirror. Photon sieves have several key advantages over those more conventional optics:

  • Focusing can be achieved from a flat, thin sheet that can be unfurled from a very compact, lightweight package
  • Surface quality tolerances are orders of magnitude more relaxed
  • The fabrication costs are much lower

The trade-offs include:

  • Lower efficiency / loss of light
  • Narrow bandwidth giving what are essentially grayscale images

The photon sieve will have the following design parameters:

  • 200mm diameter, 400mm focal length, 656.3nm wavelength
  • 2.5 billion holes ranging in size from 2-277 microns
  • 50% fill factor, 30% focusing efficiency

The telescope has a relatively simple design due to space constraints and has:

  • 4 µrad resolution which equates to 600 km at Sun surface
  • ~0.1 degree field of view (about a 1/5th of the Sun’s disk)

Clockwise from top left: A 4-inch photon sieve lit by laser light. The focal spot produced. A magnified image of the central 25mm. An image of a resolution chart produced by the sieve. An interferogram of the wavefront that indicates perfect focusing capability.

It’s Alive!

Monday, June 27th, 2011

Thank you, doctor. Nice piece by Jeremey Hsu at, calling the new Mars exploration spacecraft “Frankenstein” for all the money-saving shortcuts on the build side…

Take the DNA of the deceased NASA Phoenix Mars Lander, add bits and pieces from several lost Mars missions and you have a “Frankenstein” mission competing for a spot on NASA’s space exploration lineup for the next decade.

The mission, once called the Geophysical Monitoring Station, is nameless for now. It would carry a seismometer that flew aboard a doomed Mars Surveyor 98 spacecraft, and a burrowing “mole” device based on an instrument lost during the British Beagle 2 mission’s hard landing in 2003.

But the probe’s goal is clear: to learn the early evolution of terrestrial planets such as Earth by tapping a Martian geological record more than 4 billion years old.

“Mars is not an easy place to land on, but we’ve done it a number of times,” said Bruce Banerdt, a planetary scientist at the Jet Propulsion Laboratory in Pasadena, Calif. “We’re going to try and do it exactly like how we did it with Phoenix a few years ago.”

The mission planners’ willingness to cannibalize technologies from other missions has allowed them to put together the Mars mission for relatively low cost. About 77 percent of the spacecraft is lifted from the Phoenix Mars Lander, and another 20 percent has just minor modifications. Only 3 percent of the spacecraft would need to be built from scratch or completely replaced.

Not specific enough for you? Here’s the abstract (PDF) by Bruce Banerdt and Zainab Nagin Cox…

The GEophysical Monitoring Station (GEMS) is a Phase A Discovery mission designed to fill a longstanding gap in the scientific exploration of the solar system by performing, for the first time, an in-situ investigation of the interior of Mars. This mission would provide unique and critical information about the fundamental processes governing the initial accretion of the planet, the formation and differentiation of its core and crust, and the subsequent evolution of the interior.

The scientific goals of GEMS are to understand the formation and evolution of terrestrial planets through investigation of the interior structure and processes of Mars and to determine its present level of tectonic activity and impact flux. A straightforward set of scientific objectives address these goals: 1) Determine the size, composition and physical state of the core; 2) Determine the thickness and structure of the crust; 3) Determine the composition and structure of the mantle; 4) Determine the thermal state of the interior; 5) Measure the rate and distribution of internal seismic activity; and 6) Measure the rate of impacts on the surface.

To accomplish these objectives, GEMS would carry a tightly-focused payload consisting of 3 investigations: 1) SEIS, a 6-component, very-broad-band seismometer, with careful thermal compensation/control and a sensitivity comparable to the best terrestrial instruments across a frequency range of 1 mHz to 50 Hz; 2) HP3 (Heat Flow and Physical Properties Package), an instrumented self-penetrating mole system that trails a string of temperature sensors to measure the planetary heat flux; and 3) RISE (Rotation and Interior Structure Experiment), which would use the spacecraft X-band communication system to provide precision tracking for planetary dynamical studies. The two instruments would be moved from the lander deck to the martian surface by an Instrument Deployment Arm, with an appropriate location identified using an Instrument Deployment Camera.

In order to ensure low risk within the tight Discovery cost limits, GEMS reuses the successful Lockheed Martin Phoenix spacecraft design, with a cruise and EDL system that has demonstrated capability for safe landing on Mars with well-understood costs. To take full advantage of this approach, all science requirements (such as instrument mass and power, landing site, and downlinked data volume) strictly conform to existing, demonstrated capabilities of the spacecraft and mission system.

It is widely believed that multiple landers making simultaneous measurements (a network) are required to address the objectives for understanding terrestrial planet interiors. Nonetheless, comprehensive measurements from a single geophysical station are extremely valuable, because observations constraining the structure and processes of the deep interior of Mars are virtually nonexistent. GEMS will utilize sophisticated analysis techniques specific to single-station measurements to determine crustal thickness, mantle structure, core state and size, and heat flow, providing our first real look deep beneath the surface of Mars.