Archive for June, 2013

From Landing to Sophomore Year and Back Again

Thursday, June 13th, 2013

By Clara Ma

Clara Ma and Family standing besides a model of the Mars Curiosity rover

Dear Fellow Martians,

While the Curiosity rover is busy exploring the Martian surface, I am going to school as a sophomore at Shawnee Mission East High School in Prairie Village, Kan. I am very involved in my school’s environmental club, and this year we started a composting program in our cafeteria.

I’ve also taken on a role in my local Sierra Club chapter’s energy efficiency campaign. I think caring for our planet goes hand-in-hand with science and exploration. It is something that is very important to me.

In February, I rode a bus to Washington, D.C., with 40 other people to attend the Forward On Climate Change rally. The bus ride was a little over 24 hours, but it didn’t feel that long at all. I had so much fun meeting and talking with people who had similar passions and motivations to those that I have. The rally and its immense energy opened my eyes to the things I could accomplish in my own community.

In May, I visited my grandparents in Beijing, China. Saying goodbye is always hard, because I absolutely love seeing them, talking to them, and being with them.

This week, I started my internship at JPL, one of my favorite places in the entire world. I am sure this will be the first of many letters that I will write to you. I can’t wait to tell you more about my experiences in Pasadena as my summer continues.

With love,
Clara

My Timeline:

Aug. 5, 2012: Curiosity lands in Gale Crater. I watch from Earth, crying and shouting on the edge of my seat.

Sept. 27, 2012: Curiosity finds evidence of an ancient streambed. I play my third tennis match of the season, and share the rover’s exciting discovery with my parents when I get home from school.

March 12, 2013: A rock sample analysis shows ancient Mars could have supported microbial life. I write about it in my chemistry assignment.

June 10, 2013: This is the first day of my internship at JPL, a day I have been dreaming about since I was a little girl. I don’t know how I got to be so lucky.


Smooth Sailing: Dawn Spacecraft Passes Endurance Test

Monday, June 3rd, 2013

By Marc Rayman
As NASA’s Dawn spacecraft makes its journey to its second target, the dwarf planet Ceres, Marc Rayman, Dawn’s chief engineer, shares a monthly update on the mission’s progress.

Mosaic of Dawn's images of asteroid Vesta
Artist’s concept of NASA’s Dawn spacecraft. Image credit: NASA/JPL-Caltech

Dear Confidawnts,

Traveling from one alien world to another, Dawn is reliably powering its way through the main asteroid belt with its ion propulsion system. Vesta, the fascinating and complex protoplanet it explored in 2011 and 2012, falls farther and farther behind as the spacecraft gently and patiently reshapes its orbit around the sun, aiming for a 2015 rendezvous with dwarf planet Ceres.

The stalwart adventurer has recently completed its longest uninterrupted ion thrust period yet. As part of the campaign to conserve precious hydrazine propellant, Dawn now suspends thrusting once every four weeks to point its main antenna to Earth. (In contrast, spacecraft with conventional chemical propulsion spend the vast majority of time coasting.) Because of details of the mission operations schedule and the schedule for NASA’s Deep Space Network, the thrust durations can vary by a few days. As a result, the spacecraft spent 31.2 days thrusting without a hiatus. This exceeds Deep Space 1’s longest sustained powered flight of 29.2 days. While there currently are no plans to thrust for longer times, the unique craft certainly is capable of doing so. The principal limitation is how much data it can store on the performance of all subsystems (pressures, temperatures, currents, voltages, valve positions, etc.) for subsequent reporting to its terrestrial colleagues.

Thanks to the ship’s dependability, the operations team has been able to devote much of its energies recently to developing and refining the complex plans for the exploration of Ceres. You might be among the privileged readers who will get a preview when we begin describing the plans later this year.

Controllers also have devised some special activities for the spacecraft to perform in the near future, accounts of which are predicted to be in the next two logs.

In addition, team members have had time to maintain their skills for when the spacecraft needs more attention. Earlier this month, they conducted an operational readiness test (ORT). One diabolical engineer carefully configured the Dawn spacecraft simulator at JPL to behave as if a pebble one-half of a centimeter (one-fifth of an inch) in diameter shooting through the asteroid belt collided with the probe at well over twice the velocity of a high-performance rifle bullet.

When the explorer entered this region of space, we discussed that it was not as risky as residents of other parts of the solar system might assume. Dawn does not require Han Solo’s piloting skills to avoid most of the dangerous rocky debris.

The robot could tolerate such a wound, but it would require some help from operators to resume normal operations. This exercise presented the spacecraft team with an opportunity to spend several days working through the diagnosis and performing the steps necessary to continue the mission (using some of the ship’s backup systems). While the specific problem is extremely unlikely to occur, the ORT provided valuable training for new members of the project and served to keep others sharp.

One more benefit of the smooth operations is the time that it enables your correspondent to write his third shortest log ever. (Feel free to do the implied research.) Frequent readers can only hope he strives to achieve such a gratifying feat again!

Dawn is 13 million kilometers (7.9 million miles) from Vesta and 54 million kilometers (34 million miles) from Ceres. It is also 3.25 AU (486 million kilometers or 302 million miles) from Earth, or 1,275 times as far as the moon and 3.20 times as far as the sun today. Radio signals, traveling at the universal limit of the speed of light, take 54 minutes to make the round trip.

› Read previous Dawn Journals by Marc Rayman